Fig. 3. Phylogenetic analysis of VP2 gene sequences from pangolin and related parvoviruses. The ML tree was constructed based on VP2 gene sequences of 142 parvoviruses belonging to the species Carnivore protoparvovirus 1 (FPV [n = 3]; CPV-2 [n = 14] or its variants CPV-2a [n = 68], CPV-2b [n = 8], or CPV-2c [n = 52]). The VP2 gene sequences of FPV were used as an outgroup and rooted by the oldest FPV sequence (FPV/Cat/US/FPV-d/64, U22189). The two pangolin parvovirus isolates obtained in this study are indicated by red triangle, and the reference virus is denoted by a black triangle. Details of the several subclades grouped close to CPV-2b or CPV-2c are presented in Fig S1. The scale bar shown at the bottom of the tree denotes.
Pangolins remain critically endangered worldwide, owing to a range of threats, not least of which is pathogen infection. To date, however, there have been few studies that have examined the pathogens infecting pangolins. In this study, however, we were able to confirm CPV-2c infection among pangolins inhabiting mainland China and established that these animals can also be infected with the CPV-2a variant. In this regard, the findings of previous studies have provided evidence to indicate that CPV frequently undergoes interspecies transmission among domestic and wild animals, with asymptomatic individuals (e.g., stray dogs and raccoons) inhabiting the peripheries of urban areas acting as virus reservoirs that promote the spread of CPV-2 to wild animals (Allison et al., 2012; Allison et al., 2013; Hirsch, Prange, Hauver, & Gehrt, 2013). Notably, the two strains detected in this study are phylogenetically close to CPV strains derived from dogs. Moreover, stray dogs have been observed attacking wild pangolins in areas in which urban development has encroached on the habitats of these animals (S. L. Wang et al., 2020), thereby indicating the potential for cross-species transmission between stray dogs and wild pangolins.
In summary, in this study, we report the infection of Chinese pangolins with two strains of canine parvovirus type 2 causing diarrheal diseases. These two CPV-2 strains are closely related to CPV-2a and CPV-2c, which are prevalent in China and neighboring countries, respectively, thereby revealing that the CPV-2 strains infecting Chinese pangolins are related to those known to be of dog origin. Based onour findings, we recommend that further investigations should be conducted to assess the potential interspecies transmission among wild Chinese pangolins and domestic or feral dogs.