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Session 65 Poster Session Antiretroviral Chemotherapy in Resource Limited Settings Session Time: 4:30-6:30 pm Room 4E-F

461-W. Genotypic and Phenotypic Analyses of Drug Susceptibility in HIV-1 Isolates from Drug-Naïve Patients in Nigeria S. M. Agwale*1, C. Zeh2, E. Paxinos3, L. Odama1, D. Pienazek2, C. Wambebe1, M. L. Kalish2, and R. Ziermann3 1Natl. Inst. for Pharmaceutical Res. and Development, Abuja, Nigeria; 2CDC, Atlanta, GA; 3ViroLogic Inc., South San Franciso, CA; and 4Bayer Diagnostics, Emeryville, CA Background: One of the major concerns in the AIDS pandemic is the extensive genetic variability of HIV-1. This affects the development of candidate vaccines and may impact antiretroviral therapy. Methods: Env subtype was determined using a modified gp41-based heteroduplex mobility assay. A 1.2-KB fragment in the pol gene (spanning the entire protease [PR] region and most of the reverse transcriptase [RT] region) were isolated and cloned into retroviral expression vectors. The sensitivity of the resultant PR and RT proteins to all available antiretroviral drugs was assayed using a version of Virologic's PhenoSense HIV assay modified for assaying non-B subtypes. Results: Analysis of HIV-1 PR and RT positions associated with mutations conferring resistance to antiretroviral drugs revealed no known primary resistance-associated mutations. For example, compared with the NL4_3 consesus sequence, we found between 9 and 17 amino acid substitutions within the protease region, all of which would be classified as secondary mutations or polymorphisms. All but one isolate were susceptible to all of the 15 drugs analyzed. This isolate exhibited low-level reductions in susceptibility to nelfinavir (3.8-fold) and ritonavir (3.4-fold) relative to the drug-sensitive control. Relative to our NL4_3-based reference, this isolate exhibited the following PR genotype: L10I, I13V, K14R, I15I/V, K20I, E35Q, M36I, N37D, R41K, R57K, L63L/P, I64I/M, C67E, H69K, T74T/S, V82I, and L89M. From the gp41-based heteroduplex assay, 17 of the 18 patients were infected with subtype G, and one patient was infected with subtype A. From phylogenetic analyses of 1212 nucleotides of pol, 13 of the 17 isolates were strongly grouped with other subtype G reference strains throughout PR and RT regions. One of these was more distinct from the rest, although it is more closely related to subtype G strains than to any other subtypes. Of the remaining 4 samples, 1 most closely resembled CRF_02_AG, while the 3 others (including the 1 sample with a subtype A env designation) were sister taxa to the CRF_02_AG clade. These 3 isolates are recombinants with varying degrees of G and A subtype fragments within PR and RT. Conclusions: Based on our analyses, subtype G and CRF_02_AG were susceptible to all classes of antiretroviral drugs and should respond to HAART regimens.

©2002 9th Conference on Retroviruses and Opportunistic Infections