3.2 Similarity of the full-length genome, nucleotide and amino
acid sequence of NS and VP regions of Vietnamese CPV-2c
The complete full-length genetic sequences of various Vietnamese CPV-2,
ten CPV-2c (HN04, HN06, HN07, HN08, HN30, DN01, DN02, HCM01, HCM03, and
HCM09) and one CPV-2a (HCM16) strains were selected for sequencing using
multiple primer pairs for parvovirus to cover the whole genome. The
obtained full-length genome sequences of the Vietnamese CPV-2 variants
were submitted to GenBank (accession nos. MT106228–38). Sequence
analysis showed that the Vietnamese CPV-2c strains were highly similar
among strains, ranging from 99.5–99.8% in nucleotide similarity (Table
1, Supplementary Table S3a). Neither nucleotide differences nor specific
amino acid mutations were evident among the Vietnamese CPV-2c strains
detected from different geographic regions.
The complete genomes of the Vietnamese CPV-2c strains from this study
were found to be closely related to the recently isolated (in 2017)
Italian CPV-2c strain (MF510157) and the Chinese CPV-2a strain
(KR002800) isolated in 2014, with 99.6–99.8% and 99.3–99.5%
nucleotide identity, respectively. Meanwhile, the Vietnamese CPV-2c
strains were genetically distant from the previous Italian CPV-2c strain
(KU508407) isolated in 2009 and the single Vietnamese CPV-2a variant
isolated in this study, with 98.8–98.9% and 98.6–98.7% nucleotide
identity, respectively (Table 1, Supplementary Table S3a).
In addition, the nucleotide and amino acid sequence of the NS region
were similar between these Vietnamese CPV-2c strains, and the Italian
CPV-2c (MF510157) and Chinese CPV-2a (KR002800) strains, ranging from
99.7–100% similarity (Table 1, Supplementary Table S3b). Meanwhile,
there were different nucleotide and amino acid sequence similarities in
the VP region, accounting for 99.4–99.6% and 99.5–99.7%,
respectively, compared with MF510157, and 98.9–99.1% and 99.0–99.3%,
respectively, compared with KR002800. Whereas the Vietnamese CPV-2c
strains showed a lower degree of sequence similarity compared to
KU508407 and the single Vietnamese CPV-2a strain from this study (Table
1, Supplementary Table S3c).