Abstract

Primary resistance in the RT connection and RNase H domains in different HIV-1 subtypes

A.F. Santos¹, C.P. Muniz¹, L.R. Goés², J. Silveira³, A.M.B. Martinez³, U. Tupinambás⁴, D. Greco⁴, M.A. Soares<sup>2,5

1</sup>Universidade Federal do Rio de Janeiro, Departamento de Genética, Rio de Janeiro, Brazil, ²Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, ³Fundação Universitaria do Rio Grande, Rio Grande, Brazil, ⁴Universidade Federal de Minas Gerais, Belo Horizonte, Brazil, ⁵Instituto Nacional de Câncer, Rio de Janeiro, Brazil

Background: Mutations in HIV-1 RT C-terminal domains, connection and RNase H, have been shown to play an important role in resistance to RT inhibitors. In Brazil, the rate of primary resistance in PR and RT polymerase domain is below 10%. Here we evaluate the primary resistance in connection and RNase H domains and compared the presence of primary mutations in diverse HIV-1 subtypes.
Methods: One hundred twenty-nine treatment-naïve patients recently diagnosed for HIV-1 were screened in 1,454 naïve-treatment isolates of five HIV-1 subtypes obtained from the infection (2007-8) in Southern Brazil had their viral RNA isolated from plasma and retrotranscribed. Nested PCR amplified the genomic regions corresponding to RT connection and RNase H. Products were sequenced and subtyped by phylogenetic analysis. All drug resistance mutations (DRM) considered here had their phenotypic role in resistance determined in recent studies: N348I, A360V, T369V, A371V, I506L, Q509L and Q547K. DRM Stanford Database: subtype A (138), B (442), C (495), CRF01_AE (166) and CRF02_AG (213). Chi-square tests were conducted to compare the frequency of each DRM across subtypes with that of subtype B.
Results: Of 129 isolates, nine (6.9%) presented at least one RT C-terminal mutation. The mutation A371V was found in 4.5% of patients, followed by T369V (2.3%), Q547K (1.9%) and I506L (0.9%). The mutation A371V was shown as a genetic signature of subtype A, CRF01_AE and CRF02_AG. Interestingly, T369Vwas present in 20% of CRF02_AG isolates, while its presence in other subtypes was below 6% (p< 0.001), and is considered a major DRM to nevirapine in subtype B.
Conclusions: This study is the first to detect DRM in HIV-1 RT connection and RNase H regions from naïve-treatment patients. Some DRM in these domains presented distinct proportion in different HIV-1 subtypes. We recommend the inclusion of these mutations in resistance surveillance protocols.