Each genomic RNA in HIV-1 heterozygous virus generate new virions

Retrovirus are unique because they present two complete copies of the genomic RNA in each virion. It is believed that only one proviral DNA is formed from the two genomic RNAs. To check this hypothesis, we constructed two deleterious HIV-1 variants in gag gene which upon transfection in Cos-1 cells were able, by complementation, to form heterozygous viruses, used to infect MT4 cells in a plaque assay. Analysis of the proviral DNA of the eight plaques obtained indicated that five were recombinants between the two deleterious mutants. Three other plaques showed three bands corresponding to the reverse transcription of both strands of one heterozygous virion and to the recombination of the two genomes. These results demonstrate that the two genomic RNAs in HIV-1 heterozygous virions could be used in the generation of new viruses. This mechanism permits the recovery of deleterious mutants and enhances the evolutive potential of HIV-1.