Summary
Porcine circovirus 4(PCV4), a novel and unclassified member of the genus Circovirus ,
was first reported in China in 2019. Aimed at providing more evidence
about the active circulation of PCV4, this study screened 335 pooled
internal organs and detected the virus (i) at the rates of 3.28%, (ii)
from both clinical healthy and clinical sick pigs of various age groups,
and (iii) in six out of nice provinces of Korea. The complete genomic
sequence of a Korean PCV4 strain (E115) was 1,770 nucleotides in length
and had 98.5% to 98.9% identity to three PCV4 strains available at
GenBank up to date. Utilizing a set of bioinformatic programs, it was
revealed that the Korean PCV4 strain contained several genomic features
of (i) a palindrome stem-loop structure with conserved nonanucleotide,
(ii) packed overlapping ORFs oriented in different directions, and (iii)
two intergenic regions in between genes encoding putative replication-
associated protein (Rep) and capsid (Cap) proteins. This study also
predicted the presence of essential elements known so far for the
replication of circoviruses, for example, the origin of DNA replication,
endonuclease and helicase domains of Rep, the nuclear localization
signal on the putative Cap protein. Finally, based on the phylogeny
inferred from sequences of the putative Rep protein, it was suggested
that PCV4 belong to genus Circovirus of familyCircoviridae and losely related to three previous known porcine
circoviruses of PCV1, PCV2 and PCV3.