A strain of HIV that enters and infects a host cell by binding to the CCR5 receptor on the host cell. To enter a host cell, HIV must first attach to a CD4 receptor, then attach to either the CCR5 or CXCR4 receptor, and finally fuse its membrane with the host cell membrane. HIV is usually R5-tropic (uses CCR5) during the early stages of infection, but the virus may later switch to using either only CXCR4 or both CCR5 and CXCR4. Antiretroviral (ARV) drugs in the CCR5 inhibitor drug class block HIV from attaching to the CCR5 receptor, preventing HIV entry into the host cell.