HIV 12 – Life Cycle

1. ENTRY INHIBITORS stop the virus from entering the CD4 cell (Step 2) e.g. maraviroc (MVC).
2. NUCLEOS(T)IDE REVERSE TRANSCRIPTASE INHIBITORS act as fake substrates and stop the DNA forming in Step 3 e.g. abacavir (ABC), didanosine (ddI),
   emtricitabine (FTC), lamivudine (3TC), stavudine (d4T), zidovudine (AZT) and tenofovir (TDF).
3. NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS stop the enzymes from working in Step 3 e.g. efavirenz (EFV), etravirine (ETV), nevirapine (NVP) and rilpivirine (RPV).
4. INTEGRASE STRAND INHIBITORS stop the HIV from being added into the cell’s DNA (Step 4) e.g. dolutegravir (DTG) and raltegravir (RAL).
5. PROTEASE INHIBITORS stop the ‘cutting up’ needed to make new HIV in Step 6 e.g. atazanavir (ATV), darunavir (DRV), fosamprenavir (FPV), lopinavir/ritonavir (LPV/r), ritonavir (RTV) and saquinavir (SQV).

1. BINDING: HIV makes its way to the body’s CD4 cells – the cells that fight infection – and the virus attaches to the outer wall of the cell.

2. FUSION: The virus fuses (joins together) with the CD4 cell, enters it and releases its contents (HIV RNA, where it carries its genes, and proteins/enzymes which will help to make more HIV) inside the CD4 cell.

*Fusion and entry inhibitors are HIV medicines (ARVs) that block this step of the HIV lifecycle.

3. REVERSE TRANSCRIPTION: One of the released viral materials is a protein called reverse transcriptase that allows the virus’s genetic material to change from HIV RNA to HIV DNA.

*The nucleoside/nucleotide reverse transcriptase inhibitors and non-nucleoside reverse transcriptase inhibitors are ARVs that block this step, stopping multiplication of the virus.

4. INTEGRATION: The HIV DNA travels to the nucleus (the ‘heart’) of the CD4 cell where it uses another viral material, integrase, to combine the HIV DNA to the CD4 cell DNA *The integrase inhibitors are ARVs that block this step, stopping the virus from making more of itself.
5. REPLICATION: Once HIV and CD4 cell DNA have combined, HIV uses the CD4 cell’s machinery to produce long chains of HIV proteins. The HIV proteins are the building blocks of the new virus. *New ARVs are being developed to block this step, stopping the virus from making more of itself, e.g., lenacapavir.
6. ASSEMBLY: The newly formed HIV proteins, including HIV RNA, travel to the surface of the CD4 cell and assemble (gather together) to form two immature viruses. Another one of the initially released viral materials, protease, cuts up these assem­bled long HIV protein chains to produce mature viruses.

*Proteases inhibitors are ARVs that block this step of the HIV lifecycle, stopping the virus from making more of itself.

7. BUDDING: The new mature HIV pushes out of the CD4 cell and the CD4 cell dies. This new HIV then moves into another CD4 cell, and the process starts again.