Letters to the Editor
To the Editor:
As antiretroviral therapy (ART) regimens containing nonnucleoside reverse transcriptase inhibitors (NNRTIs) have gained increasing favor as a result of their potent activity and favorable side effect profile, there has been a corresponding increase in NNRTI resistance mutations detected in plasma. In fact, NNRTI resistance among patients newly infected with HIV is increasing at a rate greater than protease inhibitor (PI) resistance.1,2 A better appreciation of the prevalence and persistence of resistant HIV in the female genital tract, including viruses with NNRTI-resistant mutations, may allow a better understanding of the sexual and vertical transmission of these viruses.
The study population consisted of 20 NNRTI-experienced HIV-positive women who receive medical care at The Miriam Hospital Immunology Center (Providence, RI). The Miriam Hospital Institutional Review Board approved the study. All the women gave written informed consent. The patients' history, counseling, and sexually transmitted disease (STD) screening records were obtained and testing had been performed as described previously.3 HIV-seropositive women failing ART with a plasma viral load greater than 10,000 copies/mL were eligible for enrollment.
HIV RNA was extracted from plasma, Sno-strips, and cervicovaginal lavage (CVL) samples using Qiagen reagents (Valencia, CA). Reverse transcription, polymerase chain reaction (PCR) amplification of HIV sequences, and sequencing of PCR products spanning the pol gene were accomplished using previously published methods.4 Sequences were analyzed using the HIVseq program5 from the Stanford University HIV drug resistance database. Quantitative viral load analysis from blood and genital compartments was performed by the Nuclisens assay.
Reverse transcriptase (RT) and protease sequences were amplified from the plasma and genital samples of 8 of the 20 NNRTI-experienced subjects. Thirty-eight percent of these patients were black, 25% were Hispanic, and 38% had a history of intravenous drug abuse. These 8 patients had an average CD4 count of 223 cells/μL. They have each taken at least 5 RT inhibitors, including azidothymidine (AZT), lamivudine (3TC), and at least 1 NNRTI. The average duration of ART was 6.9 years, and the average duration of NNRTI therapy was 1.6 years. Five of the 8 subjects were not taking NNRTIs at the time of analysis. These patients had not taken NNRTIs for an average of 1.3 years before this study.
NNRTI resistance mutations were detected in genital secretions of all patients (Table 1). Mutations at the major NNRTI resistance codon K103 were found in the plasma and genital tract of 5 subjects, whereas K238N mutations were found in the genital tract but not the plasma of 2 subjects who were not currently receiving NNRTI therapy. The 3TC resistance mutation M184V was detected in the plasma and genital compartments of 6 subjects, whereas the L63P protease gene polymorphism in plasma was found in both compartments of 7 subjects (data not shown). Virus from most paired samples had similar patterns of resistance; however, discordant mutations from the plasma and genital tract were also found in 5 of these 8 patients. Discordance between blood and genital HIV resistance may imply differing selective pressures in these sources. Compartmentalization between blood and the female genital tract has also been demonstrated by the findings of differing genotypic variants, genetic complexity, and drug resistance mutations from these sources.5-10 Reduced antiretroviral drug concentrations in genital tissues may contribute to selection of different viruses from these sources.11 Alternatively, the cellular environment of the female genital tract may result in different selective pressures compared with virus found in blood.
From this cohort of NNRTI-experienced women, mutations conferring NNRTI resistance were isolated from the genital tract of all subjects, including all 5 patients not currently on NNRTI therapy. The longest period analyzed off NNRTI therapy was 33 months, during which time the K238N mutation was detected in the genital tract (subject 20). The K103N mutation was detected in the plasma and genital tract in subject 4, who had not been on NNRTI treatment for 23 months. A recent report suggests that the K103N NNRTI resistance mutation is one of the most common HIV drug resistance mutations found during primary infection and that this variant can persist for years in the absence of drug selection.12 Our results suggest that NNRTI mutations also seem to be stable in the female genital tract in the absence of drug selection, implying that these viruses have a relatively preserved fitness in these settings. These findings highlight the potential for further increases in the sexual and vertical transmission of HIV resistant to NNRTI and have particular relevance to the design of treatment for pregnant women previously treated with NNRTI drugs.
The authors thank Fred Lee for expert technical assistance and Daniel Boden for helpful discussions.
*Division of Infectious Diseases, Department of Medicine, Brown Medical School, Providence, RI; and †Department of Pathology and Laboratory Medicine, School of Medicine, Emory University, Atlanta, GA
1. Grant RM, Hecht FM, Warmerdam M, et al. Time trends in primary HIV-1 drug resistance among recently infected persons. JAMA
2. Simon V, Vanderhoeven J, Hurley A, et al. Evolving patterns of HIV-1 resistance to antiretroviral agents in newly infected individuals. AIDS
3. Cu-Uvin S, Caliendo AM, Reinert S, et al. Effect of highly active antiretroviral therapy on cervicovaginal HIV-1 RNA. AIDS
4. Boden D, Hurley A, Zhang L, et al. HIV-1 drug resistance in newly infected individuals. JAMA
5. Shafer RW, Jung DR, Betts BJ. Human immunodeficiency virus type 1 reverse transcriptase and protease mutation search engine for queries. Nat Med
6. Kovacs A, Wasserman SS, Burns D, et al. Determinants of HIV-1 shedding in the genital tract of women. Lancet
7. Poss M, Martin HL, Kreiss JK, et al. Diversity in virus populations from genital secretions and peripheral blood from women recently infected with human immunodeficiency virus type 1. J Virol
8. Overbaugh J, Anderson RJ, Ndinya-Achola JO, et al. Distinct but related human immunodeficiency virus type 1 variant populations in genital secretions and blood. AIDS Res Hum Retroviruses
9. Si-Mohamed A, Kazatchkine MD, Heard I, et al. Selection of drug-resistant variants in the female genital tract of human immunodeficiency virus type 1-infected women receiving antiretroviral therapy. J Infect Dis
10. Leigh Brown AJ, Frost SD, Mathews WC, et al. Transmission fitness of drug-resistant human immunodeficiency virus and the prevalence of resistance in the antiretroviral-treated population. J Infect Dis
11. DePasquale MP, Brown AL, Cu-Uvin S, et al. Differences in HIV-1 pol sequences from female genital tract and blood during antiretroviral therapy. J Acquir Immune Defic Syndr
12. Little SJ, Koelsch KK, Ignacio CC. Persistence of transmitted drug-resistant virus among subjects with primary HIV infection deferring antiretroviral therapy. Presented at: 11th CROI; 2004; Boston.