NAEGER LK, WHITE KL, MARGOT N, TUSKE S, SARAFIANOS S, ARNOLD E, MILLER M; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. I-1755.

Gilead Sciences, Foster City, CA

BACKGROUND: HIV-1 RT-mediated removal of nucleoside chain-terminators by ATP-dependent chain-terminator removal is a proposed mechanism of NRTI resistance. METHODS: Recombinant HIV-1 wild-type RT and a mutant RT enzyme containing the thymidine analog resistance mutations D67N/K70R/T215Y were analyzed for their ability to remove the chain-terminators, zidovudine, stavudine, zalcitabine, didanosine, lamivudine, abacavir, DXG and tenofovir, in the presence of ATP. RESULTS: A comparison of ATP-dependent removal by the mutant RT demonstrated rates of removal in the following order: zidovudine > stavudine > zalcitabine > abacavir + DXG > lamivudine + didanosine + tenofovir. In additional experiments, the addition of ATP and the next complementary dNTP demonstrated a reduction of ATP-mediated removal of stavudine and zalcitabine; while zidovudine removal was unaffected. CONCLUSIONS: Our results confirm that HIV-1 RT can remove chain-terminators in the presence of physiological concentrations of ATP. This is a potential mechanism of NRTI resistance, most notably for zidovudine, stavudine, and zalcitabine. This effect for stavudine and zalcitabine can be moderated by the presence of dNTPs. Abacavir and DXG showed intermediate levels of removal. Tenofovir, didanosine and lamivudine were minimally removed under both conditions, consistent with the minor changes in HIV susceptibility for these drugs associated with thymidine analog resistance mutations. Crystallographic analysis of HIV-1 RT bound with a tenofovir-terminated primer-template suggests that achieving a conformation of tenofovir suitable for its removal may be disfavored by the relative flexibility of its acyclic linker and the non-canonical base pairing observed between tenofovir and the template. The inefficient removal of tenofovir may contribute to the durable anti-HIV activity observed in nucleoside-experienced patients treated with its oral prodrug, tenofovir disoproxil fumarate.

Publication Types:

• Meeting Abstracts

Keywords:

• Acquired Immunodeficiency Syndrome
• Adenine
• Anti-HIV Agents
• Didanosine
• Dideoxynucleosides
• HIV
• HIV Infections
• HIV-1
• Humans
• Lamivudine
• Mutation
• Nucleosides
• Phosphonic Acids
• Stavudine
• Thymidine
• Zalcitabine
• Zidovudine
• abacavir
• genetics
• reverse transcriptase, Human immunodeficiency virus 1
• tenofovir
• tenofovir disoproxil

Other ID:

• GWAIDS0029029

UI: 102268661

From Meeting Abstracts