Signature patterns in region V4 of small ruminant lentivirus surface protein in sheep and goats.

The env gene in Small Ruminant Lentiviruses (SRLV) encodes the surface glycoprotein (SU) that divides into conserved (C1-C4) and variable regions (V1-V5). SRLV region V4 has been found to be homologous to the V3 region of human lentivirus (HIV). HIV V3 is responsible for tropism and the development of nervous clinical patterns when there is a tendency to conserve amino acids in specific "signature pattern" positions. The goal of this study was to identify signature patterns in the V4 region of the SU, which is encoded by the SRLV env gene. Secondarily, to understand how these signature patterns are associated with different clinical status in naturally infected sheep and goats. Starting with 244 samples from seropositive animals from nine Mexican states, we amplified the V4 region using nested PCR and obtained 49 SRLV sequences from peripheral blood leukocytes. Based on phylogenetic analysis results, we identified three groups: asymptomatic genotypes A (Ssx GA) and B (Ssx GB), as well as animals with arthritic presentation, genotype B (A GB). Similarity levels between group sequences ranged from 67.9%-86.7%, with a genetic diversity ranging from 12.7%-29.5% and a dN / dS ratio that indicated negative selection. Analyses using Vespa and Entropy programs identified four residues at positions 54, 78, 79 and 82 in SU region V4 as possible signature patterns, although with variable statistical significance. However, position 54 residues "N" (p = 0.017), "T" (p = 0.001) and "G" (p = 0.024) in groups A GB, Ssx GA and Ssx GB respectively, best characterized the signature patterns. The results obtained identified a signature pattern related to different genotypes and clinical status by SRLV in sheep and goats.