PCR analysis of HIV1 infection of macrophages: virus entry is CD4-dependent

Amplification of early reverse transcripts by the polymerase chain reaction has been used to measure HIV1 entry into H9 cells and primary macrophages. With a single-step method of DNA preparation, we performed time course experiments to follow the appearance of long terminal repeat DNA. In both cell types, the formation of DNA was completely inhibited by anti-CD4 antibody, confirming the requirement of CD4 for virus binding and entry, and demonstrating that there were no CD4-independent routes of infection. In agreement with previous infectivity studies, sCD4 inhibited the entry of IIIB into H9, but only partially blocked Ba-L into macrophage when used at a comparable dose.