Genomic heterogeneity in the pol region of ovine lentiviruses obtained from bronchoalveolar cells of infected sheep from France

In order to determine the genomic heterogeneity of ovine lentiviruses, we analysed eight isolates from naturally infected sheep from one geographical region of France. A 475 nt fragment in the region of the pol gene coding for reverse transcriptase was amplified by RT-PCR from RNA directly extracted from uncultured bronchoalveolar lavage cells. The resulting PCR fragments were analysed by restriction enzyme digestion, cloned in a TA vector and sequenced. Restriction enzyme analysis showed distinct patterns from the eight isolates, and sequencing showed them to be closely related in both nucleotide (2.3-8.1% variation) and deduced amino acid (0-6.2% variation) sequences. Their amino acid sequences differed from that of visna-maedi virus complete viral genome sequence K1514 by 12.5-15.3%, but from that of caprine arthritis encephalitis virus (CAEV) viral genome sequence Co by only 4.2-6.9%. Phylogenetic analysis showed that the French isolates form a group related to CAEV Co and distant from previously reported ovine lentivirus sequences from different origins.