A genotypic analysis of patients receiving Zidovudine with either Lamivudine, Didanosine or Zalcitabine dual therapy using the LiPA point mutation assay to detect genotypic variation at codons 41, 69, 70, 74, 184 and 215

Background: The Murex-Innogenetics LiPA HIV-1 RT assay can be used to ident ify the presence of mutations of the reverse transcriptase gene at codons 4 1, 69, 70, 74, 184 and 215 of HIV-1, which have been shown to confer resist ance to the nucleoside analogs Zidovudine (ZDV), Lamivudine (3TC), Didanosi ne (ddI) and Zalcitabine (ddC). The M184V mutation of the reverse transcrip tase gene of HIV-1 has been associated with resistance to 3TC, ddC and ddI. This mutation has also been observed in patients receiving ZDV + ddC and Z DV + ddI. We used LiPA HIV-I RT assay to identify the presence of either co nsensus methionine 184 or the mutant valine 184 with three groups of patien ts who were: treated with ZDV/3TC, ZDV/ddI or ZDV/ddC combination therapy. Objectives: The aim of our study was to determine the viral genotype of pat ients who were considered to be failing therapy, by two ways: using sequenc ing and LiPA assays. In particular we were interested in establishing a pos sible correlation between these methods. Study design: The study group cons isted of a consecutive series of 33 patients with a treatment failure, 18 o f whom received ZDV + 3TC therapy, seven received ZDV + ddI and eight recei ved ZDV + ddC therapy. We also examined a small cohort of seven seroconvert ers, Results: The M184V mutation was observed in 47.0% of patients receivin g ZDV + 3TC combination therapy but was not observed in either patient grou p receiving either ddI or ddC as co-therapy with ZDV. There was no evidence of the L74V mutation in our study group in either the ZDV/ddI or ZDV/ddC c ombination therapy group. We found the frequency of the K70R mutation to be higher in patients treated with ZDV/ddI (P = 0.033) or ZDV/ddC (P = 0.3) w hen compared with patients treated with ZDV/3TC. Conclusion: The LiPA assay allowed for the rapid detection of wild type and amino acid variations at key positions conferring resistance to the most used antiviral RT inhibitor s. This represented a rapid, quite sensitive, and simple genotyping test. F ur these reasons the LiPA assay proved to be useful in studying genetic res istance in large screenings, when key RT mutations could be useful in guidi ng an effective HIV-1 suppressing regimen. (C) 2000 Elsevier Science B.V. A ll rights reserved.