Transmission of human immunodeficiency virus type 1 resistant to nevirapine and zidovudine. Sydney Primary HIV Infection Study Group.

Human immunodeficiency virus type 1 (HIV-1) resistant to the nonnucleoside reverse transcriptase inhibitor nevirapine and to the nucleoside analogue zidovudine was transmitted from a homosexual man to his sex partner. The virus source patient had commenced combination zidovudine and nevirapine therapy 2.5 years prior to his partner's primary HIV infection. He received both therapies for 7 months, then discontinued nevirapine treatment, continuing to receive zidovudine monotherapy for a further 16 months. He had ceased zidovudine therapy 6 months before the time of his partner's seroconversion. Analysis of major and minor isolates obtained from both patients soon after onset of the recipient's primary HIV infection illness confirmed that an HIV-1 variant mutant at codons 70, 98, and 181 of the viral reverse transcriptase was transmitted. This is the first documented case of transmission of HIV-1 resistant to two antiretroviral compounds.