Table 1.
HIV-1 main genes and protein functions encoded.
| Class | Gene | Polyprotein | Protein(s) | Function(s) | References |
|---|---|---|---|---|---|
| Viral structural proteins | gag | Gag | Matrix (MA, p17) Capsid (CA, p24) Nucleocapsid (NC, p7) |
Encodes a polyprotein that is processed to form the structural proteins placed inside the envelope | [23, 24] |
| pol | Pol | Protease (PR, p12) Reverse transcriptase (RT, p66) and RNaseH (p51) Integrase (IN, p32) |
Proteolytic cut of Gag/Pol proteins. When in the cytoplasm, RT transcribes viral RNA into a complementary copy of DNA, resulting in the formation of dsDNA. RNaseH degrades viral RNA. In the nucleus, the integration of HIV dsDNA occurs into the host cellular genome by IN (formation of the provirus) |
[24, 25] | |
| env | PrGp (gp160) | Surface protein (SU, gp120) Transmembrane protein (TM, gp41) |
It fuses the viral and cell membranes after binding to the cellular receptor; gp160 undergoes a series of conformational changes, and it is cleaved in gp120 and gp41 | [24, 26] | |
|
| |||||
| Essential regulatory elements | tat | — | Tat | Transactivator; activates transcription of viral DNA and cellular genes | [27] |
| rev | — | Rev | Gene transcription regulator of virion proteins. Rev facilitates viral unspliced mRNAs transport from the nucleus to the cytoplasm for their translation | [25] | |
|
| |||||
| Accessory regulatory proteins | nef | — | Negative regulating factor | Nef is a protein that affects HIV replication, viral particle infectivity, CD4 downregulation and apoptosis | [24] |
| vif | — | Viral infectivity factor | Vif regulates virus infectivity through the degradation of human APOBEC3G (cellular cytidine deaminase) protein, which provide innate immunity against various pathogens | [28] | |
| vpr | — | Viral protein R | Vpr controls the import of the HIV-1 dsDNA preintegration complex into the nucleus, the activation and apoptosis of infected cells, virus transcription, and cell cycle arrest | [29] | |
| vpu | — | Viral protein U | Vpu increases the release of viral particles from human cells and contributes to the overall downregulation of CD4s expression throughout HIV-1 infection by inducing their degradation | [30] | |