The aim of this study was to determine the rate and risk factors of HIV-1 mother-to-child transmission (MTCT), the timing of transmission and the transmitted subtype in a population where subtypes B and C co-circulate. One hundred and forty-four babies born to HIV-1-infected mothers were studied. Subtype and timing of transmission were determined by a nested polymerase chain reaction of the gp41 gene. Seven children were infected (4.9%): four were infected intrautero and one intrapartum. The higher frequency of intrautero transmission was statistically significant (P = 0.001). Use of antiretrovirals (ARVs) in the three stages of gestation was a protective risk factor for MTCT (PR = 0.42; CI: 0.21-0.83; P = 0.013). A higher HIV viral load at delivery was the only independent risk factor for MTCT. Early and universal access to ARVs during pregnancy are the most important measures to decrease vertical HIV-1 transmission even in areas where HIV clade distribution differs.

Major resistance-conferring mutations to NNRTI were detected in 10% of RT connection domain viral sequences from treatment-naïve subjects. We showed for the first time that the presence of specific polymorphisms can constrain the acquisition of definite resistance mutations in the connection and RNase H subdomains of HIV-1 RT.

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Objective: This study estimated CMV molecular prevalence in placental biopsies as well as in umbilical blood cord and its correlation with infection of pregnant women and their newborns to determinate vertical transmission risks. Design: A cross-sectional study Setting: Obstetric Center of the University Hospital in Rio Grande, Brazil Population: 496 pregnant women and their newborns Methods: Biopsies were collected from peripheral and central portions of each placenta, separated on fetal and maternal interfaces, matched with cord blood, totaling 1488 samples. PCR technique and sequencing were used to investigate the prevalence. Main Outcome Measures: Bivariate and multivariate analysis were performed to determinate sociodemographic, clinical and gynecological data associated to CMV vertical transmission. Results: CMV DNA was found in 5.2% of placental maternal interface and 5.4% of fetal interface with a positive result for CMV in 3.6% in cord blood. In more than 90% of the cases, there was no match between positive CMV DNA cord blood and positive placentas, indicating vertical transmission ascending from genital tract. The income factor (less than 1 minimum wage) was significantly associated with prevalence of CMV in placentas (p = 0.03). In cord blood samples, non-white skin color and early age at the onset of sexual intercourse were risk factors associated with the infection (p = 0.04). Conclusions: The occurrence of CMV DNA found in cord blood suggests the pattern observed appears to be ascending from genital tract of asymptomatic mothers. Economical and environmental factors present a negative impact on fetal-maternal transmission of cytomegalovirus.