Infection Of PCV2 In Human Cell Lines And RNA-Sequence Analysis

Under the rapid development of the emerging medical industry,pigs are more preferred to be the donor source for xenotransplantation because of its organs are similar to human in size and function.In addition,except two major pathogens,Porcine endogenous retrovirus(PERV)and Porcine cytomegalovirus(PCMV),that affect the success of xenografts most,the infectious of Porcine circovirus(PCV)in human cells is still unknown.PCV2 is one of the important pathogens of swine,resulting in devastating disease and huge economic losses worldwide.There is still much controversy in the safety of the organs from pigs which is infected by PCV2.Due to the emergence of PCV2 variant,the occurrence of new epidemic of PCV2 become more and more frequent,resulting in the PCV2 infections more widespread in wild swine across the world.Xenotransplantation has developed rapidly.It has been unanimously recognized worldwide that swine is the best donor source of xenograf.Therefore,it is important for the further application of xenotransplantation to determine whether PCV2 has infectivity and pathogenicity to humans.In particular,it is necessary to consider the immunosuppressive effect of PC2 on the host when use swine as the donor source of xenograf.In present study,we aimed to verify in vitro infection of PCV2 in human cell lines using the SYBR Green real-time quantitative PCR,Western blot and indirect immunofluorescence methods.PCV2 CC1 strain and 12 human cell lines were used in this study.The results showed that human cell lines can be infected by PCV2,and the classical PCV virions can be observed in the virus-infected cells.The infection of PCV2 to human cell lines is productive,and the generated virions still has the ability to infect the other human cells.However,the infection of PCV2 in human cell lines was self-limited and the infection efficiency of PCV2 was lower in human cells compared with that of PK-15 cell.RNA-Seq revealed that the expression of some genes in infected PK-15 and HeLa cells showed significant difference with non-infected cells,especially chemokines and inflammation genes,which are related to inflammation and immune response in host.The expression of key genes involved in the signaling pathway also showed significant differences between infected and non-infected cells.Because the mechanism of PCV2 infection of human cell lines is still unclear,therefore,the reason for the self-limiting proliferation of PCV2 in human cell lines remains to be further explored.