Abstract
Porcine circovirus type 3 (PCV-3) had posed a potential threat to the
swine industry since its discovery in the United States in 2015. The
Shanxi province had a wide range of large-scale pig farms in China, but
the transmission of PCV-3 was unclear. To further investigate the
epidemic profile and genetic diversity of the virus, the lung samples
(491) from 19 different pig slaughterhouse in 11 cities covering the
whole of the Shanxi province of China were evaluated by PCR. The results
indicated that the PCV-3 positive rate at the slaughterhouse level and
at the individual level was 100% (19/19) and 86.76% (426/491),
respectively. The PCR-positive samples were further sequenced, and eight
new PCV3 isolates were identified. The complete genomes of the eight
virus isolates showed 97.45%–99.90% nucleotide identity with other
PCV-3 isolates available in NCBI. Phylogenetic analysis based on the
complete genome and capsid gene divided the PCV-3 strains into two main
groups and several subclusters. The eight identified PCV-3 strains could
be divided into the same clades, according to amino acid mutations A24/V
and R27/K of Cap proteins. The results could provide new insight into
the prevalence and genetic variation of PCV-3 in the Shanxi province of
China, as well as the possibility of transmission from this center. It
also reminded me that the molecular epidemiology of this new circovirus
was urgent.