BackgroundAs the most frequent pathway of vertical transmission of HTLV-1 is breast-feeding, and considering the higher prevalence in women, it is very important to perform screening examinations for anti-HTLV-1 antibodies as part of routine prenatal care. So far, no studies of HTLV-1 seroprevalence in pregnant women in the Southern region of Bahia, Brazil, have been described.MethodsPregnant women were selected at the two regional reference centers for health care from Southern Bahia. A total of 2766 pregnant women attending the antenatal unit between November 2008 and May 2010 have been analyzed. An extra blood sample was drawn during their routine antenatal testing. A standardized questionnaire was applied and all positive plasma samples were tested by ELISA and were confirmed by Western Blot and PCR. Besides that, positive women were contacted and visited. The family members that were present during the visit were asked to be serologically screened to the virus. A prospective study was also carried out and newborns were followed up to two years for evaluation of vertical transmission.ResultsHTLV prevalence was 1.05% (CI 95%: 0.70-1.50). There was no association of HTLV-1 infection with age, education, income and ethnic differences. The association with marital status was borderline (OR = 7.99; 95% CI 1.07-59.3; p = 0.042). In addition, 43 family members of the HTLV-1 seropositive women have been analyzed and specific reactivity was observed in 32.56%, including two children from previous pregnancy.Conclusion: It is very important to emphasize that the lack of HTLV-1 screening in pregnant women can promote HTLV transmission especially in endemic areas. HTLV screening in this vulnerable population and the promotion of bottle-feeding for children of seropositive mothers could be important cost-effective methods to limit the vertical transmission. Besides that, our data reinforce the need to establish strategies of active surveillance in household and family contacts as important epidemiological surveillance actions for the early detection of virus infection and the prevention of transmission by sexual or and parenteral contact.

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The human immunodeficiency virus type 1 (HIV-1), the etiological agent of the acquired immunodeficiency syndrome (AIDS), shows a variety of biological properties, which may constitute an obstacle to development of effective vaccines or antiretroviral therapy. To characterize Brazilian strains of HIV-1, we studied 24 viruses isolated from blood samples of HIV-1-positive patients from different regions of the country. To examine the cell tropism and the virus ability to form syncytia, primary macrophages and the CD4 1 T cell line MT-2 were infected with these viruses. We found that 22 isolates replicated well in macrophages (macrophage-tropic isolates), 2 infected only MT-2 cells (T cell line tropic variants), while 6 of them grew in both cells. We found 8 syncytium-inducing (SI) and 16 non-SI (NSI) isolates. Continuous cultures of 18 isolates were established in the CCR51 /CXCR4 1 cell line PM-1, and SI/NSI features of these viruses were confirmed by cell fusion assay with uninfected CD4 1 T cell lines (PM-1, MT-2, H9, and SUP-T1). The coreceptor usage of 18 isolates was investigated by infecting U87 cells transfected with CD4 and chemokine receptors, and we found that 11 isolates infected only CCR5 1 cells, 3 only CXCR4 1 cells, whereas 4 used both coreceptors. We also observed that X4 isolates were more sensitive to neutralization by dextran sulfate than R5 or R5X4 viruses. Our findings show that the Brazilian isolates are phenotypically similar to those prevalent in other regions, which could mean that therapeutic strategies based on HIV-1 phenotypic properties would be efficient in Brazil, as in other countries. 1241