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P24 Capsid Protein
p24 is a component of the HIV particle capsid. There are approximately 2000 molecules per virus particle, or at a molecule weight of 24 kDa, about 104 virus particles per picogram of p24. The onset of symptoms of AIDS correlates with a reduction in the number of CD4+ T cells and increased levels of virus and p24 in the blood. It is a component of the ''gag'' polyprotein. Fourth-generation HIV test Fourth-generation HIV immunoassays detect viral p24 protein in the blood (as well as patient antibodies against the virus). Previous generation tests relied on detecting patient antibodies alone; it takes about 3–4 weeks for the earliest antibodies to be detected. The p24 protein can be detected in patient blood as early as 2 weeks after HIV infection, further reducing the window period necessary to accurately detect the HIV status of the patient. See also HIV vaccine An HIV vaccine is a potential vaccine that could be either a preventive vaccine or a therapeutic vaccine, which m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P24 HIV-capsid
P, or p, is the sixteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''pee'' (pronounced ), plural ''pees''. History The Semitic Pê (mouth), as well as the Greek Π or π ( Pi), and the Etruscan and Latin letters that developed from the former alphabet, all symbolized , a voiceless bilabial plosive. Use in writing systems In English orthography and most other European languages, represents the sound . A common digraph in English is , which represents the sound , and can be used to transliterate ''phi'' in loanwords from Greek. In German, the digraph is common, representing a labial affricate . Most English words beginning with are of foreign origin, primarily French, Latin and Greek; these languages preserve Proto-Indo-European initial *p. Native English cognates of such words often start with , since English is a Germanic language and thus ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsid
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid. Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picogram
To help compare different orders of magnitude, the following lists describe various mass levels between 10−59 kg and 1052 kg. The least massive thing listed here is a graviton, and the most massive thing is the observable universe. Typically, an object having greater mass will also have greater weight (see mass versus weight), especially if the objects are subject to the same gravitational field strength. Units of mass The table at right is based on the kilogram (kg), the base unit of mass in the International System of Units ( SI). The kilogram is the only standard unit to include an SI prefix (''kilo-'') as part of its name. The ''gram'' (10−3 kg) is an SI derived unit of mass. However, the ''names'' of all SI mass units are based on ''gram'', rather than on ''kilogram''; thus 103 kg is a ''megagram'' (106 g), not a *''kilokilogram''. The ''tonne'' (t) is an SI-compatible unit of mass equal to a megagram (''Mg''), or 103 kg. The unit is in common use for m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HIV/AIDS
Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual may not notice any symptoms, or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged incubation period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections such as tuberculosis, as well as other opportunistic infections, and tumors which are rare in people who have normal immune function. These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS). This stage is often also associated with unintended weight loss. HIV is spread primarily by unprotected sex (including anal and vaginal sex), contaminated blood transfusions, hypodermic needles, and from mother to ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD4+ T Cell
In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 (after the OKT4 monoclonal antibody that reacted with it) before being named CD4 in 1984. In humans, the CD4 protein is encoded by the ''CD4'' gene. CD4+ T helper cells are white blood cells that are an essential part of the human immune system. They are often referred to as CD4 cells, T-helper cells or T4 cells. They are called helper cells because one of their main roles is to send signals to other types of immune cells, including CD8 killer cells, which then destroy the infectious particle. If CD4 cells become depleted, for example in untreated HIV infection, or following immune suppression prior to a transplant, the body is left vulnerable to a wide r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group-specific Antigen
Group-specific antigen, or gag, is the polyprotein that contains the core structural proteins of an Ortervirus (except ''Caulimoviridae''). It was named as such because scientists used to believe it was antigenic. Now it is known that it makes up the inner shell, not the envelope exposed outside. It makes up all the structural units of viral conformation and provides supportive framework for mature virion. All orthoretroviral ''gag'' proteins are processed by the protease (PR or ''pro'') into MA (matrix), CA (capsid), NC (nucleocapsid) parts, and sometimes more. If Gag fails to cleave into its subunits, virion fails to mature and remains uninfective. It comprises part of the ''gag-onc'' fusion protein. Gag in HIV Numbering system By convention, the HIV genome is numbered according to HIV-1 group M subtype B reference strain HXB2. Transcription and mRNA processing After a virus enters a target cell, the viral genome is integrated into the host cell chromatin. RNA polymer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoassay
An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay is often referred to as an "analyte" and is in many cases a protein, although it may be other kinds of molecules, of different sizes and types, as long as the proper antibodies that have the required properties for the assay are developed. Analytes in biological liquids such as serum or urine are frequently measured using immunoassays for medical and research purposes. Immunoassays come in many different formats and variations. Immunoassays may be run in multiple steps with reagents being added and washed away or separated at different points in the assay. Multi-step assays are often called separation immunoassays or heterogeneous immunoassays. Some immunoassays can be carried out simply by mixing the reagents and sample and making a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 pathogen, called an antigen. Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can ''tag'' a microbe or an infected cell for attack by other parts of the immune system, or can neutralize it directly (for example, by blocking a part of a virus that is essential for its invasion). To allow the immune system to recognize millions of different antigens, the antigen-binding sites at both tips of the antibody come in an equally wide variety. In contrast, the remainder of the antibody is relatively constant. It only occurs in a few varia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Window Period
In medicine, the window period for a test designed to detect a specific disease (particularly infectious disease) is the time between first infection and when the test can reliably detect that infection. In antibody-based testing, the window period is dependent on the time taken for seroconversion. The window period is important to epidemiology and safe sex strategies, and in blood donation, blood and organ donation, because during this time, an infected person or animal cannot be detected as infected but may still be able to infect others. For this reason, the most effective disease-prevention strategies combine testing with a waiting period longer than the test's window period. Examples HIV HIV test#Window period, The window period for HIV may be up to three months, depending on the test method and other factors. RNA based HIV tests has the lowest window period. Modern and accurate testing abilities can cut this period to 25 days, 16 days, or even as low as 12 days, again, depe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HIV Vaccine
An HIV vaccine is a potential vaccine that could be either a preventive vaccine or a therapeutic vaccine, which means it would either protect individuals from being infected with HIV or treat HIV-infected individuals. It is thought that an HIV vaccine could either induce an immune response against HIV (active vaccination approach) or consist of preformed antibodies against HIV (passive vaccination approach). Two active vaccine regimens, studied in the RV 144 and Imbokodo trials, showed they can prevent HIV in some individuals. However, the protection was in relatively few individuals, and was not long lasting. For these reasons, no HIV vaccines have been licensed for the market yet. Difficulties in development In 1984, after it was confirmed that HIV caused AIDS, the United States Health and Human Services Secretary Margaret Heckler declared that a vaccine would be available within two years. However, priming the adaptive immune system to recognize the viral envelope protein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viral Structural Proteins
A viral structural protein is a viral protein that is a structural component of the mature virus. Examples include the SARS coronavirus 3a and 7a accessory proteins. Bacteriophage T4 structural proteins During assembly of the bacteriophage (phage) T4 virion, the structural proteins encoded by the phage genes interact with each other in a characteristic sequence. Maintaining an appropriate balance in the amounts of each of these structural proteins produced during viral infection appears to be critical for normal phage T4 morphogenesis. Phage T4 encoded proteins that determine virion structure include major structural components, minor structural components and non-structural proteins that catalyze specific steps in the morphogenesis sequence. Phage T4 morphogenesis is divided into three independent pathways: the head, the tail and the long tail fibres as detailed by Yap and Rossman.Yap ML, Rossmann MG. Structure and function of bacteriophage T4. Future Microbiol. 2014;9(12):131 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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