Identification of a clinical isolate of HIV-1 with an isoleucine at position 82 of the protease which retains susceptibility to protease inhibitors

The HIV-1 protease (PR) is essential for the production of mature virions. As such, it has become a target for the development of anti-HIV chemotherapeutics. Multiple passages of virus in cell culture in the presence of PR inhibitors have resulted in the selection of variants with decreased sensitivity to inhibitors of the PR. The most common alteration observed is a single amino acid change at position 82. This particular position has been well characterized by several laboratories as being important for the susceptibility of the virus to inhibitors of PR function. Mutations which result in the substitution of the wild-type valine with alanine, phenylalanine, threonine or isoleucine at position 82 of the PR have been associated with decreased sensitivity to several PR inhibitors. We describe here a clinical strain of HIV-1 that contains an isoleucine at position 82 of the PR instead of the usual valine. This strain is unique in that it was isolated from a patient that was anti-retroviral naive, and in the past, variants at position 82 of the PR have only been found after treatment of patients or cell culture with PR inhibitors. Moreover, this virus remains sensitive to PR inhibitors of the cyclic urea and C-2 symmetrical diol classes.