HIV-1 GENETIC DIVERSITY IS A MAJOR OBSTACLE FOR ANTIRETROVIRAL-DRUG RESISTANCE HYBRIDIZATION-BASED ASSAYS

KIJAK GH; CAROBENE M; RUBIO A; SALOMON H

Buenos Aires, Argentina

Conferencia; 1st IAS Conference on HIV Pathogenesis and Treatment; 2001

International AIDS Society

Background: The Line Probe Assay (LiPA) is one of the methods approved for the study of antiretroviral (ARV) drug-resistance in Argentina. In general, commercial genotyping assays have been designed based on the most prevalent motifs in the US and Europe, belonging to the B subtype, but little is known about their performance on non-B subtype samples. Objective: The aim of the present study was to analyze the relation between the genetic diversity of HIV-1 circulating in Argentina and the low reactivity at codon 74 in the LiPA test for samples from HIV-1 infected individuals from Argentina. Materials and Methods: Samples from 103 HIV-1 infected individuals from Buenos Aires (Argentina) were studied. Mutations in HIV-1 RT were analyzed using INNO-LiPA HIV-1 RT (INNOGENETICS, Belgium) and automatic sequencing (Visible Genetics, Canada). Phylogenetic analyses were performed with PHYLIP package. Intersubtype recombinant forms were assessed with Simplot and Blast subtyping. Results: By using LiPA results for codons 41, 69, 70, 184 and 215 were obtained in 81-97% of the samples, depending on the codon. However, no reaction at codon 74 was observed in 36/103 (35.0%) samples. By sequencing, a silent mutation at codon 72 of RT (AGA->AGG) was detected in 35/36 (97.2%) of the non-reacting samples. The presence of this mutation was significantly correlated with the absence of reaction at codon 74 in LiPA. In a phylogenetic analysis of 93 of the samples, the lack of reactivity at codon 74 and the presence of the polymorphism at codon 72 were significantly associated with F1/B subtype recombinant HIV-1 forms previously described in the region. Conclusions: A polymorphism at codon 72 of HIV-1 RT which is associated with highly prevalent F1/B subtype recombinant forms circulating in Argentina prevents the hybridization with probes for codon 74 in the LiPA test, demonstrating that the genetic diversity of HIV-1 is a major obstacle for ARV-drug resistance hybridization-based assays.