Genetic variation of the λA and λC protein encoding genes of avian reoviruses

Sequence and phylogenetic analysis of λA and λC protein encoding genes of 12 avian reoviruses is described. The sequence of λA possesses a variable region (residues 19-51) located within a conserved hydrophilic region (residues 1-110) and a C2H2 zinc-binding motif (residues 182-202). λC shows the two conserved K residues at positions 169 and 188 indicative of guanylyltransferase activity, an ATP/GTP-binding site motif A (residues 379-386), and a conserved S-adenosyl-l-methionine-binding motif (residues 822-830). Pairwise sequence comparisons show that the mean sequence identities of λA encoding genes and λA proteins are 92% and 98%, respectively, and those of λC encoding genes and λC proteins are 91% and 95%, respectively. Phylogenetic analysis of λA and λC encoding genes reveals that both encoding genes have diverged into three distinct lineages, respectively, and that there is no correlation between lineages and viral serotypes or pathotypes. Also, reassortment of gene segments L1 and L3 has been observed between viruses.