HUMAN IMMUNODEFICIENCY VIRUS P24 PROTEIN [HIV-1/CLADE B]

Recombinant HIV-1 p24 protein (clade B) is produced in mammalian cells and fused with a C-terminal His-tag.

PRODUCT DETAILS – HUMAN IMMUNODEFICIENCY VIRUS P24 PROTEIN [HIV-1/CLADE B]

• Recombinant HIV p24 protein (NCBI accession number ABO61536, AA35-265, L40I) produced in HEK293 cells.
• Protein contains a C-terminal 6x His-tag and was purified by immobilised metal affinity and ion exchange chromatography from the pellet of transfected cells.
• HIV-1 p24 protein (clade B) presented in Dulbecco’s phosphate buffered saline (DPBS) pH 7.8.

BACKGROUND

Human immunodeficiency virus (HIV) is a retrovirus (genus Lentivirus) with a single-stranded, positive-sense RNA genome. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase allowing the genome to be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated to infect other cells. Infection with HIV leads to a condition in which the immune system begins to fail, leading to opportunistic infections. HIV primarily infects cells in the human immune system including CD4 T cells, macrophages and dendritic cells. Infection subsequently results in low levels of CD4 T cells via direct viral killing of infected cells, increased rates of apoptosis in infected cells and killing of infected CD4 T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4 T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.

The gag gene of HIV-1 encodes a precursor protein known as Pr55^Gag. The viral protease PR cleaves this precursor to generate p17, p24, p7, and p6 proteins which are required for virus particle assembly. p24 is a major viral core structural protein. Its measurement is commonly used as an indicator of HIV-1 infection and viral load. P24 is a 24–25 kDa protein and present at high copy number in HIV-1 virions. The onset of symptoms of AIDS correlates with increased levels of virus and p24 in the blood and a reduction in the number of CD4 T-cells which can be detected as early as 2 weeks after HIV infection using immunoassays. Decrease in the level of antibodies to p24 and p24 antigen has been considered to be one of the most useful prognostic markers for use in assays. Fourth-generation tests can now detect both HIV antibodies and p24 antigens, whereas older versions only looked for antibodies, resulting in a quicker diagnosis compared to previous generation tests. Most diagnostic kits to detect HIV antibodies incorporate p24, in addition to envelope glycoproteins.

REFERENCES

• Coffin JM, Hughes SH, Varmus HE. Retroviruses. Cold Spring Harbor Laboratory Press; 1999.
• Gray et al. (2018). p24 revisited: a landscape review of antigen detection for early HIV diagnosis. AIDS. 32(15):2089-2102.
• Kwong et al. (2013). Broadly neutralizing antibodies and the search for an HIV-1 vaccine: the end of the beginning. Nature Reviews Immunology, volume 13, pages 693–701.