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Mutations conferring drug resistance affect eukaryotic expression of HIV type 1 reverse transcriptase
Maria G Isaguliants1, Sergey V Belikov, Elizaveta S Starodubova
1Ivanovsky Institute of Virology, 123098 Moscow, Russia. maria.isaguliants@smi.ki.se
AIDS Research and Human Retroviruses
|March 17, 2004
Summary
Drug resistance mutations in HIV reverse transcriptase (RT) reduce viral fitness by decreasing RT expression. This is due to increased proteolytic instability, impacting HIV replication capacity.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Drug resistance mutations in HIV reverse transcriptase (RT) are crucial for treatment failure.
- These mutations often lead to reduced viral replication capacity (fitness), but the underlying mechanisms are unclear.
Purpose of the Study:
- To investigate how drug-resistance mutations affect the expression levels of HIV RT.
- To elucidate the molecular basis for reduced viral fitness in drug-resistant HIV strains.
Main Methods:
- Genes encoding AZT-resistant RT mutants were expressed in eukaryotic cells.
- Expression levels were assessed using Western blotting, immunofluorescent staining, and sandwich ELISA in Xenopus laevis oocytes.
- Proteolytic stability was evaluated through pulse-chase experiments.
Main Results:
- RT expression levels decreased with an increasing number of drug-resistance mutations.
- Poor expression of drug-resistant RT (DR-RT) was linked to proteolytic instability.
- Proteolytic instability was associated with predicted cleavage sites near resistance mutations.
Conclusions:
- Accumulation of drug-resistance mutations induces proteolytic instability in HIV-1 RT.
- This instability reduces eukaryotic expression levels of RT.
- Lower RT levels may contribute to the impaired replication fitness of drug-resistant HIV-1 strains.