CONDITIONAL HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 PROTEASE MUTANTS SHOWNO ROLE FOR THE VIRAL PROTEASE EARLY IN VIRUS-REPLICATION

The human immunodeficiency virus type 1 protease plays a critical role in the proteolytic processing of precursor polyproteins during virion maturation, Contradictory evidence has been obtained for a possible r ole for the protease early after infection, i,e., during DNA synthesis and/or integration. We have reexamined this question by using conditi onal mutants of the protease. In one set of experiments, protease muta nts that cohfer a temperature-sensitive phenotype for processing were used to assess the need for protease activity early after infection. N o significant difference from results with wild-type virus was seen wh en infections were carried out at either 35 or 40 degrees C. In a sepa rate set of experiments, infections were carried out in the presence o f a protease inhibitor. In this case, both mild-type virus and a drug- resistant variant were used, the latter as a control to ensure a speci fic effect of the inhibitor. Infection with either virus was not inhib ited at drug concentrations that were up to 10-fold higher than those needed to inhibit intracellular processing by the viral protease. The results obtained by both of these experimental protocols provide evide nce that the human immunodeficiency virus type 1 protease does not pla y a role early after infection.