HIV-1 PROTEASE DOES NOT PLAY A CRITICAL ROLE IN THE EARLY STAGES OF HIV-1 INFECTION

We asked whether human immunodeficiency virus type 1 (HIV-1) protease plays a major role in the early stages of infection (i.e. from viral e ntry to reverse transcription) by using various protease inhibitors (s aquinavir, ritonavir, and KNI-272). When assessed in the two-day multi nuclear activation of a galactosidase indicator (MAGI) assay, involvin g a single cycle of HIV-1 replication, all protease inhibitors failed to block infection of HeLa-CD4-LTR-beta-gal cells by HIV-1, while reve rse transcriptase (RT) inhibitors (AZT and ddI) completely blocked the infection. Moreover, when HIV-1 proviral DNA synthesis was examined b y polymerase chain reaction in HeLa-CD4-LTR-beta-gal cells exposed to HIV-1 and cultured in the presence of protease inhibitors, a significa nt amount of proviral DNA was detected, while no proviral DNA synthesi s was detected when the cells were cultured in the presence of RT inhi bitors. Protease inhibitors also failed to block chloramphenicol acety ltransferase (CAT) expression in HLCD4-CAT cells exposed to HIV-1, whi le RT inhibitors completely suppressed CAT expression. These results s trongly suggest, contrary to a previous report by Nagy et al. (1994), that HIV-1 protease does not play a major role in the early stages of infection. (C) 1997 Elsevier Science B.V.