Recombinant subunit vaccines are biological preparations that are composed of microbial subunits produced using

recombinant DNA technology Molecular cloning is a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms. The use of the word ''cloning'' refers to the fact that the metho ...

. They act to provide active

acquired immunity The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system ...

infectious diseases An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

. The first recombinant subunit vaccine was produced in the mid-1980s to protect people from

Hepatitis B Hepatitis B is an infectious disease caused by the ''Hepatitis B virus'' (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection. Many people have no symptoms during an initial infection. Fo ...

. Notable recombinant subunit vaccines licensed include ENGERIX-B (

hepatitis B Hepatitis B is an infectious disease caused by the ''Hepatitis B virus'' (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection. Many people have no symptoms during an initial infection. Fo ...

), GARDASIL-9 (

Human Papillomavirus Human papillomavirus infection (HPV infection) is caused by a DNA virus from the ''Papillomaviridae'' family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and res ...

), FLUBLOK(

influenza Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms ...

SHINGRIX A zoster vaccine is a vaccine that reduces the incidence of herpes zoster (shingles), a disease caused by reactivation of the varicella zoster virus, which is also responsible for chickenpox. Shingles provokes a painful rash with blisters, and ...

(

Herpes Zoster Shingles, also known as zoster or herpes zoster, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. ...

) and NUVAXOVID (

Coronavirus Disease 2019 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quickly ...

). After

injection Injection or injected may refer to: Science and technology * Injective function, a mathematical function mapping distinct arguments to distinct values * Injection (medicine), insertion of liquid into the body with a syringe * Injection, in broadca ...

, antigens trigger the production of antigen-specific

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

, which are responsible for recognising and neutralising foreign substances. Basic components of recombinant subunit vaccines include recombinant subunits,

adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Analgesi ...

and carriers. Additionally, recombinant subunit vaccines are popular candidates for the development of

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...

s against

(e.g.

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...

dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

) Recombinant subunit vaccines are considered to be safe for injection. The chances of

adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complica ...

s vary depending on the specific type of

being administered. Minor side effects include injection site pain, fever, and

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

, and serious

s consist of

anaphylaxis Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follow ...

and potentially fatal

allergic reaction Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...

. The

contraindication In medicine, a contraindication is a condition that serves as a reason not to take a certain medical treatment due to the harm that it would cause the patient. Contraindication is the opposite of indication, which is a reason to use a certain tre ...

s are also vaccine-specific; they are generally not recommended for people with the previous history of

to any component of the vaccines. Advice from medical professionals should be sought before receiving any vaccination. __TOC__

History

While the practice of

immunisation Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an infectious agent (known as the immunogen). When this system is exposed to molecules that are foreign to the body, called ''non-sel ...

can be traced back to the 12th century, in which ancient

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

at that time employed the technique of

variolation Variolation was the method of inoculation first used to immunize individuals against smallpox (''Variola'') with material taken from a patient or a recently variolated individual, in the hope that a mild, but protective, infection would result. Var ...

to confer

immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity desc ...

smallpox Smallpox was an infectious disease caused by variola virus (often called smallpox virus) which belongs to the genus Orthopoxvirus. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization (WHO) c ...

infection, the modern era of vaccination has a short history of around 200 years. It began with the

invention An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an i ...

of a vaccine by Edward Jenner in 1798 to eradicate

by injecting relatively weaker

cowpox Cowpox is an infectious disease caused by the ''cowpox virus'' (CPXV). It presents with large blisters in the skin, a fever and swollen glands, historically typically following contact with an infected cow, though in the last several decades more ...

virus into the human body. The middle of the 20th century marked the golden age of vaccine science. Rapid technological advancements during this period of time enabled scientists to cultivate

cell culture Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist Montrose Thomas Burrows. This te ...

under controlled environments in laboratories, subsequently giving rise to the production of vaccines against

polio Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 70% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe s ...

myelitis,

measles Measles is a highly contagious infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than , cough, ...

and various

communicable diseases An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

. Conjugated vaccines were also developed using

immunologic Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there ...

markers including capsular

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s. Creation of products targeting common illnesses successfully lowered infection-related

mortality Mortality is the state of being mortal, or susceptible to death; the opposite of immortality. Mortality may also refer to: * Fish mortality, a parameter used in fisheries population dynamics to account for the loss of fish in a fish stock throug ...

and reduced

public healthcare Publicly funded healthcare is a form of health care financing designed to meet the cost of all or most healthcare needs from a publicly managed fund. Usually this is under some form of democratic accountability, the right of access to which are ...

burden. Emergence of

genetic engineering techniques Genetic engineering techniques allow the modification of animal and plant genomes. Techniques have been devised to insert, delete, and modify DNA at multiple levels, ranging from a specific base pair in a specific gene to entire genes. There are ...

revolutionised the creation of vaccines. By the end of the 20th century, researchers had the ability to create

recombinant vaccines A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified.

apart from traditional whole cell vaccines, for instance

Hepatitis B vaccine Hepatitis B vaccine is a vaccine that prevents hepatitis B. The first dose is recommended within 24 hours of birth with either two or three more doses given after that. This includes those with poor immune function such as from HIV/AIDS and th ...

, which uses the viral

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

s to initiate

immune response An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including viruses, bacteria, parasites, and fungi which could ...

s. As the

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...

methods continue to evolve, vaccines with more complex constitutions will inevitably be generated in the future to extend their therapeutic applications to both infectious and

non-infectious diseases A non-communicable disease (NCD) is a disease that is not transmissible directly from one person to another. NCDs include Parkinson's disease, autoimmune diseases, strokes, most heart diseases, most cancers, diabetes, chronic kidney disease, oste ...

, in order to safeguard the health of more people.

Features

When compared with conventional

attenuated vaccine An attenuated vaccine (or a live attenuated vaccine, LAV) is a vaccine created by reducing the virulence of a pathogen, but still keeping it viable (or "live"). Attenuation takes an infectious agent and alters it so that it becomes harmless or less ...

s and

inactivated vaccine An inactivated vaccine (or killed vaccine) is a vaccine consisting of virus particles, bacteria, or other pathogens that have been grown in culture and then killed to destroy disease-producing capacity. In contrast, live vaccines use pathogens t ...

s, recombinant subunit vaccines have the following special characteristics: * They contain clearly identified compositions which greatly reduces the possibility of presence of undesired materials within the

. * Their pathogenicities are minimized as only fragments of the pathogen are present in the

which cannot invade and multiply within the human body. * They have better safety profiles and are suitable to be administered to

immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

patients. * They are suitable for

mass production Mass production, also known as flow production or continuous production, is the production of substantial amounts of standardized products in a constant flow, including and especially on assembly lines. Together with job production and batch ...

due to the use of recombinant technologies. * They have high stability so they can withstand environmental changes and are more convenient to be used in community settings. However, there are also some drawbacks regarding recombinant subunit vaccines: * Addition of

is necessary during

to increase the

efficacy Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a pragmatic clinical trial#Efficacy versu ...

of these vaccines * Patients will have to receive

booster dose A booster dose is an extra administration of a vaccine after an earlier (primer) dose. After initial immunization, a booster provides a re-exposure to the immunizing antigen. It is intended to increase immunity against that antigen back to protec ...

s to maintain long-term

* Selection of appropriate cell lines for the cultivation of subunits is time-consuming because microbial proteins can be incompatible to certain expression systems

Pharmacology

Vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...

is a potent way to protect individuals against

Active immunity The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system ...

can be acquired artificially by

vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...

as a result of the body's own defense mechanism being triggered by the exposure of a small, controlled amount of

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

ic substances to produce its own antibodies and memory cells without being infected by the real pathogen. The processes involved in primary immune response are as follows: # Pre-exposure to the

s present in

s elicits a primary response. After injection, antigens will be

ingested Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms inges ...

by antigen-presenting cells (APCs), such as

dendritic cell Dendritic cells (DCs) are antigen-presenting cells (also known as ''accessory cells'') of the mammalian immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. ...

s and

macrophage Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer cel ...

s, via

phagocytosis Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is ...

. # The APCs will travel to

lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that inclu ...

s, where immature

B cell B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or ...

s and

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

s are present. # Following antigen processes by APCs, antigens will bind to either MHC class I receptors or MHC class II receptors on the cell surface of the cells based on their compositional and structural features to form complexes. #

Antigen presentation Antigen presentation is a vital immune process that is essential for T cell immune response triggering. Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment, now ...

occurs, in which T cell receptors attach to the antigen-MHC complexes, initiating clonal expansion and differentiation, and hence the conversion of

naive T cell In immunology, a naive T cell (Th0 cell) is a T cell that has differentiated in the thymus, and successfully undergone the positive and negative processes of central selection in the thymus. Among these are the naive forms of helper T cells ( CD ...

s to cytotoxic T cells (CD8+) or helper T cells (CD4+). # Cytotoxic CD8+ cells can directly destroy the infected cells containing the

s that were presented to them by the APCs by releasing lytic molecules, while helper CD4+ cells are responsible for the secretion of

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

s that activates

s and

cytotoxic T cell A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular pa ...

s. #

s can undergo activation in the absence of

s via the

receptor signalling pathway. # After

s capture the

immunogen An immunogen is any substance that generates B-cell (humoral/antibody) and/or T-cell (cellular) adaptive immune responses upon exposure to a host organism. Immunogens that generate antibodies are called antigens ("antibody-generating"). Immunogen ...

present in the

, they can present the substances to

naive B cell A naive B cell is a B cell that has not been exposed to an antigen. These are located in the tonsils, spleen, primary lymphoid follicles in lymph nodes Once exposed to an antigen, the naive B cell either becomes a memory B cell In immunology, a ...

s, causing the proliferation of

plasma cell Plasma cells, also called plasma B cells or effector B cells, are white blood cells that originate in the lymphoid organs as B lymphocytes and secrete large quantities of proteins called antibodies in response to being presented specific substan ...

s for

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

production.

Isotype switching Immunoglobulin class switching, also known as isotype switching, isotypic commutation or class-switch recombination (CSR), is a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the ...

can take place during

development for the formation of different antibodies, including

IgG Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG ...

IgE Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig) " isotype") that has been found only in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε c ...

and

IgA Iga may refer to: Arts and entertainment * Ambush at Iga Pass, a 1958 Japanese film * Iga no Kagemaru, Japanese manga series * Iga, a set of characters from the Japanese novel '' The Kouga Ninja Scrolls'' Biology * ''Iga'' (beetle), a gen ...

. #

Memory B cell In immunology, a memory B cell (MBC) is a type of B lymphocyte that forms part of the adaptive immune system. These cells develop within germinal centers of the secondary lymphoid organs. Memory B cells circulate in the blood stream in a quiescen ...

s and

T cells A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell re ...

are formed post-infection. The

s are memorised by these cells so that subsequent exposure to the same type of antigens will stimulate a secondary response, in which a higher concentration of

specific for the

s are reproduced rapidly and efficiently in a short time for the elimination of the

. Under specific circumstances, low doses of

s are given initially, followed by additional doses named

s. Boosters can effectively maintain the level of memory cells in the human body, hence extending a person's

Manufacturing

The manufacturing process of recombinant subunit

s are as follows: # Identification of

immunogenic Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted: * Wanted immunogenicity typically relates to vaccines, where the injectio ...

subunit # Subunit

expression Expression may refer to: Linguistics * Expression (linguistics), a word, phrase, or sentence * Fixed expression, a form of words with a specific meaning * Idiom, a type of fixed expression * Metaphorical expression, a particular word, phrase, o ...

and synthesis # Extraction and purification # Addition of

adjuvant In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Analgesic ...

s or incorporation to vectors #

Formulation Formulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formul ...

and delivery.

Identification of immunogenic subunit

Candidate subunits will be selected primarily by their

immunogenicity Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted: * Wanted immunogenicity typically relates to vaccines, where the injectio ...

. To be

, they should be of foreign nature and of sufficient complexity for the reaction between different components of the

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

and the candidates to occur. Candidates are also selected based on size, nature of function (e.g.

signalling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

) and cellular location (e.g.

transmembrane A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequentl ...

Subunit expression and synthesis

Upon identifying the target subunit and its encoding

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

, the

will be isolated and transferred to a second, non-pathogenic organism, and cultured for

. The process is also known as

heterologous expression Heterologous expression refers to the expression of a gene or part of a gene in a host organism that does not naturally have the gene or gene fragment in question. Insertion of the gene in the heterologous host is performed by recombinant DNA techno ...

. A suitable

expression system Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

is selected based on the requirement of

post-translational modification Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosome ...

s, costs, ease of product extraction and production efficiency. Commonly used systems for both licensed and developing recombinant subunit

s include

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

ian cells,

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

cells.

Bacterial cells

Bacterial cells are widely used for cloning processes,

genetic modification Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...

and small-scale productions. Escherichia coli (E. Coli) is widely utilised due to its highly explored

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

, widely available genetic tools for

gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

, accurate profiling and its ability to grow in inexpensive

media Media may refer to: Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Broadcast media, communications delivered over mass el ...

at high cell densities. E. Coli is mostly appropriate for structurally simple proteins owing to its inability to carry out

post-translational modifications Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosomes ...

, lack of protein secretary system and the potential for producing

inclusion bodies Inclusion bodies are aggregates of specific types of protein found in neurons, a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells ...

that require additional solubilisation. Regarding application,

E.Coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Esche ...

is being utilised as the

of the currently developing

dengue vaccine Dengue vaccine is a vaccine used to prevent dengue fever in humans. Development of dengue vaccines began in the 1920s, but was hindered by the need to create immunity against all four dengue serotypes. As of 2022, there are two commercially ava ...

Yeast

Yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

matches bacterial cells' cost-effectiveness, efficiency and technical feasibility. Moreover,

secretes

soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...

s and has the ability to perform

s similar to

ian cells. Saccharomyces cerevisiae YGC colonies 50

Notably, yeast incorporates more

mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation ...

molecules during

N-glycosylation ''N''-linked glycosylation, is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom (the amide nitrogen of an asparagine (Asn) residue of a protein), ...

when compared with other

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s, which may trigger cellular conformational stress responses. Such responses may result in failure in reaching native protein conformation, implying potential reduction of serum half-life and

. Regarding application, both the hepatitis B virus surface antigen (

HBsAg HBsAg (also known as the Australia antigen) is the surface antigen of the hepatitis B virus (HBV). Its presence in blood indicates current hepatitis B infection. Structure and function The viral envelope of an enveloped virus has different sur ...

) and the

virus-like particle Virus-like particles (VLPs) are molecules that closely resemble viruses, but are non-infectious because they contain no viral genetic material. They can be naturally occurring or synthesized through the individual expression of viral structural pro ...

s (

VLPs Virus-like particles (VLPs) are molecules that closely resemble viruses, but are non-infectious because they contain no viral genetic material. They can be naturally occurring or synthesized through the individual expression of viral structural pro ...

) of the major capsid protein L1 of

human papillomavirus Human papillomavirus infection (HPV infection) is caused by a DNA virus from the ''Papillomaviridae'' family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and res ...

type 6, 11, 16, 18 are produced by ''

Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been o ...

.'' Currently, all commercialised therapeutic proteins to date are non-glycosylated.

Mammalian cells

Mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

ian cells are well known for their ability to perform therapeutically essential

s and express properly folded,

glycosylated Glycosylation is the reaction in which a carbohydrate (or 'glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not alw ...

and functionally active proteins. However, efficacy of mammalian cells may be limited by

epigenetic In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...

gene silencing Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is often used in research. In particular, methods used to silence gen ...

and

aggresome In eukaryotic cells, an aggresome refers to an aggregation of misfolded proteins in the cell, formed when the protein degradation system of the cell is overwhelmed. Aggresome formation is a highly regulated process that possibly serves to organize m ...

formation (recombinant protein aggregation). For mammalian cells, synthesised proteins were reported to be secreted into chemically defined media, potentially simplifying protein extraction and purification. The most prominent example under this class is Chinese Hamster Ovary (CHO) cells utilised for the synthesis of recombinant

varicella zoster virus Varicella-zoster virus (VZV), also known as human herpesvirus 3 (HHV-3, HHV3) or ''Human alphaherpesvirus 3'' (taxonomically), is one of nine known herpes viruses that can infect humans. It causes chickenpox (varicella) commonly affecting chil ...

surface glycoprotein (gE) antigen for

CHO cells Chinese hamster ovary (CHO) cells are an epithelial cell line derived from the ovary of the Chinese hamster, often used in biological and medical research and commercially in the production of recombinant therapeutic proteins. They have foun ...

are recognised for rapid growth and their ability to offer process versatility. They can also be cultured in suspension-adapted culture in protein-free medium, hence reducing risk of

prion Prions are misfolded proteins that have the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many other animals. It ...

-induced contamination.

Baculovirus (insect) cells

The

baculovirus ''Baculoviridae'' is a family of viruses. Arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropod ...

cell

has the ability to express a variety of

recombinant proteins Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) that bring together genetic material from multiple sources, creating sequences that would not otherwise be foun ...

at high levels and provide significant eukaryotic protein processing capabilities, including

phosphorylation In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...

glycosylation Glycosylation is the reaction in which a carbohydrate (or ' glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not al ...

myristoylation Myristoylation is a lipidation modification where a myristoyl group, derived from myristic acid, is covalently attached by an amide bond to the alpha-amino group of an N-terminus, N-terminal glycine residue. Myristic acid is a 14-carbon saturat ...

and

palmitoylation Palmitoylation is the covalent attachment of fatty acids, such as palmitic acid, to cysteine (''S''-palmitoylation) and less frequently to serine and threonine (''O''-palmitoylation) residues of proteins, which are typically lipid bilayer, memb ...

. Similar to

ian cells, proteins expressed are mostly

, accurately folded, and biologically active. However, it has slower growth rate and requires higher cost of

growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...

than

and

, and confers

toxicological Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating expos ...

risks. A notable feature is the existence of elements of control that allow for the expression of secreted and

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

-bound proteins in Baculovirus-insect cells. Licensed recombinant subunit

s that utilises

cells include

Cervarix Cervarix is a vaccine against certain types of cancer-causing human papillomavirus (HPV). Cervarix is designed to prevent infection from HPV types 16 and 18, that cause about 70% of cervical cancer cases. These types also cause most HPV-induced ...

(papillomavirus C-terminal truncated major capsid protein L1 types 16 and 18) and Flublok Quadrivalent (

hemagglutinin In molecular biology, hemagglutinins (or ''haemagglutinin'' in British English) (from the Greek , 'blood' + Latin , 'glue') are receptor-binding membrane fusion glycoproteins produced by viruses in the ''Paramyxoviridae'' family. Hemagglutinins ar ...

( HA) proteins from four strains of

influenza viruses ''Orthomyxoviridae'' (from Greek language, Greek ὀρθός, ''orthós'' 'straight' + μύξα, ''mýxa'' 'mucus') is a family of negative-sense single-stranded RNA virus, negative-sense RNA viruses. It includes seven genus, genera: ''Influenza ...

Extraction and purification

Throughout history, extraction and purification methods have evolved from standard chromatographic methods to the utilisation of affinity tags. However, the final extraction and purification process undertaken highly depends on the chosen

. Please refer to subunit expression and synthesis for more insights.

Addition of adjuvants

Adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Analgesi ...

are materials added to improve

of recombinant subunit

increase the magnitude of

adaptive response The adaptive response is a form of direct DNA repair in '' E. coli'' that protects DNA from damage by external agents or by errors during replication.Landini, P, Volkert MR. (2000Regulatory Responses of the Adaptive Response to Alkylation Damage: a ...

to the

and guide the activation of the most effective forms of

for each specific

(e.g. increasing generation of T cell memory). Addition of

may confer benefits including dose sparing and stabilisation of final vaccine formulation. Appropriate

are chosen based on safety, tolerance, compatibility of antigen and

considerations. Commonly used

for recombinant subunit

s are

Alum An alum () is a type of chemical compound, usually a hydrated double salt, double sulfate salt (chemistry), salt of aluminium with the general chemical formula, formula , where is a valence (chemistry), monovalent cation such as potassium or a ...

(e.g.

aluminium hydroxide Aluminium hydroxide, Al(OH)3, is found in nature as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric, i.e., it has both basic and ...

Emulsion An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althoug ...

s (e.g.

MF59 MF59 is an immunologic adjuvant that uses squalene. It is Novartis' proprietary adjuvant that is added to influenza vaccines to help stimulate the human body's immune response through production of CD4 memory cells. MF59 is the first oil-in-water ...

) and

Liposome A liposome is a small artificial vesicle, spherical in shape, having at least one lipid bilayer. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as drug deliver ...

s combined with

immunostimulatory Immunostimulants, also known as immunostimulators, are substances (drugs and nutrients) that stimulate the immune system by inducing activation or increasing activity of any of its components. One notable example is the granulocyte macrophage colon ...

molecules (e.g. AS01_B).

Formulation and delivery

Delivery systems are primarily divided into polymer-based delivery systems (

microspheres Microparticles are particles between 0.1 and 100 μm in size. Commercially available microparticles are available in a wide variety of materials, including ceramics, glass, polymers, and metals. Microparticles encountered in daily life includ ...

and

liposome A liposome is a small artificial vesicle, spherical in shape, having at least one lipid bilayer. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as drug deliver ...

s) and live delivery systems (

gram-positive bacteria In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

and

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

es)

Polymer-based delivery systems

Vaccine antigens are often encapsulated within

s. Common microspheres made using Poly-lactic acid (PLA) and poly-lactic-co-glycolic acid (PLGA) allow for controlled

release by degrading in vivo while

s including multilamellar or unilamellar vesicles allow for prolonged release. Polymer-based delivery systems confer advantages such as increased resistance to degradation in

GI tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

, controlled

release, raised particle uptake by

immune cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

and enhanced ability to induce

responses. An example of licensed recombinant vaccine utilising

liposomal A liposome is a small artificial vesicle, spherical in shape, having at least one lipid bilayer. Due to their hydrophobicity and/or hydrophilicity, biocompatibility, particle size and many other properties, liposomes can be used as drug deliver ...

delivery is Shringrix.

Live delivery systems

Live delivery systems, also known as vectors, are cells modified with

ligands In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...

s to improve the

of recombinant subunits via altering

antigen presentation Antigen presentation is a vital immune process that is essential for T cell immune response triggering. Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment, now ...

biodistribution Biodistribution is a method of tracking where compounds of interest travel in an experimental animal or human subject. For example, in the development of new compounds for PET (positron emission tomography) scanning, a radioactive isotope is chemic ...

and trafficking. Subunits may either be inserted within the carrier or

genetically engineered Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...

to be expressed on the surface of the vectors for efficient presentation to the mucosal immune system.

Adverse effects and contraindications

Recombinant subunit

s are safe for administration. However, mild local reactions, including

induration A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sy ...

and swelling of the injection site, along with

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

and

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

may be encountered after vaccination. Occurrence of severe

hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune s ...

reactions and

is rare, but can possibly lead to

death Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...

s of individuals.

Adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complica ...

s can vary among populations depending on their

physical health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...

condition, age,

gender Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most cultures u ...

and genetic predisposition. Recombinant subunit

s are

contraindicated In medicine, a contraindication is a condition that serves as a reason not to take a certain medical treatment due to the harm that it would cause the patient. Contraindication is the opposite of indication, which is a reason to use a certain tre ...

to people who have experienced

allergic reactions Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...

and

s or other components of the

s previously. Furthermore, precautions should be taken when administering

s to people who are in

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

d state and during

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

, in which their injections should be delayed until their conditions become stable and after childbirth respectively.

Licensed vaccines

Hepatitis B

ENGERIX-B (produced by GSK) and RECOMBIVAX HB (produced by merck) are two recombinant subunit

s licensed for the protection against

. Both contain

harvested and purified from ''

'' and are formulated as a suspension of the

adjuvanted with

alum An alum () is a type of chemical compound, usually a hydrated double salt, double sulfate salt (chemistry), salt of aluminium with the general chemical formula, formula , where is a valence (chemistry), monovalent cation such as potassium or a ...

Antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

concentration ≥10mIU/mL against

are recognized as conferring protection against hepatitis B infection. It has been shown that primary 3-dose

of healthy individuals is associated with ≥90% seroprotection rates for ENGERIX-B, despite decreasing with older age. Lower seroprotection rates are also associated with presence of underlying

chronic diseases A chronic condition is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term ''chronic'' is often applied when the course of the disease lasts for more than three mo ...

and

immunodeficiency Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

. Yet, GSK HepB still has a clinically acceptable safety profile in all studied populations.

Human Papillomavirus (HPV)

GARDASIL Gardasil is an HPV vaccine for use in the prevention of certain strains of human papillomavirus (HPV). Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledge ...

and GARDASIL9 are three recombinant subunit

s licensed for the protection against

HPV Human papillomavirus infection (HPV infection) is caused by a DNA virus from the '' Papillomaviridae'' family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and re ...

infection. They differ in the strains which they protect the patients from as

confers protection against type 16 and 18,

confers protection against type 6, 11, 16 and 18, and GARDASIL9 confers protection against type 6, 11, 16, 18, 31, 33, 45, 52, 58 respectively. The

s contain purified VLP of the major capsid L1 protein produced by recombinant ''

''. It has been shown in a 2014 systematic quantitative review that the bivalent HPV vaccine (

) is associated with

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

(OR 3.29; 95% CI: 3.00–3.60), swelling (OR 3.14; 95% CI: 2.79–3.53) and redness (OR 2.41; 95% CI: 2.17–2.68) being the most frequently reported adverse effects. For

, the most frequently reported events were

(OR 2.88; 95% CI: 2.42–3.43) and swelling (OR 2.65; 95% CI: 2.0–3.44).

was discontinued in the U.S. on May 8, 2017, after the introduction of GARDASIL9 and

was also voluntarily withdrawn in the U.S. on August 8, 2016.

Influenza

Flublok Quadrivalent is a licensed recombinant subunit

for active

against

. It contains HA proteins of four strains of

virus purified and extracted using the

Baculovirus ''Baculoviridae'' is a family of viruses. Arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropod ...

. The four viral strains are standardised annually according to United States Public Health Services (USPHS) requirements. Flublok Quadrivalent has a comparable safety profile to traditional trivalent and quadrivalent vaccine equivalents. Flublok is also associated with less local reactions (RR = 0.94, 95% CI 0.90–0.98, three RCTs, FEM, I2 = 0%, low‐ certainty evidence) and higher risk of

chills Chills is a feeling of coldness occurring during a high fever, but sometimes is also a common symptom which occurs alone in specific people. It occurs during fever due to the release of cytokines and prostaglandins as part of the inflammatory r ...

(RR = 1.33, 95% CI 1.03–1.72, three RCTs, FEM, I2 = 14%, low‐certainty evidence).

Herpes Zoster

is a licensed recombinant subunit

for protection against

, whose risk of developing increases with decline of varicella zoster virus (VZV) specific

. The vaccine contains VZV gE antigen component extracted from

, which is to be reconstituted with

suspension AS01_B.

Systematic review A systematic review is a Literature review, scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from publ ...

s and

meta-analyses A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

have been conducted on the efficacy, effectiveness and safety of

18-49 year old patients and healthy adults aged 50 and over. These studies reported

humoral Humoral immunity is the aspect of immunity that is mediated by macromolecules - including secreted antibodies, complement proteins, and certain antimicrobial peptides - located in extracellular fluids. Humoral immunity is named so because it invo ...

and

cell-mediated immunity Cell-mediated immunity or cellular immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in ...

rate ranged between 65.4 and 96.2% and 50.0%-93.0% while efficacy in patients (18-49 yo) with haematological malignancies was estimated at 87.2% (95%CI, 44.3–98.6%) up to 13 months post-vaccination with an acceptable safety profile.

COVID-19

NUVAXOVID is a recombinant subunit vaccine licensed for the prevention of SARS-CoV-2 infection. Market authorization was issued on 20 December 2021. The vaccine contains the SARS-CoV-2 spike protein produced using the

, which is eventually adjuvanted with the Matrix M adjuvant.

Research

Currently, recombinant subunit

s are used in development for

Tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...

Dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

Soil-transmitted Helminths The soil-transmitted helminths (also called geohelminths) are a group of intestinal parasites belonging to the phylum Nematoda that are transmitted primarily through contaminated soil. They are so called because they have a direct life cycle whic ...

Feline Leukaemia Feline leukemia virus (FeLV) is a retrovirus that infects cats. FeLV can be transmitted from infected cats when the transfer of saliva or nasal secretions is involved. If not defeated by the animal's immune system, the virus weakens the cat's im ...

and

COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was COVID-19 pandemic in Hubei, identified in Wuhan, China, in December ...

COVID-19

Research has been conducted to explore the possibility of developing a heterologous

SARS-CoV Severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1; or Severe acute respiratory syndrome coronavirus, SARS-CoV) is a strain of coronavirus that causes severe acute respiratory syndrome (SARS), the respiratory illness responsible for t ...

receptor-binding domain (RBD) recombinant protein as a human

against

. The theory is supported by evidence that

convalescent Convalescence is the gradual recovery of health and strength after illness or injury. It refers to the later stage of an infectious disease or illness when the patient recovers and returns to previous health, but may continue to be a source of ...

serum from

patients have the ability to neutralise

SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19 (coronavirus disease 2019), the respiratory illness responsible for the ongoing COVID-19 pandemic. The virus previously had a ...

(corresponding virus for

) and that amino acid similarity between

and SARS-CoV-2 spike and RBD protein is high (82%). :Subunit vaccines

References

{{improve categories, date=June 2022 Vaccines Pharmacology Subunit vaccines