3.3 Specific amino acid mutations in the NS and VP proteins of Vietnamese CPV-2c
Analysis of the deduced amino acid sequences of the NS1/NS2 genes revealed that all the Vietnamese CPV-2c strains presented the Ile60Val, Tyr544Phe, Glu545Val, and Leu630Pro mutations that were similar to the residues in the Italian CPV-2c (MF510157) and Chinese CPV-2a (KR002800) strains, but were not observed in the Vietnamese CPV-2a (HCM16) strain (Table 2).
Analysis of the deduced amino acid residues of the structural sequence revealed that all the Vietnamese CPV-2c and CPV-2a strains from this study contained the Arg116Lys, Leu125Ile, and Ala131Thr mutations in the VP1 sequence, and the Ala5Gly, Phe267Tyr, Tyr324Ile, and Gln370Arg mutations in VP2 in all Vietnamese CPV-2c strains, but no changes in Ala5Gly and Gln370Arg were seen in the Vietnamese CPV-2a strain. Interestingly, six Vietnamese CPV-2c variants (HN04, HN08, HN30, HCM01, HCM03, and HCM09) had the Thr112Ile and Ile447Met mutations in VP1 and VP2, respectively (Table 2).