Mutant viruses HIV-1-AP-1#3mut, HIV-1-AP-1#1mut, HIV-1-AP-1#1+2mut and HIV-1-AP-1#totmut exhibited a similar behaviour than previously measured in p24 assays since we observed a 48%, 52%, 39% and 40% (17%, 54%, 37% and 52%) decrease of elongated transcripts in Jurkat (U937) cells at day 15 post-infection. This evidence concerns the gene FOS and infection.