3.3. Phylogenetic analysis
For precise phylogenetic classification, the relationship of PCV4 with 7 families of CRESS DNA viruses (Rosario et al., 2012; L. Zhao et al., 2019) was inferred. The phylogenetic tree (inserted panel, Figure 7) revealed a similar tree topology between 7 families as in the previous publications (Kazlauskas et al., 2018; Krupovic et al., 2020). Based on that result, four PCV4 sequences (including E115 strain) were clustered within family Circoviridae . Using reference Rep sequences of genera Circovirus and Cyclovirus of the familyCircoviridae , all PCV4 strains were seen belonging to genusCircovirus (Figure 7). In consistency with the early classification (Tian et al., 2020; Zhang et al., 2020), this study confirmed that PCV4 is distantly related to previously known PCV1, PCV2 and PCV3.