HIV is a single-stranded RNA virus belong to the family Retrovirus and subfamily Lentivirus. HIV is divided into HIV-1 and HIV-2 types. AIDS around the world is mainly caused by HIV-1 type. HIV-2 is endemic in West Africa. HIV-1 can be further divided into subtypes, including subtype M(major subtype group), subtype O, and subtype N groups. HIV is a 20-sided stereosymmetric spherical partical with a spike structure on the surface of the glycoprotein, about 100 nm in diameter, which is divided into two parts: the capusule and the core. Outside the core is the viral capsid protein (P24, P17). After HIV infection, P24 antigen is an etiological marker that can be detected from serum earlier, which can be detected about 2-3 weeks after infection, enters the antigen peak about 1-2 months later, and then forms antigen-antibody complexes with the production of antibodies. Due to the neutralizing effect of antibodies, the P24 antigen concentration decreases to a level that is difficult to detect. Detection of P24 antigen (viral capsid protein) directly correlates with viral load in the circulatory system of infected individuals. The outermost layer of the virus is the envelope, in which an outer glycoprotein (gp120) and a transmembrane glycoprotein (gp41) are enbeded. The transmembrane protein is gp41 for HIV-1 and gp36 for HIV-2.
HIV recombinant antigen
HIV p24, gp36, and gp41 are markers of HIV infection. It can be detected within 2-8 weeks of the first exposure and has been detected in blood since then.