Characterization of new Small Ruminant Lentivirus subtype B3 suggests animal trade within the Mediterranean Basin.

Small Ruminant Lentiviruses (SRLV) represent a group of viruses infecting sheep and goats worldwide. Despite the high heterogeneity of genotype A strains which cluster into as many as 10 subtypes, the genotype B was believed to be less complex and has so far been subdivided into only 2 subtypes. Here we describe two novel full-length proviral sequences isolated from Sarda sheep in two Italian regions. Genome sequence as well as the main linear epitopes clearly grouped this cluster into B genotype. However, due to long-lasting segregation of this sheep breed, the genetic distances clearly above 15% in respect to B1 and B2 subtypes, suggest the designation of a novel subtype B3. Moreover the close relationship with gag sequence obtained from a Turkish sheep adds new evidence to historical data suggesting an anthropochorous dissemination of hosts (small ruminants) and their pathogens (SRLV) during the Mediterranean colonization from Middle East.