Detection and sequencing of porcine circovirus 3 in commercially sourced laboratory mice

Porcine circovirus 3 ( PCV 3), a recently discovered virus, has spread widely in pigs throughout the world. In order to investigate the possibility of mice used to study the infection of PCV 3, commercially sourced Balb/C and ICR mice were screened for PCV 3 infection. Blood samples were collected from 20 mice (10 each of Balb/c and ICR ), DNA was extracted, and subjected to PCR with PCV 3 specific primers. We found all 20 serum samples tested positive for PCV 3 DNA . From four mice, the complete genomes of PCV 3 were amplified and sequenced, and a phylogenetic tree was constructed. The results showed that the amplified genome was 2000 bp, and sequence comparison showed that the homology of the complete genome and ORF 2 gene with those of porcine PCV 3 are 97.9%–98.8% and 96.9%–98.3%, respectively. Amino acids alignment results showed that the Cap protein of the mouse PCV 3 isolates share 90.7%–96.3% amino acid homology with that of the references strains derived from pigs. Phylogenetic analysis based on ORF 2 sequences showed that all PCV 3 strains clustered together and were clearly separate from other circovirus species. We detected PCV 3 in experimental mice in China for the first time, which is an opportunity to use mice to study the infection of PCV 3 and a potential hazard to swine industry.