Nearly full-length genome characterization of canine parvovirus strains circulating in Nigeria.

Canine parvovirus type 2 (CPV-2) emerged suddenly in the late 1970s as pathogen of dogs, causing a severe and often fatal gastroenteric disease. The original CPV-2 was replaced by three antigenic variants, CPV-2a, CPV-2b and CPV-2c, which to date have gained a worldwide distribution with different relative proportions. All previous studies conducted in Africa were based on partial VP2 gene sequences. The aim of this study was to provide a genome analysis to characterize the CPV strains collected in Nigeria, Africa. Rectal swab samples (n = 320) were collected in 2018 and tested by means of an immunochromatographic assay. Among the 144 positive samples, 59 were selected for further analyses using different molecular assays. The results revealed a high prevalence of CPV-2c (91.5%) compared to the CPV-2a variant (8.5%). The VP2 gene sequences showed a divergence from the strains analysed in 2010 in Nigeria and a closer connection with CPV strains of Asian origin. The non-structural gene analysis evidenced amino acid changes never previously reported. The molecular analysis based on genomic sequences evidenced a geographical pattern of distribution of the analysed strains, suggesting a potential common evolutionary origin with CPV of Asian origin. This study represents the first CPV molecular characterization including all the encoding gene sequences conducted in the African continent and contributes to define the current geographical spread of the CPV variants worldwide.