Broad nucleoside-analogue resistance implications for human immunodeficiency virus type 1 reverse-transcriptase...

Area of Science:

• Virology
• Molecular Biology
• Pharmacology

Background:

• Human immunodeficiency virus type 1 (HIV-1) treatment relies on nucleoside reverse transcriptase inhibitors (NRTIs).
• Emergence of drug resistance, particularly in the reverse transcriptase (RT) enzyme, is a major challenge in HIV-1 therapy.
• Specific amino acid substitutions in RT can confer resistance to multiple NRTIs.

Purpose of the Study:

• To analyze the epidemiology of amino acid substitutions at codons 44 and 118 in HIV-1 RT.
• To understand the association of these substitutions with other known resistance mutations.
• To evaluate the impact of these substitutions on susceptibility to various NRTIs.

Main Methods:

• Analysis of two large, independent HIV-1 RT sequence databases (>7700 sequences).
• Epidemiological analysis of amino acid substitutions at codons 44 and 118.
• Site-directed mutagenesis to confirm phenotypic effects of mutations.

Main Results:

• Substitutions E44A/D and V118I were strongly associated with established NRTI resistance mutations (M41L, D67N, L210W, T215Y) and others.
• E44D and V118I showed frequent association with stavudine and didanosine, but also with zidovudine and lamivudine.
• These mutations were selected even with switches to other NRTIs like zalcitabine and abacavir.
• Site-directed mutagenesis confirmed reduced susceptibility to lamivudine, stavudine, and abacavir.

Conclusions:

• Substitutions at RT codons 44 and 118 contribute to broad nucleoside reverse transcriptase inhibitor resistance.
• These mutations have significant implications for HIV-1 treatment regimens involving multiple NRTIs.
• Understanding these resistance pathways is crucial for optimizing HIV therapy.