Cotransfection of mutated forms of human immunodeficiency virus type 1 Gag-Pol with wild-type constructs can interfere with processing and viral replication.

OBJECTIVES: We wished to generate a number of genetic constructs containing mutations in the protease (PR) and reverse transcriptase (RT) genes of the Gag-Pol of human immunodeficiency virus type 1 (HIV-1) and to transfect these constructs into COS-7 cells to determine their effect on wild-type (wt) viral replication.
RESULTS: The mutated Gag-Pol polyproteins were incorporated into viral particles. Gag-Pol proteins that were mutated in PR as well as combinations of mutations in PR and RT inhibited the production of fully processed and infectious viral particles when these constructs were coexpressed with the infectious HIV-1 molecular clone pBH10. Viral particles produced after cotransfection of COS-7 cells with both pBH10 and infectious constructs containing Gag-Pol, mutated in PR alone or in both RT and PR, showed abnormal processing and lower infectivity. Complementation experiments in which pBH10 mutated in PR was coexpressed with wt Gag-Pol showed that the latter could be incorporated into the viral particles that were generated. COS-7 cells stably transfected with Gag-Pol, mutated in PR or in both PR and RT, and subsequently transfected with pBH10, produced levels of p24 and RT activity that were substantially diminished in comparison with levels produced by cells transfected with wt pBH10 alone.
CONCLUSIONS: These results suggest that trans-dominant effects were potentially responsible for the observed inhibition of viral replication.