Application of HIV-1 genotypic-resistance testing prevents the evolution of further resistance mutations in heavily pretreated patients

Genetic Consequences of Antiviral Therapy on HIV-1

A variety of enzyme inhibitors have been developed in combating HIV-1, however the fast evolutionary rate of this virus commonly leads to the emergence of resistance mutations that finally allows the mutant virus to survive. This review explores the main genetic consequences of HIV-1 molecular evolution during antiviral therapies, including the viral genetic diversity and molecular adaptation. The role of recombination in the generation of drug resistance is also analyzed. Besides the investigation and discussion of published works, an evolutionary analysis of protease-coding genes collected from patients before and after treatment with different protease inhibitors was included to validate previous studies. Finally, the review discusses the importance of considering genetic consequences of antiviral therapies in models of HIV-1 evolution that could improve current genotypic resistance testing and treatments design.

Epidemiology of antiretroviral multiclass resistance

Given the recent evolution of therapeutic trends, the frequency and determinants of multiclass-resistant HIV infection in the modern combination highly active antiretroviral therapy (HAART) era are less well understood. In this study, the authors characterize the epidemiology of antiretroviral multiclass resistance among HAART-naïve patients enrolled in a province-wide HAART distribution program in British Columbia, Canada. HAART and resistance testing are free to eligible individuals in British Columbia. This study was based on patients who initiated naïve on HAART and were followed during January 1, 2000-June 30, 2007. Explanatory logistic and survival models were built to identify those factors most influential in the emergence of multiclass resistance. Among the 1,820 individuals in our study, 833 (46%) were tested for antiretroviral resistance at least once during their follow-up. Multiclass resistance was observed in 142 individuals (n = 833; 17%) during a median follow-up of 14 months (interquartile range, 3-34 months) (incidence rate, 0.8 cases/1,000 person-months). The authors found that initial nonnucleoside reverse transcriptase inhibitor-based HAART was the main determinant of multiclass resistance. Given that these inhibitors are still widely used, priority should be given to make resistance testing and viral load monitoring a standard part of human immunodeficiency virus care to maximize the long-term efficacy and efficiency of HAART.

Mutagenically separated PCR assay for rapid detection of M41L and K70R zidovudine resistance mutations in CRF01_AE (subtype E) human immunodeficiency virus type 1

A rapid zidovudine (ZDV) resistance genotypic assay was developed based on the mutagenically separated PCR (MS-PCR) technique to detect two ZDV-resistant mutations, M41L and K70R in CRF01_AE (subtype E). Endpoint dilution analysis revealed that the newly constructed MS-PCR assay could successfully detect three to nine copies of human immunodeficiency virus type 1 template RNA. The test against wild-type and mutant template mixtures in different ratios demonstrated that the assay could detect 10% minor population, at least. Fifty-one subtype E clinical samples were analyzed by the newly constructed MS-PCR assay and direct nucleotide sequencing. The concordance of the two assays was 92 and 100% in codons 41 and 70, respectively. The MS-PCR assay is a rapid, simple, and inexpensive assay that is highly sensitive in detecting mutant targets, including minor populations. Thus, it could be used as a powerful tool for epidemiological surveillance of drug-resistant mutations in developing countries.