Molecular characterization of chicken infectious anemia virus circulating in Argentina during 2007.

Chicken infectious anemia virus (CAV) is a worldwide-distributed infectious agent that affects commercial poultry. Although this agent was first detected in Argentina in 1994, no further studies on CAV in this country were reported after that. The recent increased occurrence of clinical cases of immunosuppression that could be caused by CAV has prompted this study. Our results confirmed that CAV is still circulating in commercial flocks in Argentina. Phylogenetic analysis focusing on the VP1 nucleotide sequence showed that all Argentinean isolates grouped together in a cluster, sharing a high similarity (> 97%) with genotype B reference strains. However, Argentinean isolates were distantly related to other strains commonly used for vaccination in this country, such as Del-Ros and Cux-1. Sequence analysis of predicted VP1 peptides showed that most of the Argentinean isolates have a glutamine residue at positions 139 and 144, suggesting that these isolates might have a reduced spread in cell culture compared with Cux-1. In addition, a particular amino acid substitution at position 290 is present in all studied Argentinean isolates, as well as in several VP1 sequences from Malaysia, Australia, and Japan isolates. Our results indicate that it is possible to typify CAV strains by comparison of VPI nucleotide sequences alone because the same tree topology was obtained when using the whole genome sequence. The molecular analysis of native strains sheds light into the epidemiology of CAV in Argentinean flocks. In addition, this analysis could be considered in future control strategies focused not only on breeders but on broilers and layer flocks.