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Thymidine Analogue Mutations with M184V Significantly Decrease Phenotypic Susceptibility of HIV-1 Subtype C Reverse
Hyeonah Byun1, Maria Antonia Papathanasopoulos1, Kim Steegen2,3
1HIV Pathogenesis Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.
Islatravir shows effectiveness against common HIV-1 subtype C nucleoside reverse transcriptase inhibitor resistance mutations. However, combinations involving M184V with thymidine analogue mutations may reduce susceptibility, impacting treatment strategies.
Area of Science:
- Virology
- Infectious Diseases
- Pharmacology
Background:
- Islatravir (ISL) is a novel nucleoside reverse transcriptase translocation inhibitor (NRTtI) with a unique mechanism of action.
- Limited data exist on ISL resistance, especially in non-B HIV-1 subtypes.
- Understanding resistance patterns is crucial for optimizing ISL's clinical utility.
Purpose of the Study:
- To evaluate the phenotypic resistance of prevalent nucleos(t)ide reverse transcriptase inhibitor (NRTI)-resistant mutations in HIV-1 subtype C to Islatravir (ISL).
- To assess the impact of single and combined NRTI resistance mutations on ISL susceptibility in HIV-1 subtype C.
Main Methods:
- Selected prevalent NRTI-resistant mutations from HIV-1 genotypic drug resistance testing databases.
- Introduced these mutations into HIV-1 subtype C-like pseudoviruses.
- Assessed ISL susceptibility using phenotypic resistance testing.
Main Results:
- Single NRTI resistance mutations showed low-level or no resistance to ISL.
- Combinations of M184V with thymidine analogue mutations (TAMs), especially TAM-2, reduced ISL susceptibility.
- Combinations of M184V with K65R did not significantly affect ISL susceptibility.
Conclusions:
- ISL is likely effective for patients failing tenofovir disoproxil fumarate (TDF)/lamivudine (3TC) or TDF/emtricitabine (FTC) regimens.
- ISL may be less effective for patients failing zidovudine (AZT) with 3TC or FTC regimens due to specific resistance mutation combinations.
- Further research is needed to fully elucidate ISL resistance profiles in diverse HIV-1 subtypes.
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