Page 9 - AIDSBK23C
P. 9
Page 9
The genome of HIV, similar to retroviruses in general, contains three major genes--gag,
pol, and env. These genes code for the major structural and functional components of HIV,
including envelope proteins and reverse transcriptase. The structural components encoded by
env include the envelope glycoproteins: outer envelope glycoprotein gp120 and transmembrane
glycoprotein gp41 derived from glycoprotein precursor gp160. Components encoded by the gag
gene include core nucleocapsid proteins p55, p40, p24 (capsid, or “core" antigen), p17 (matrix),
and p7 (nucleocapsid); the important proteins encoded by pol are the enzyme proteins p66 and
p51 (reverse transcriptase), p11 (protease), and p32 (integrase). [22,29,30]
Although most of the major HIV viral proteins, which include p24 (core antigen) and
gp41 (envelope antigen), are highly immunogenic, the antibody responses vary according to the
virus load and the immune competence of the host. The antigenicity of these various
components provides a means for detection of antibody, the basis for most HIV testing.[32]
A diagrammatic representation of HIV is shown below:
The viral genome for HIV-1 is shown below:
Accessory genes carried by HIV include tat, rev, nef, vif, vpr, and vpu (for HIV-1) or vpx
(for HIV-2). The rev gene encodes for a regulatory protein which switches the processing of
