title: Autophagy enhances the replication of classical swine fever virus in vitro.
abstract: Autophagy plays an important role in cellular responses to pathogens. However, the impact of the autophagy machinery on classical swine fever virus (CSFV) infection is not yet confirmed. In this study, we showed that CSFV infection significantly increases the number of autophagy-like vesicles in the cytoplasm of host cells at the ultrastructural level. We also found the formation of 2 ubiquitin-like conjugation systems upon virus infection, including LC3-I/LC3-II conversion and ATG12-ATG5 conjugation, which are considered important indicators of autophagy. Meanwhile, high expression of ATG5 and BECN1 was detected in CSFV-infected cells; conversely, degradation of SQSTM1 was observed by immunoblotting, suggesting that CSFV infection triggered a complete autophagic response, most likely by the NS5A protein. Furthermore, by confocal immunofluorescence analysis, we discovered that both envelope protein E2 and nonstructural protein NS5A colocalized with LC3 and CD63 during CSFV infection. Examination by immunoelectron microscopy further confirmed the colocalization of both E2 and NS5A proteins with autophagosome-like vesicles, indicating that CSFV utilizes the membranes of these vesicles for replication. Finally, we demonstrated that alteration of cellular autophagy by autophagy regulators and shRNAs affects progeny virus production. Collectively, these findings provide strong evidence that CSFV infection needs an autophagy pathway to enhance viral replication and maturity in host cells.
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Pei
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Mingqiu
authors.initials: M
authors.lastname: Zhao
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Zuodong
authors.initials: Z
authors.lastname: Ye
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Hongchao
authors.initials: H
authors.lastname: Gou
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Jiaying
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Yi
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Dong
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Yongwen
authors.initials: Y
authors.lastname: Luo
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Liao
authors.affiliation: College of Veterinary Medicine; South China Agricultural University; Guangzhou, China.
authors.forename: Jinding
authors.initials: J
authors.lastname: Chen
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006691:Classical Swine Fever / Q000473:pathology / Q000821:virology; D006692:Classical Swine Fever Virus / Q000187:drug effects / Q000502:physiology*; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism / Q000648:ultrastructure; D034741:RNA, Small Interfering / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013552:Swine / Q000821:virology*; D014764:Viral Proteins / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D012367:RNA, Viral; D014764:Viral Proteins; C025946:3-methyladenine; D000225:Adenine; D020123:Sirolimus
keywords: BECN1; LC3; autophagy; classical swine fever virus (CSFV); replication