Resolving the Phylogenetic Placement of the FSfaCV/PCV5-Related Viruses Within the Genus Macochavirus.

Metagenomic analysis of fecal samples from diarrheic pigs in China identified 10 complete circular single-stranded DNA viral genomes previously designated as putative porcine circovirus 5 (PCV5)-like viruses. Genome characterization revealed a typical cressdnavirus organization with bidirectionally oriented Rep and Cap genes. Phylogenetic analyses based on complete genomes and encoded proteins showed that these viruses do not cluster with members of Circoviridae but instead form a distinct lineage within the family Pecoviridae, closely related to the genus Macochavirus. Sequence identity, genetic distance, and nucleotide diversity analyses supported their classification as a coherent viral group. Comparative analyses indicated greater sequence divergence in the Rep region than in the Cap region. These findings support reclassification of putative PCV5 as a porcine-associated lineage within the genus Macochavirus, designated porcine Macochavirus (PMV), thereby resolving their long-standing taxonomic ambiguity and expanding the recognized diversity of cressdnaviruses within the family Pecoviridae.