4.1. The detection of PCV4
After the first report of PCV4 in the Hunan province, China (Zhang et
al., 2020), the virus was also detected in other provinces of China
(Tian et al., 2020). The presence of PCV4 in
different geographic locations
implied the active circulation of the virus. However, a preliminary
screening failed to detect PCV4 in two European countries (Franzo et
al., 2020). With the detection rates of 3.28% in six out of nine
provinces in Korea (Figures 1A- 1B), this study provided further
evidence for the prevalence of PCV4 in pigs. Combining the detection
results of the first two publications (Tian et al., 2020; Zhang et al.,
2020) and this report (Figure 1C), it was noteworthy to observe that
PCV4 was present in pigs of all age groups and in both clinically
healthy and different clinically diseased pigs. That fact was similar to
PCV2 and PCV3 infections which were found in pigs with different
clinical presentations (Segales, 2012; Zhai et al., 2017). Further
studies are required to elucidate any association with diseases in pigs
of this novel PCV4.