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Previous studies have classified the env sequences of bovine leukemia virus (BLV) provirus from different locations worldwide into between two and four genetic groupings. These different studies gave unique names to the identified groups and no study has yet integrated all the available sequences. Thus, we hypothesized that many of the different groups previously identified actually correspond to a limited group of genotypes that are unevenly distributed worldwide. To examine this hypothesis, we sequenced the env gene from 28 BLV field strains and compared these sequences to 46 env sequences that represent all the genetic groupings already identified. By using phylogenetic analyses, we recovered six clades, or genotypes, that we have called genotypes 1, 2, 3, 4, 5 and 6. Genotypes 1-5 have counterparts among the sequence groupings identified previously. One env sequence did not cluster with any of the others and was highly divergent when compared with the six genotypes identified here. Thus, an extra genotype, which we named 7, may exist. Similarity comparisons were highly congruent with phylogenetic analyses. Furthermore, our analyses confirmed the existence of geographical clusters. INTRODUCTIONBovine leukemia virus (BLV) is a member of the family Retroviridae belonging to the genus Deltaretrovirus. This genus also includes Simian T-lymphotropic virus 1, 2, 3 and 5 (STLV-1, -2, -3 and -5) and Human T-lymphotropic virus 1, 2, 3 and 4 (HTLV-1, -2, -3 and -4). have not yet been associated with any pathology, likely due to their recent identification and to the low number of isolates. Therefore, BLV is considered a model of HTLV-1 and -2 . BLV is recognized as the aetiological agent of enzootic bovine leukosis, a disease that results in significant economic losses for the worldwide cattle industry. The most conspicuous clinical manifestation of bovine leukosis, which only develops in a small fraction of infected animals, is the clonal expansion and local accumulation of B cells that results in the development of lymphoid tumours (lymphosarcoma, LS) (Gillet et al., 2007). The majority of infections are not associated with any clinical signs (AL), and in approximately 30 % of infected cattle, the virus causes a persistent lymphocytosis (PL) (Burny et al., 1987;Mirsky et al., 1996).Analyses of the BLV envelope (env) gene of isolates collected in multiple geographical locations demonstrated significant sequence conservation (Camargos et al., 2002(Camargos et al., , 2007Coulston et al., 1990). Nevertheless, up to seven BLV genotypes can be identified by RFLP analysis (Asfaw et al., 2005;Coulston et al., 1990;Fechner et al., 1997;Kettmann et al., 1981;Licursi et al., 2002). Furthermore, the env sequences of the BLV provirus from different locations worldwide have previously been classified into between two and four genetic groupings (Camargos et al., 2002(Camargos et al., , 2007Felmer et al., 2005;Hemmatzadeh, 2007;Licursi et al., 2003;Mamoun et al., 1990;Monti et al., 2005;Zhao & Buehring, 2007), with similar results...

Here we present a system for adenovirus detection and genotyping based on PCR amplification and phylogenetic analysis of a conserved hexon gene fragment. The system was validated using 157 sequences (86 previously typed and 71 clinical samples) and correctly identified species and serotype in 100% and 84% of sequences, respectively. Known associations between specific serotypes and clinical syndromes are verified. Possible new associations are described to allow further independent testing.

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In order to investigate hepatitis C virus (HCV) persistence and replication in peripheral blood mononuclear cells (PBMC) from a group of haemophilic individuals, HCV production and release to PBMC culture supernatants (SNs) from HCV singly infected patients and HIV/HCV co-infected patients was studied. HCV RNA + SNs were found more frequently from HIV/HCV co-infected individuals (89?5 %) with poor reconstitution of their immune status than from singly HCV-infected patients (57 %) or from HIV/HCV co-infected individuals with a good response to highly active anti-retroviral therapy (50 %). The presence of the HCV genome in culture SNs was associated with lower CD4 + T-cell counts and with a more severe clinical picture of HIV infection. In spite of prolonged negative HCV viraemia, PBMC from HIV/HCV co-infected patients released the HCV genome after culture. HCV permissive PBMC allowed generation of HCV productive B cell lines with continuous HCV replication. These findings add further weight to the involvement of PBMCs in persistence of HCV infection and emphasize the role of B lymphocytes as HCV reservoirs.