Summary
Porcine circovirus type 4 (PCV4), a novel circovirus, was first detected
in pigs with porcine dermatitis and nephropathy syndrome (PDNS) in
China. This study investigated the frequency of porcine circovirus 4
(PCV4) in pigs in Guangxi Province, China, from 2015 to 2019 and its
genome diversity.
Thirteen
of 257 (5.1%) samples were positive for PCV4, 9 of 13 (69.2%)
PCV4-positive samples were coinfected with PCV2 or PCV3, and one
PCV4-positive sample was coinfected with both PCV2 and PCV3. Similar to
other PCVs, PCV4 contains two major ORFs and a stem loop (TTCAGTATTAC).
Multiple sequence alignments showed that the PCV4 genome shares
25.3-73.8% nucleotide similarity with
other representative circovirus
genomes. Interestingly, the PCV4 Cap protein shares relatively high
homology (approximately 50%) with the PCV2 Cap protein and has multiple
highly homologous peptides. Multiple amino acid sequence alignments of
the Cap protein revealed that PCV2 and PCV4 have multiple highly
homologous antigen sites and identical receptor binding sites.
Therefore, PCV2 and PCV4 may have cross-protective immunogenicity.
Phylogenetic analysis showed that PCV4 is closely related to mink
circovirus and bat-associated circovirus.
In summary, this was the first
seroprevalence and genetic investigation of PCV4 in Guangxi Province,
China. The results provide insights into the epidemiology and
pathogenesis of this important virus.
KEYWORDS: Porcine circovirus type 4; Porcine; Epidemiology;
Phylogenetic analysis