CAN DRUG-RESISTANT VARIANTS OF HIV BE TRANSMITTED?
There is no direct evidence to date to suggest that drug-resistant strains of HIV are more transmissible than wild-type viruses and, in fact, the opposite conclusion can be inferred from the work cited above on transmission of AZT-resistant strains in primary infection between 1989 and 1995 (13). Otherwise, one would have expected to see a steady climb in the percentage of cases of primary transmission associated with mutations that confer resistance to ZDV during this period. Further, some data suggest that AZT-resistant strains may, in fact, be marginally impaired in regard to replication competence (18). In addition, viruses containing the M184V mutation, associated with resistance to 3TC, have been shown to be less replication-fit than wild type viruses in primary cells, e.g., peripheral blood mononuclear cells, although both types of viruses may multiply equally well in a variety of T cell lines (19,20). One case of sexual transmission of HIV resistant to both AZT and nevarapine h
