EXTENSIVE REGIONS OF POL ARE REQUIRED FOR EFFICIENT HUMAN-IMMUNODEFICIENCY-VIRUS POLYPROTEIN PROCESSING AND PARTICLE MATURATION

Human Immunodeficiency type 1 particle maturation is dependent upon pr oteolytic cleavage of the gag and gag-pol precursors by the pol-encode d viral protease. We have investigated the importance of domains of po l other than the protease for particle maturation and gag proteolytic processing. Truncations of the gag-pol polyprotein precursor of HIV-1 were created by deleting segments of the reverse transcriptase coding region or by introducing stop codons in the integrase region of an HIV -1 infectious molecular clone. In these mutants, the protease coding s equence was left intact. Particles produced by all of the mutants disp layed abnormal morphologies and impaired proteolytic processing of gag . The severity of particle morphology abnormalities and of gag polypro tein processing impairment appeared to be affected both by the size an d by the position of the deletions in pol, suggesting that the integri ty of several pol domains within the gag-pol precursor is required for optimal protease activation and particle maturation. Additionally, co transfection of a deletion mutant with wild-type provirus led to a mar ked reduction in the titer of infectious virus, suggesting that trunca ted gag-pol precursors can interfere with wild-type virus assembly and maturation. (C) 1996 Academic Press, Inc.