The HIV viral cycle. Step 1: the HIV fuses to the host-cell surface. Specifically, the gp120 proteins on the surface of the virus binds to the CD4. This then binds to a smaller coreceptor (CCR5 or CXCR4). Step 2: HIV RNA, reverse transtriptase, integrase, and other viral proteins enter the host cell. The virus is brought into the host cell and uncoated; both viral RNA and reverse transcriptase are loosed into the cell. Step 3: Viral DNA is formed by reverse transcription. Step 4: Viral DNA is transported across the nucleus and integrates into the host DNA. Integrase found on the viral DNA. The viral DNA in the host DNA is called provirus. Step 5: New viral RNA is used as genomic RNA and to make viral proteins. New viral RNA strands are made and leave the nucleus. Step 6: New viral RNA and proteins move to the cell surface and a new immature HIV forms. The viral is assembled in an outbulging of the host cell. Step 7: The virus matures when protease releases the proteins that form the mature HIV. Mature virion is released.
