title: HIV-1 protease does not play a critical role in the early stages of HIV-1 infection.
abstract: 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 entry to reverse transcription) by using various protease inhibitors (saquinavir, ritonavir, and KNI-272). When assessed in the two-day multinuclear activation of a galactosidase indicator (MAGI) assay, involving 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 reverse transcriptase (RT) inhibitors (AZT and ddI) completely blocked the infection. Moreover, when HIV-1 proviral DNA synthesis was examined by polymerase chain reaction in HeLa-CD4-LTR-beta-gal cells exposed to HIV-1 and cultured in the presence of protease inhibitors, a significant amount of proviral DNA was detected, while no proviral DNA synthesis was detected when the cells were cultured in the presence of RT inhibitors. Protease inhibitors also failed to block chloramphenicol acetyltransferase (CAT) expression in HLCD4-CAT cells exposed to HIV-1, while RT inhibitors completely suppressed CAT expression. These results strongly 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.
authors.affiliation: The Experimental Retrovirology Section, Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: H
authors.initials: H
authors.lastname: Uchida
authors.forename: Y
authors.initials: Y
authors.lastname: Maeda
authors.forename: H
authors.initials: H
authors.lastname: Mitsuya
mesh_terms: D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D015658:HIV Infections; D016333:HIV Protease / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D019438:Ritonavir / Q000494:pharmacology*; D019258:Saquinavir / Q000494:pharmacology*
chemical_list: D017320:HIV Protease Inhibitors; D009842:Oligopeptides; D015500:Chloramphenicol O-Acetyltransferase; D016333:HIV Protease; D019258:Saquinavir; C077822:kynostatin 272; D019438:Ritonavir