Final answer:
HIV infects host cells by binding to the CD4 receptor and a coreceptor, typically CCR5 or CXCR4, on the cell's surface. This binding is essential for viral entry and subsequent replication within the host cell.
Step-by-step explanation:
The Human Immunodeficiency Virus (HIV) initiates replication by binding to two specific proteins on the surface of a host cell. These proteins are the CD4 receptor, a glycoprotein on the surfaces of T cells, and a coreceptor, which can be either CCR5 or CXCR4. These receptors are crucial for the entry of HIV into the host cells, as the virus attaches itself to the CD4 receptor and the coreceptor, facilitating the fusion of the viral envelope with the cell membrane and the subsequent release of the viral contents into the host cell.
After initially binding to these proteins, the viral envelope fuses with the cell membrane, and the process of converting HIV's single-stranded RNA into double-stranded viral DNA (VDNA) begins. This process, mediated by viral enzymes such as reverse transcriptase and integrase, eventually leads to the integration of the VDNA into the host cell's genome, which can remain dormant or lead to active production of new viruses.