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Session 124 Poster Abstracts
Viral Pathogenesis in Mothers and Children
Tuesday, 1:30 - 3:30 pm
Poster Hall


903
Viral Load but Not HIV-1 Subtype C Infection Is Associated with in utero Mother-to-child Transmission in Brazil
M G Morgado*1, V G Veloso1, K A Nielsen2, F I Bastos1, R Lorete1, D L C Rufino dos Santos1, J H Pilotto3, E C Joao4, B Grinsztejn1, B R Santos5, R Kreitchmann6, R Fonseca7, and Y Bryson2
1Hosp. Cruz Fndn., Rio de Janeiro, Brazil; 2Univ. of California, Los Angeles, USA; 3Oswaldo Cruz Fndn., Hosp. Geral de Nova Iguaçú, Rio de Janeiro, Brazil; 4Hosp. dos Servidores do Estado, RJ, BR; 5Hosp. Conceição, PA, RS; 6Santa Casa, PA, RS; and 7Hosp. Fêmina, PA, RS

Background: South and southeastern regions of Brazil have different and contrasting HIV-1 epidemic dynamics, as well as different genetic subtype distributions. B and F are the predominant subtypes in southeastern Brazil, while subtype C is the prevailing subtype in the south. In the present study we evaluated HIV-1 subtype diversity, viral load and the CD4 counts in a population-based sample of HIV-positive women diagnosed during the peripartum period and their potential influence on in utero transmission.

Methods: HIV-1 status was evaluated in roughly 6000 women screened during the peripartum by a rapid HIV test (Determine 1/2). HIV-1-positive women were further confirmed by HIV EIA/ WB. Women and babies received standard of care prevention and/or treatment. Viral load was determined for the positive mothers in the peripartum period (NASBA, NucliSense, Biomerieux). CD4 counts were assessed by flow cytometry (XL-MCL Beckman/Coulter) using CD3/CD4/CD8 TriTest monoclonal antibodies (Beckton Dickinson). HIV-exposed infants had HIV DNA PCR (Roche) performed at birth. HIV-1 subtypes were determined for the mother blood samples based on the envHMA.

Results: Of 49 HIV-1-positive women from Rio de Janeiro (southeastern Brazil), 48 had their HIV-1 env subtype successfully determined by HMA; and of 98 women from Porto Alegre (south Brazil), 72 had their HIV-1 env subtypes successfully determined by HMA. The distribution of HIV-1 subtypes were, respectively, 85.5% B, 2%C , and 12.5% F for Rio de Janeiro; and 32% B, 65% C, and 3% F for Porto Alegre. Double B/C infection was found in 1 woman from Porto Alegre. Overall, 7 cases (4.8%) of HIV-1 intrauterine transmission were observed, with similar rates for women from Rio de Janeiro (6.1%) and Porto Alegre (4.1%). Viral load (p < 0.02) but not CD4 counts in the peripartum (Mann-Whitney Test) or HIV-1 subtype infection was associated with intrauterine transmission.

Conclusions:  In spite of  the high frequency of subtype C infections among pregnant women from Porto Alegre (65%), as compared with women from Rio de Janeiro, where subtype B was most prevalent,  no differences were found in rates of in utero transmission according to viral subtype. Further multicenter studies should be implemented, in order to increase statistical power and permit multivariate analyses.

Keywords: HIV-1 subtypes; vertical transmission; viral load