Vírus da leucose enzoótica bovina: filogenia e regulação gênica de LTR e POL em amostras brasileiras

Abstract

This work presents the results of the inquiry of two regions of the genoma of BLV virus Bovine Leukemia Virus, in Brazilian samples. The samples of bovine DNA, of BLV infected animais, belong to the bank of DNA of the Retrolab/EV/UFMG, deriving of four different localities in Brazil. Three PCRs had been developed: one was projected to amplify the constituent gene of the bovine B-actina and developed to have Access the quality of the DNAs. The second PCR was used in the amplification of na 582bp fragment inside the promoter region of the BLV, 5LTR, and the third PCR looked for to amplify na 783bp fragment within the terminal portion of the pol gene, correspondent to the intergrase codifyng region. The results of amplifications, its importance, sequences and phylogenetic analyses are presented and argued. Both PCRs designed to amplify fragments from the BLV genoma had reached the basic objective to generate the proposed products. Twenty two sequences from the 5LTR and tem sequences from pol region had been gotten. The phylogenetic analysis of the 5LTR pointed with respect to one high degree of conservation, and the construction of an phylogenetic tree allowed the characterization of Five groupings. However, hás not been possible to associate these groupings with the Brazilian regions of origino f the DNAs. In relation to the country of origin of the sequenced viruses, this tree suggests the formation of a grouping Brazil Argentina, a North American grouping with only one sample, FLK derived, a Japan Belgium Brazil grouping, a Brazil-only grouping and a Brazil Austrália grouping. Na restriction fragment lenght polymorphism RFLP in silico analyse of these fragments was executed, whose result corroborates in part the tree findings and suggests the formation of a South American macro - grouping, agglutinanting the Argentina sample and all Brazilian samples, but no one sample of other parto f the world. Moreover, the comparison of the 22 Brazilian samples indicated the presence of a more changeable region in a segment of 88bp, coincident with the DAS, downstream activator sequences, described by Kiss-Toth and Unk in 1994. The interaction of this finding with the viral transcription activity and the patogeny is argued. For the pol region, an phylogenetic tree was generated, showing consistent values of bootstrap. However, the small number of DNAs sequenced, as well as the available in the world-wide GenBank database for this region, did not allow the interference of consistent groupings. Was distinguished the existence of a more variable region in the terminal extremity from this sequences, that presented important amino acid changes in some samples.