Background: In this study, human immunodeficiency virus type 1 (HIV-1)-infected blood donors were evaluated for genetic subtype and drug resistance to determine the prevalence of divergent HIV strains in the US donor population.
Study design and methods: Subtype was determined by phylogenetic analysis of viral sequences amplified by reverse transcription-polymerase chain reaction. The drug resistance profile of the protease and reverse transcriptase (RT) genes was determined using an HIV-1 genotyping system (ViroSeq).
Results: From 1999 through 2005, 26 recently infected donors, defined as HIV-1 RNA-positive, antibody-negative (RNA+/Ab-), were identified (yield, 1:1.61 million). Over the same period, the frequency of anti-HIV-positive donors was 1:34,700. Twenty RNA+/Ab- specimens were evaluated; all were infected with HIV-1 subtype B. Drug resistance profiles obtained for 18 donors identified one strain with protease mutation L90M that confers resistance to nelfinavir and one with RT mutation Y188H that confers resistance to nevirapine. Genetic subtype was determined for 44 of 46 HIV antibody-reactive and confirmed-positive (Ab+) specimens. Three infections (6.8%) were due to circulating recombinant forms: 2 CRF01_AE and 1 CRF02_AG. In the Ab+ group, one strain was resistant to all nucleoside RT inhibitors and one had mutations that confer resistance to protease inhibitors.
Conclusion: The data show that antiretroviral drug-resistant HIV strains are being transmitted in the United States. Overall 6.5 percent (4 of 62) of HIV-1-infected donors harbored drug-resistant strains. HIV-1 non-B strains accounted for 4.7 percent (3 of 64) of the infections in donors. HIV-1 subtype B is still the predominant strain in the United States; however, non-B strains are increasing.