Altogether, these results demonstrate the importance of the intragenic AP-1 binding sites for efficient HIV-1 replication in macrophages as a decrease in viral expression of AP-1 site mutant viruses, and especially of the AP-1#2 site mutant virus, was detected in transduction of primary MDMs with VSV-G pseudotyped viruses (during single-round infections). The gene discussed is FOS; the disease is infection.