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Universal vaccination is the most effective strategy to control hepatitis B virus (HBV) infection. In Argentina, vaccination against HBV was incorporated in year 2000 for newborns and in 2003 for 11 years old children. However, there is a paucity of data about protection levels against HBV infection. The aim of this work was to determine the prevalence of seroprotective anti-HBs antibodies (aHBs) in Argentina. Serum samples negative for HBsAg and anti-HBc from 132 children born after year 2000 and 762 blood donors, older than 18 years, from five centers across the country, were analyzed for aHBs. Titers ¡Ý10 mIU/mL were observed in 74/132 children (56.1%) and 336/762 (44.1%) in blood donors. The median age for blood donors was 33.9 (23¨C43); from them, 210 (27.6%) were born after 1992 and, therefore, were catch-up by vaccine implementation at 11 years old age. Donors born in 1992 or before showed a significantly lower frequency of protection (32.2%) compared to donors born after 1992 (75.2%), p < 0.0001. In addition, significant differences were observed in the status of seroprotection between different participating centers (p = 0.024). Implementation of HBV vaccine in 2000 and 2003 implied an overall increase of the aHBs seroprotective rates, with a particularly adequate response in children vaccinated at 11 years old age. The observed results suggest that population born in 1992 or before is currently the most susceptible. Consequently, it would be advisable to become aware of the risk of transmission in this age group and to stress this population vaccination campaigns. Fil: Di Lello, Federico Alejandro. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Blejer, Jorgelina L.. Fundación Hemocentro; Argentina Fil: Alter, Adriana. Fundación Hemocentro; Argentina Fil: Bartoli, Sonia. Centro Regional de Hemoterapia Jujuy; Argentina Fil: Vargas, Fabiana Alejandra. Centro Regional de Hemoterapia de Mendoza; Argentina Fil: Ruiz, Rosángela. Hospital Regional Rio Grande; Argentina Fil: Galli, Claudio. Hospital Regional Rio Grande; Argentina Fil: Blanco, Sebastian. Universidad Nacional de Córdoba. Facultad de Medicina; Argentina. Fundación Banco Central de Sangre; Argentina Fil: Gallego, Sandra Veronica. Fundación Banco Central de Sangre; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina; Argentina Fil: Fernández, Roberto. Fundación Hemocentro; Argentina Fil: Martínez, Alfredo P.. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; Argentina Fil: Flichman, Diego Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina

BackgroundThe genetic diversity of persistent infectious agents, such as HHV-8, correlates closely with the migration of modern humans out of East Africa which makes them useful to trace human migrations. However, there is scarce data about the evolutionary history of HHV-8 particularly in multiethnic Latin American populations.ObjectivesThe aim of this study was to characterize the genetic diversity and the phylogeography of HHV-8 in two distant geographic regions of Argentina and to establish potential associations with the genetic ancestry of the population.Study designA total of 605 HIV-1 infected subjects, Kaposi’s Sarcoma (KS) patients and blood donors were recruited in the metropolitan (MET) and north-western regions of Argentina (NWA). After HHV-8 DNA detection, ORF-26 and ORF-K1 were analyzed for subtype assignment. Uniparental and biparental ancestry markers were evaluated in samples in which subtypes could be assigned. Phylogeographic analysis was performed in the ORF-K1 sequences from this study combined with 388 GenBank sequences.ResultsHHV-8 was detected in 24.8% of samples. ORF-K1 phylogenetic analyses showed that subtypes A (A1-A5), B1, C (C1-C3) and F were present in 46.9%, 6.25%, 43.75% and 3.1% of cases, respectively. Analyses of ORF-26 fragment revealed that 81.95% of strains were subtypes A/C followed by J, B2, R, and K. Among KS patients, subtype A/C was more commonly detected in MET whereas subtype J was the most frequent in NWA. Subtypes A/C was significantly associated with Native American maternal haplogroups (p=0.004), whereas subtype J was related to non-Native American haplogroups (pConclusionsThese results give evidence of the geographic circulation of HHV-8 in Argentina, provide new insights about its relationship with ancient and modern human migrations and identify the possible origins of this virus in Argentina.

Although the detection of HTLV antibodies became mandatory in Argentinean blood banks since 2005, there is no recommendation on how to perform the screening. As a consequence, there is a variable number of HTLV false positives depending on the kit used. The aim of the present study was to evaluate the performance of six commercial screening tests available currently for the initial diagnosis of HTLV-1/2 infection in South America. The positive panel included 14 HTLV-1 and 13 HTLV-2 samples confirmed by WB (HTLV-1/2 MP Diagnostics). The negative panel included 233 samples analysed with Architect (n=47), Diapro (n=46), MP (n=45), Murex (n=47) and Serodia (n=48), collected in 5 different institutions in a period of one up to 10 consecutive days. All of them were confirmed by n-PCR. The sensitivity for all HTLV diagnostic kits was 100.0%. The most specific test was Serodia (PA) (99,1%; 2/233), followed by the ELISAs: Celquest (98.3%, 4/233), Murex (97.8%; 5/233), MP and Architect (97.4%; 6/233), and Diapro (93,1%; 16/233). According to this data, 2 to 16 blood units out of 233 should have been discarded due to false positive results in a period of 10 days. This data must be considered when choosing the assays, not only to obtain an optimal efficiency on HTLV-1/2 diagnosis, to increase the number of potential blood units and to decrease the circulation of anxious individuals without a final result, but also to lower the overall cost-benefits of the diagnosis in the health care system.