Genetic variation of the lambdaA and lambdaC protein encoding genes of avian reoviruses.

Sequence and phylogenetic analysis of lambdaA and lambdaC protein encoding genes of 12 avian reoviruses is described. The sequence of lambdaA possesses a variable region (residues 19-51) located within a conserved hydrophilic region (residues 1-110) and a C(2)H(2) zinc-binding motif (residues 182-202). lambdaC 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 lambdaA encoding genes and lambdaA proteins are 92% and 98%, respectively, and those of lambdaC encoding genes and lambdaC proteins are 91% and 95%, respectively. Phylogenetic analysis of lambdaA and lambdaC 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.