Abstract
Autophagy is an evolutionarily ancient pathway that has been shown to be important in the innate immune defense against several viruses. However, little is known about the regulatory role of autophagy in transmissible gastroenteritis virus (TGEV) replication. In this study, we found that TGEV infection increased the number of autophagosome-like double- and single-membrane vesicles in the cytoplasm of host cells, a phenomenon that is known to be related to autophagy. In addition, virus replication was required for the increased amount of the autophagosome marker protein LC3-II. Autophagic flux occurred in TGEV-infected cells, suggesting that TGEV infection triggered a complete autophagic response. When autophagy was pharmacologically inhibited by wortmannin or LY294002, TGEV replication increased. The increase in virus yield via autophagy inhibition was further confirmed by the use of siRNA duplexes, through which three proteins required for autophagy were depleted. Furthermore, TGEV replication was inhibited when autophagy was activated by rapamycin. The antiviral response of autophagy was confirmed by using siRNA to reduce the expression of gene p300, which otherwise inhibits autophagy. Together, the results indicate that TGEV infection activates autophagy and that autophagy then inhibits further TGEV replication.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Androstadienes / pharmacology
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Animals
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Antibodies, Monoclonal / pharmacology
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Autophagy / drug effects
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Autophagy / genetics*
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Autophagy-Related Protein 5 / antagonists & inhibitors
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Autophagy-Related Protein 5 / genetics
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Autophagy-Related Protein 5 / metabolism
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Autophagy-Related Protein 7 / antagonists & inhibitors
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Autophagy-Related Protein 7 / genetics
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Autophagy-Related Protein 7 / metabolism
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Cell Line
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Chromones / pharmacology
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Cytoplasmic Vesicles / drug effects
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Cytoplasmic Vesicles / metabolism
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Cytoplasmic Vesicles / virology
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Epithelial Cells / drug effects
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Epithelial Cells / metabolism
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Epithelial Cells / virology*
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Gene Expression Regulation
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Host-Pathogen Interactions*
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Microtubule-Associated Proteins / antagonists & inhibitors
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism
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Morpholines / pharmacology
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Phagosomes / drug effects
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Phagosomes / metabolism
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Phagosomes / virology
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Signal Transduction
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Sirolimus / pharmacology
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Swine
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Transmissible gastroenteritis virus / pathogenicity
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Transmissible gastroenteritis virus / physiology*
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Virus Replication / drug effects
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Wortmannin
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p300-CBP Transcription Factors / antagonists & inhibitors
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p300-CBP Transcription Factors / genetics*
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p300-CBP Transcription Factors / metabolism
Substances
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Androstadienes
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Antibodies, Monoclonal
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Autophagy-Related Protein 5
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Chromones
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Microtubule-Associated Proteins
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Morpholines
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RNA, Small Interfering
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2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
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p300-CBP Transcription Factors
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p300-CBP-associated factor
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Autophagy-Related Protein 7
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Sirolimus
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Wortmannin