Which class of HIV drugs blocks viral entry by binding to the CCR5 receptor?

• A. NNRTIs
• B. NRTIs
• C. CCR5 receptor antagonists
• D. Integrase inhibitors

Answer: (C)

The key idea is how some HIV drugs prevent the virus from getting into host cells by targeting the CCR5 co-receptor. CCR5 receptor antagonists bind to CCR5 on the surface of CD4+ T cells, blocking the interaction needed for HIV to enter the cell. If HIV is using the CCR5 pathway (CCR5-tropic), this prevents gp120 from attaching and fusing, so viral entry is halted. A representative drug in this class is maraviroc. These drugs will not work if the virus uses CXCR4 or is dual-tropic, and they do not affect the reverse transcription step inside the cell like other classes do. In contrast, nucleoside or non-nucleoside reverse transcriptase inhibitors block reverse transcription, and integrase inhibitors prevent integration of viral DNA into the host genome; neither blocks entry via the CCR5 receptor.