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A single-domain antibody (sdAb), also known as a nanobody, is an
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 ...
fragment consisting of a single
monomer
In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.
Classification
Mo ...
ic
variable antibody domain. Like a whole antibody, it is able to bind selectively to a specific
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. ...
. With a molecular weight of only 12–15
kDa
The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at ...
, single-domain antibodies are much smaller than common antibodies (150–160 kDa) which are composed of two
heavy protein chains and two
light chains, and even smaller than
Fab fragment
The fragment antigen-binding region (Fab region) is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain. The variable domain contains the paratope (the ant ...
s (~50 kDa, one light chain and half a heavy chain) and
single-chain variable fragment
A single-chain variable fragment (scFv) is not actually a fragment of an antibody, but instead is a fusion protein of the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins, connected with a short linker peptide of ten ...
s (~25 kDa, two variable domains, one from a light and one from a heavy chain).
The first single-domain antibodies were engineered from
heavy-chain antibodies
A heavy-chain antibody is an antibody which consists only of two heavy chains and lacks the two light chains usually found in antibodies.
In common antibodies, the antigen binding region consists of the variable domains of the heavy and light c ...
found in
camelid
Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, ...
s; these are called V
HH fragments.
Cartilaginous fishes
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue ...
also have heavy-chain antibodies (IgNAR, 'immunoglobulin new antigen receptor'), from which single-domain antibodies called V
NAR fragments can be obtained. An alternative approach is to split the dimeric variable domains from common
immunoglobulin G
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 a ...
(IgG) from humans or mice into monomers. Although most research into single-domain antibodies is currently based on heavy chain variable domains, nanobodies derived from light chains have also been shown to bind specifically to target
epitopes
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...
.
Camelid nanobodies have been shown to be just as specific as antibodies, and in some cases they are more robust. They are easily isolated using the same phage panning procedure used for antibodies, allowing them to be cultured in vitro in large concentrations. The smaller size and single domain make these antibodies easier to transform into bacterial cells for bulk production, making them ideal for research purposes.
Single-domain antibodies are being researched for multiple pharmaceutical applications, and have potential for use in the treatment of
acute coronary syndrome
Acute coronary syndrome (ACS) is a syndrome (a set of signs and symptoms) due to decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies. The most common symptom is centrally loca ...
,
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
,
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
, 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 ...
.
Properties
A single-domain antibody is a
peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
A ...
chain of about 110
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
s long, comprising one variable domain (V
H) of a heavy-chain antibody, or of a common IgG. These peptides have similar affinity to antigens as whole antibodies, but are more heat-resistant and stable towards
detergent
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...
s and high concentrations of
urea
Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid.
Urea serves an important r ...
. Those derived from camelid and fish antibodies are less
lipophilic
Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipop ...
and more
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 ...
in water, owing to their
complementarity-determining region 3
Complementarity-determining regions (CDRs) are part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen. A set of CDRs c ...
(CDR3), which forms an extended loop (coloured orange in the ribbon diagram above) covering the lipophilic site that normally binds to a light chain.
In contrast to common antibodies, two out of six single-domain antibodies survived a temperature of 90 °C (194 °F) without losing their ability to bind antigens in a 1999 study. Stability towards
gastric acid
Gastric acid, gastric juice, or stomach acid is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the ...
and
proteases
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the for ...
depends on the amino acid sequence. Some species have been shown to be active in the
intestine
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 ...
after oral application,
but their low
absorption
Absorption may refer to:
Chemistry and biology
* Absorption (biology), digestion
**Absorption (small intestine)
*Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials
*Absorption (skin), a route by which ...
from the gut impedes the development of systemically active orally administered single-domain antibodies.
The comparatively low
molecular mass
The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...
leads to a better permeability in tissues, and to a short plasma
half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
since they are eliminated
renal
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
ly.
Unlike whole antibodies, they do not show
complement system
The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and at ...
triggered
cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
because they lack an
Fc region
The fragment crystallizable region (Fc region) is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune s ...
. Camelid and fish derived sdAbs are able to bind to hidden antigens that are not accessible to whole antibodies, for example to the active sites of
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s.
This property has been shown to result from their extended CDR3 loop, which is able to penetrate such buried sites.
Production
From heavy-chain antibodies
A single-domain antibody can be obtained by immunization of
dromedaries
The dromedary (''Camelus dromedarius'' or ;), also known as the dromedary camel, Arabian camel, or one-humped camel, is a large even-toed ungulate, of the genus ''Camelus'', with one hump on its back.
It is the tallest of the three species of ...
,
camel
A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. C ...
s,
llama
The llama (; ) (''Lama glama'') is a domesticated South American camelid, widely used as a List of meat animals, meat and pack animal by Inca empire, Andean cultures since the Pre-Columbian era.
Llamas are social animals and live with othe ...
s,
alpaca
The alpaca (''Lama pacos'') is a species of South American camelid mammal. It is similar to, and often confused with, the llama. However, alpacas are often noticeably smaller than llamas. The two animals are closely related and can successfu ...
s or
shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
s with the desired antigen and subsequent isolation of the
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein.
mRNA is ...
coding for heavy-chain antibodies. Large phage displayed V
NAR and V
HH single domain libraries were established from nurse sharks
and dromedary camels.
Screening techniques like
phage display
Phage display is a laboratory technique for the study of protein–protein, protein–peptide, and protein– DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes ...
and
ribosome display Ribosome display is a technique used to perform ''in vitro'' protein evolution to create proteins that can bind to a desired ligand. The process results in translated proteins that are associated with their mRNA progenitor which is used, as a compl ...
help to identify the clones binding the antigen.
From conventional antibodies
Alternatively, single-domain antibodies can be made from common
murine
The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families excep ...
, rabbit
or human IgG with four chains. The process is similar, comprising gene libraries from immunized or naïve donors and display techniques for identification of the most specific antigens. A problem with this approach is that the binding region of common IgG consists of two domains (V
H and V
L), which tend to
dimerize
A dimer () ('' di-'', "two" + ''-mer'', "parts") is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. Dimers also have significant implications in polymer chemistry, inorganic ch ...
or aggregate because of their lipophilicity. Monomerization is usually accomplished by replacing lipophilic by hydrophilic amino acids, but often results in a loss of affinity to the antigen. If affinity can be retained, the single-domain antibodies can likewise be produced in ''E. coli'',
''S. cerevisiae'' or other organisms.
From human single-domain antibodies
Humans occasionally produce single domain antibodies by the random creation of a stop codon in the light chain. Human single-domain antibodies targeting various tumor antigens including mesothelin, GPC2
and GPC3
were isolated by phage display. The human single-domain antibodies have been used to create immunotoxins (HN3-PE38, HN3-mPE24, HN3-T20)
and chimeric antigen receptor (CAR) T cells
for treating cancer. Blocking the Wnt binding domain on the protein core of GPC3 by the HN3 human single-domain antibody inhibits Wnt activation in liver cancer cells.
Potential applications
Single-domain antibodies allow a broad range of applications in biotechnical as well as therapeutic use due to their small size, simple production and high affinity.
Biotechnological and diagnostic
The fusion of a fluorescent protein to a nanobody generates a so-called
chromobody. Chromobodies can be used to recognize and trace targets in different compartments of living cells. They can therefore increase the possibilities of live cell microscopy and will enable novel functional studies. The coupling of an anti-
GFP GFP may refer to:
Organisations
* Gaelic Football Provence, a French Gaelic Athletic Association club
* Geheime Feldpolizei, the German secret military police during the Second World War
* French Group for the Study of Polymers and their Applicat ...
Nanobody to a monovalent matrix, called GFP-nanotrap, allows the isolation of GFP-fusion proteins and their interacting partners for further biochemical analyses. Single molecule localization with super-resolution imaging techniques requires the specific delivery of
fluorophore
A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with se ...
s into close proximity with a target protein. Due to their large size the use of antibodies coupled to organic dyes can often lead to a misleading signal owing to the distance between the fluorophore and the target protein. The fusion of organic dyes to anti-GFP Nanobodies targeting GFP-tagged proteins allows nanometer spatial resolution and minimal linkage error because of the small size and high affinity. The size dividend of nanobodies also benefits the
correlative light-electron microscopy Correlative light-electron microscopy (CLEM) is the combination of an optical microscope - usually a fluorescence microscope - with an electron microscope. In an integrated CLEM system, the sample is imaged using an electron beam and an optical ligh ...
study. Without any permeabilization agent, the cytoplasm of the chemically fixed cells are readily accessible to the fluorophore tagged nanobodies. Their small size also allows them to penetrate deeper into volumetric samples than regular antibodies. High ultrastructural quality is preserved in the tissue that is imaged by fluorescence microscope and then electron microscope. This is especially useful for the neuroscience research that requires both molecular labeling and electron microscopic imaging.
In diagnostic
biosensor
A biosensor is an analytical device, used for the detection of a chemical substance, that combines a biological component with a physicochemical detector.
The ''sensitive biological element'', e.g. tissue, microorganisms, organelles, cell recep ...
applications nanobodies may be used prospectively as a tool. Due to their small size, they can be coupled more densely on biosensor surfaces. In addition to their advantage in targeting less accessible epitopes, their conformational stability also leads to higher resistance to surface regeneration conditions. After immobilizing single-domain antibodies on sensor surfaces sensing human
prostate-specific antigen
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted b ...
(hPSA) were tested. The nanobodies outperformed the classical antibodies in detecting clinical significant concentrations of hPSA.
To increase the
crystallization
Crystallization is the process by which solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposi ...
probability of a target molecule, nanobodies can be used as crystallization
chaperones. As auxiliary proteins, they can reduce the conformational heterogeneity by binding and stabilizing just a subset of conformational states. They also can mask surfaces interfering with the crystallization while extending regions that form crystal contacts.
Therapeutic
![Nanobodies for photothermal therapy](https://upload.wikimedia.org/wikipedia/commons/0/09/Nanobodies_for_photothermal_therapy.gif)
Single-domain antibodies have been tested as a new therapeutic tool against multiple targets. In mice infected with
influenza A virus subtype H5N1
Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus which can cause illness in humans and many other animal species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for highly pathogenic avian influenza virus of type ...
, nanobodies directed against
hemaglutinin
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 ...
suppressed replication of the H5N1 virus ''in vivo'' and reduced morbidity and mortality. Nanobodies targeting the cell receptor binding domain of the
virulence factor
Virulence factors (preferably known as pathogenicity factors or effectors in plant science) are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following ...
s toxin A and toxin B of ''
Clostridium difficile
''Clostridioides difficile'' (syn. ''Clostridium difficile'') is a bacterium that is well known for causing serious diarrheal infections, and may also cause colon cancer. Also known as ''C. difficile'', or ''C. diff'' (), is Gram-positive spec ...
'' were shown to neutralize cytopathic effects in
fibroblasts
A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells o ...
''in vitro''. Nanobody conjugates recognizing antigen presenting cells have been successfully used for tumor detection or targeted antigen delivery to generate strong immune response.
Orally available single-domain antibodies against ''E. coli''-induced diarrhoea in piglets have been developed and successfully tested.
Other diseases of the
gastrointestinal 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 organ (biology), organs of the digestive syste ...
, such as
inflammatory bowel disease
Inflammatory bowel disease (IBD) is a group of inflammation, inflammatory conditions of the colon (anatomy), colon and small intestine, Crohn's disease and ulcerative colitis being the principal types. Crohn's disease affects the small intestine a ...
and
colon cancer
Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel mo ...
, are also possible targets for orally available single-domain antibodies.
Detergent-stable species targeting a surface protein of ''
Malassezia furfur
''Malassezia furfur'' (formerly known as ''Pityrosporum ovale'' in its hyphal form) is a species of yeast (a type of fungus) that is naturally found on the skin surfaces of humans and some other mammals. It is associated with a variety of dermat ...
'' have been engineered for use in anti-
dandruff
Dandruff is a skin condition that mainly affects the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, ...
shampoos.
As an approach for
photothermal therapy Photothermal therapy (PTT) refers to efforts to use electromagnetic radiation (most often in infrared wavelengths) for the treatment of various medical conditions, including cancer. This approach is an extension of photodynamic therapy, in which a p ...
nanobodies binding to the
HER2
Receptor tyrosine-protein kinase erbB-2 is a protein that in humans is encoded by the ''ERBB2'' gene. ERBB is abbreviated from erythroblastic oncogene B, a gene originally isolated from the avian genome. The human protein is also frequently refer ...
antigen, which is overexpressed in breast and ovarian cancer cells, were conjugated to branched gold nanoparticles (see figure). Tumor cells were destroyed photothermally using a laser in a test environment.
Caplacizumab
Caplacizumab (INN; trade name Cablivi) is a bivalent single-domain antibody (VHH) designed for the treatment of thrombotic thrombocytopenic purpura (TTP) and thrombosis.
This drug was developed by Ablynx NV. On 30 August 2018, it was approved i ...
, a single-domain antibody targeting
von Willebrand factor
Von Willebrand factor (VWF) () is a blood glycoprotein involved in hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thrombocytopen ...
is in
clinical trials
Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...
for the prevention of
thrombosis
Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thro ...
in patients with acute coronary syndrome. A
Phase II study examining ALX-0081 in high risk
percutaneous coronary intervention
Percutaneous coronary intervention (PCI) is a non-surgical procedure used to treat narrowing of the coronary arteries of the heart found in coronary artery disease. The process involves combining coronary angioplasty with stenting, which is the ...
has started in September 2009.
Ablynx
Ablynx is a subsidiary of biopharmaceutical company Sanofi engaged in the discovery and development of nanobodies, based in Science Park Zwijnaarde, Ghent.
History
In November 2001, Ablynx was established as a spin-off of the Vlaams Instituut v ...
expects that their nanobodies might cross the
blood–brain barrier
The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...
and permeate into large solid tumours more easily than whole antibodies, which would allow for the development of drugs against
brain cancers
A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and secondar ...
.
Nanobodies that tightly bind to the RBD domain of the spike protein of betacoronaviruses (including
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 ...
which causes
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 ...
) and blocks interactions of spike with the cell receptor ACE2, has been recently identified
Application of various single domain antibodies (nanobodies) for the prevention and treatment of infection by various highly pathogenic human coronaviruses (HPhCoVs) has been reported. The prospects, potency and challenges of deploying nanobodies to bind and neutralize SARS-CoV-2 and akin have been recently highlighted.
One of the most common causes of
nagana
Animal trypanosomiasis, also known as nagana and nagana pest, or sleeping sickness, is a disease of vertebrates. The disease is caused by trypanosomes of several species in the genus ''Trypanosoma'' such as ''Trypanosoma brucei''. ''Trypanosoma ...
– ''
Trypanosoma brucei brucei
''Trypanosoma brucei'' is a species of parasitic kinetoplastid belonging to the genus ''Trypanosoma'' that is present in sub-Saharan Africa. Unlike other protozoan parasites that normally infect blood and tissue cells, it is exclusively extracellu ...
'' – can be targeted by sdAbs. Stijlemans et al 2004 succeeded in inducing effective sdAbs from
rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit speci ...
and ''
Camelus dromedarius
The dromedary (''Camelus dromedarius'' or ;), also known as the dromedary camel, Arabian camel, or one-humped camel, is a large even-toed ungulate, of the genus ''Camelus'', with one hump on its back.
It is the tallest of the three species of ...
'' by displaying a
variable surface glycoprotein
Variant surface glycoprotein (VSG) is a ~60kDa protein which densely packs the cell surface of protozoan parasites belonging to the genus ''Trypanosoma''. This genus is notable for their cell surface proteins. They were first isolated from ''Trypa ...
antigen to the vertebrates' immune systems using a phage. In the future, these therapies will surpass natural antibodies by reaching locations currently unreachable due to natural antibodies' larger size.
References
External links
Molecule of the Month: Nanobodies from the
Protein Data Bank
The Protein Data Bank (PDB) is a database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The data, typically obtained by X-ray crystallography, NMR spectroscopy, or, increasingly, cry ...
{{Engineered antibodies
.