M-tropic viruses infect only CD4+ macrophages and not T cells.

Correct Answer: False
M-tropic viruses infect both CD4+ macrophages and T cells. M-tropic and T-tropic are isolates of HIV-1 that use CCR5 as a coreceptor. T-tropic infects CD4+ T cells and uses a CXCR4 coreceptor.