Primary Antiretroviral Drug Resistance among HIV Type 1-Infected Individuals in Brazil

Abstract

Infection with drug-resistant human immunodeficiency virus type 1 (HIV-1) has been documented in all countries that have surveyed for it and may result in an unfavorable response to therapy. The prevalence and characteristics of individuals with transmitted resistance to antiretroviral drugs have been scarcely described in Brazil. We performed antiretroviral resistance testing prior to initiation of therapy in 400 subjects enrolled from 20 centers in 13 Brazilian cities between March and September 2007. Genotyping was conducted using PCR-amplified HIV pol products by automated sequencing, and genotype interpretation was done according to the IAS-USA consensus. Of 400 eligible participants, 387 (95.8%) were successfully tested. Seven percent of antiretroviral-naive patients carried viruses with one or more major mutation associated with drug resistance. The prevalence of these mutations was 1.0% for protease inhibitors, 4.4% for nonnucleoside reverse transcriptase inhibitors, and 1.3% for nucleoside reverse transcriptase inhibitors. The frequency of multidrug resistance among the resistant strains was 13.6%. Among subjects infected with drug-resistant virus, the majority were infected with subtype B viruses (91%). Subjects from the city of São Paulo had higher transmitted resistance mutations compared to the rest of the country. Reporting a partner taking antiretroviral medications was associated with a higher chance of harboring HIV variants with major drug resistance mutations [odds ratio = 2.57 (95% confidence interval, 1.07-6.16); p = 0.014]. Resistance testing in drug-naive individuals identified 7% of subjects with mutations associated with reduced susceptibility to antiretroviral drugs. Continued surveillance of drug-resistant HIV-1 in Brazil is warranted when guidelines for HIV prophylaxis and treatment are updated. Resistance testing among drug-naive patients prior to treatment initiation should be considered, mainly directed at subjects whose partners are already on antiretroviral therapy.

Genetic diversity and primary resistance among HIV-1-positive patients from Maringá, Paraná, Brazil

“…The prevalence of ARV-transmitted resistance observed in this study (4.2%) was comparable to that reported by SPRINZ et al 34 , who investigated 387 treatment-naïve patients from 13 Brazilian cities (Ribeirão Preto, Santo André, Santos, Nova Iguaçu, Rio de Janeiro, Belo Horizonte, GASPARETO …”

“…Subtype C was detected in 25%; other studies analyzing samples from patients of the southern region have observed similarly high prevalences of subtype C 7,8,24,34 . For instance, a study conducted in Santa Catarina (n = 80) reported a high prevalence of subtype C (48.75%), which increased to 71.25% when the recombinant viruses containing subtype C-related sequences were included in the analysis 24 .…”

Heterosexual transmission of human immunodeficiency virus type 1 subtype C in southern Brazil

“…1). [2][3][4][5] However in the Southern region, a distinct profile is observed. Currently, depending on the state, 27-79% of HIV infections are caused by HIV-1C, 23-45% by HIV-1B, 3-29% by CRF31 BC and other BC recombinants, and HIV-1F and its recombinants account for up to 10% of infections.…”

Identification of Novel Resistance-Related Polymorphisms in HIV-1 Subtype C RT Connection and RNase H Domains from Patients Under Virological Failure in Brazil

“…2,3 In Brazil, the major circulating HIV-1 subtype is B (HIV-1B), yet other subtypes such as A1, C, D, F1, BF1, and BC recombinants have also been found. [4][5][6][7] The southern region of Brazil is unique, with an endemicity of HIV-1 subtype C (HIV-1C). Several studies have reported an increase in HIV-1C prevalence in that region.…”