Determinants of HIV-1 mother-to-child transmission in Southern Brazil

Abstract

Different human immunodeficiency virus type 1 (HIV-1) subtypes may have distinct biological, immunological and pathogenic properties. Efficiency of mother-to-child transmission (MTCT) may be among those properties, but few and controversial results have been described so far. In this study, 102 children born from HIV-1-infected mothers between 1998 and 2004 in the city of Rio Grande, Brazil were analyzed for potential risk factors associated with MTCT. That geographic region is characterized by a high proportion of subtype C-infected subjects, and it allowed comparison between subtypes B and C and their influence on MTCT. The analysis also included clinical, obstetric and immunological parameters. Multivariate regression analyses were conducted to evaluate the influence of the parameters on MTCT, and prevalence ratios (PR) and 95% confidence intervals (CI95) were also calculated. A surprisingly high prevalence of subtype C of over 70% was found. Only the HIV viral load and the use of ACTG 076 protocol were predictive of MTCT. HIV subtype and CD4 T-cell counts were not associated with increased risk of transmission. Although a clear expansion of subtype C is evident in southern Brazil, it does not seem to correlate with increased risk of vertical transmission.

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

“…Several studies have reported an increase in HIV-1C prevalence in that region. [8][9][10][11][12][13][14][15][16] In the city of Rio Grande, one of the foci of this study, such an increase is clearly evident: from 22% in 2002 to 56% in 2010. 16,17 The introduction of highly active antiretroviral therapy (HAART) in HIV-infected patients is associated with a marked reduction in morbidity and mortality.…”

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

“…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. [6][7][8][9][10][11][12][13][14][15][16] Recent studies suggest that the HIV-1 epidemics in Brazil has initiated with multiple introductions of HIV-1B during the 60s or 70s 17,18 in the largest cities of Southeast, and then disseminated throughout the country. HIV-1F and C had a monophyletic entry in the country, the former in the Southeast and the latter in the South, approximately 10-15 years after HIV-1B.…”

Diversidade genética do vírus da imunodeficiência humana tipo 1 (HIV-1) em mulheres infectadas de uma cidade do nordeste do Brasil

“…Outros fatores relacionados à mãe, como a carga viral plasmática elevada, a diversidade do vírus circulante e a resistência aos antirretrovirais (ARV) representam riscos adicionais responsáveis por 30 a 35% dos casos de transmissão vertical 4 . No entanto, há relatos com resultados controversos sobre o papel dos subtipos e recombinantes nesta forma de transmissão viral [5][6][7] . O HIV-1 tem um genoma relativamente pequeno, que mede aproximadamente 9 kilobytes (Kb) de comprimento ocupados em grande parte pelos três genes estruturais: gag (grupo antígeno), pol (polimerase) e env (envelope), que são delimitados por duas regiões contendo sequências repetitivas, denominadas LTR (longas regiões terminais repetidas) 8 .…”