To assess whether the CIITA-mediated inhibition of Tat function observed in CIITA-positive U937 cells was correlated with an inhibition of HIV-1 replication we infected the different U937 clones with HIV-1IIIB/LAI and measured the levels of RT viral activity in the culture supernatants up to 41 days post-infection. The gene discussed is CIITA; the disease is infection.