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Rapid Screening of HIV Reverse Transcriptase and Integrase Inhibitors
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Rapid Screening of HIV Reverse Transcriptase and Integrase Inhibitors

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Gln145Met/Leu changes in human immunodeficiency virus type 1 reverse transcriptase confer resistance to nucleoside

Stefania Paolucci1, Fausto Baldanti, Giovanni Maga

  • 1Servizio di Virologia, IRCCS Policlinico San Matteo, Pavia, Italy.

Antimicrobial Agents and Chemotherapy
|November 25, 2004
PubMed

Insights

Multidrug resistance mutations in HIV reverse transcriptase (RT) at position 145, specifically Met and Leu substitutions, confer resistance to antiretrovirals. These mutations reduce viral replication and enzyme efficiency, explaining their lower frequency in patients.

Area of Science:

  • Virology
  • Molecular Biology
  • Drug Resistance

Background:

  • Highly active antiretroviral therapy (HAART) has improved HIV management.
  • Monitoring drug resistance mutations in HIV reverse transcriptase (RT) is crucial for treatment efficacy.
  • Specific mutations in HIV RT are associated with resistance to antiretroviral drugs.

Purpose of the Study:

  • To investigate the impact of mutations at codons 145, 151, and 69 of the HIV-1 RT gene on drug resistance and viral replication.
  • To determine which amino acid substitutions at position 145 confer multidrug resistance.
  • To understand the mechanism behind the observed frequencies of specific mutations in HAART-experienced patients.

Main Methods:

  • Analysis of HIV RT gene mutations in 3,595 HAART-experienced patients.
  • Site-directed mutagenesis to introduce specific amino acid substitutions at position 145.
  • Assay of drug susceptibility and replication levels of recombinant HIV strains.
  • In vitro inhibition assays to assess the catalytic efficiency and drug resistance of mutated HIV RT enzymes.

Main Results:

  • Frequencies of mutations at codons 145, 151, and 69 were 0.22%, 2.36%, and 0.86%, respectively.
  • Only Met and Leu substitutions at position 145 of HIV-1 RT conferred multidrug resistance.
  • The Gln145Met recombinant strain showed lower replication levels and reduced catalytic efficiency, with significant resistance to zidovudine and efavirenz.
  • Other amino acid substitutions at position 145 did not confer multidrug resistance.

Conclusions:

  • Specific amino acid substitutions (Met, Leu) at position 145 in HIV-1 RT are critical for conferring multidrug resistance.
  • These resistance-associated mutations can decrease viral replication and enzyme activity, potentially by interfering with the nucleotide-binding pocket.
  • The reduced viral fitness associated with certain mutations at position 145 may explain their lower observed frequency compared to other resistance mutations.

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