IMPAIRED INFECTIVITY OF HIV-1 AFTER A SINGLE-POINT MUTATION IN THE POL GENE TO ESCAPE THE EFFECT OF A PROTEASE INHIBITOR IN-VITRO

To examine whether the mutation of protease in an HIV-1 resistant to a protease inhibitor affects the virus phenotype in vitro, the infectiv ity of the protease inhibitor-escape-virus was compared to that of the parent virus. In different T-cell lines, the infectivity of the escap e virus was impaired by 10-fold compared to the parent virus. MT-4 cel l killing by the escape virus, measured using the MTT assay, was much weaker than that by the parent virus. The escape virus contained more unprocessed Pr55(gag) than the parent virus. A delayed appearance of m ature p24 in cells chronically infected with the escape virus was also noticed by the pulse-chase method. The same findings were obtained us ing pNL432 (HIV-1 DNA molecular clone) with the same mutation in the p rotease gene. Despite the lack of a significant difference in virus bi nding, less unintegrated and integrated DNA was detected in MT-4 cells infected with the escape virus compared to the parent virus. The impa ired infectivity of the escape virus may be explained by the inefficie nt maturation of Gag proteins, due to the mutated protease, which may affect an early step in the virus life cycle. (C) 1995 Academic Press, Inc.