Reservoirs of Porcine Circoviruses: A Mini Review

Zhai, Shao-Lun; Lu, Shou-Sheng; Wei, Wen-Kang; Lv, Dian-Hong; Wen, Xiao-Hui; Zhai, Qi; Chen, Qin-Ling; Sun, Yan-Wei; Xi, Yun

PCV1 was first confirmed as a contaminant in porcine kidney cell lines (1), following which, non-infectious PCV1 and PCV2 were detected in porcine-derived commercial pepsin products used for humans (66) . Owing to its porcine origin, the detection of PCVs in pepsin and other porcine biological products is perfectly plausible. PCV1 was also reported in commercial veterinary vaccines against classic swine fever virus (CSFV), porcine parvovirus (PPV), and pseudorabies virus (PRV) (67, 68) . However, in 2010, PCV1 was reported in human rotavirus vaccine (69) , which caused a significant stir because of unknown clinical significance of PCVs in humans. Since that incident, the Food and Drug Administration (FDA) and several research institutions began investigating the source of the vaccine contamination and assessing the safety of the vaccine. Their results indicated that several cell lines, virus seeds and vaccines were contaminated by PCV1 and/or PCV2 (70) (71) (72) (73) (74) (75) . Porcinederived commercial pepsin product used for cell culture and vaccine production was considered as the main source of vaccine contamination (76) . Although the contaminated vaccines caused no clinical diseases in people, humans can be considered likely reservoirs for PCVs (63, 77) . Thus, via human fecal matter, PCVs might have been introduced into environmental water or other places (64).