Shan-Ying Wu: Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan. ORCID
Yu-Lun Chen: Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Ying-Ray Lee: Department of Microbiology and Immunology, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan. ORCID
Chiou-Feng Lin: Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan. ORCID
Sheng-Hui Lan: Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
Kai-Ying Lan: Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
Man-Ling Chu: Center for Cancer Research, Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Pei-Wen Lin: Center for Cancer Research, Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Zong-Lin Yang: Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
Yen-Hsu Chen: Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan. ORCID
Wen-Hung Wang: Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan. ORCID
Hsiao-Sheng Liu: Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Autophagic machinery is involved in selective and non-selective recruitment as well as degradation or exocytosis of cargoes, including pathogens. Dengue virus (DENV) infectioninduces autophagy that enhances virus replication and vesicle release to evade immune systemsurveillance. This study reveals that DENV2 induces autophagy in lung and liver cancer cells andshowed that DENV2 capsid, envelope, NS1, NS3, NS4B and host cell proinflammatory high mobilitygroup box 1 (HMGB1) proteins associated with autophagosomes which were purified by gradientcentrifugation. Capsid, NS1 and NS3 proteins showing high colocalization with LC3 protein in thecytoplasm of the infected cells were detected in the purified double-membrane autophagosome byimmunogold labeling under transmission electron microscopy. In DENV infected cells, the levels ofcapsid, envelope, NS1 and HMGB1 proteins are not significantly changed compared to the dramaticaccumulation of LC3-II and p62/SQSTM1 proteins when autophagic degradation was blocked bychloroquine, indicating that these proteins are not regulated by autophagic degradation machinery.We further demonstrated that purified autophagosomes were infectious when co-cultured withuninfected cells. Notably, these infectious autophagosomes contain DENV2 proteins, negativestrandand full-length genomic RNAs, but no viral particles. It is possible that the infectivity ofthe autophagosome originates from the full-length DENV RNA. Moreover, we reveal that DENV2promotes HMGB1 exocytosis partially through secretory autophagy. In conclusion, we are the firstto report that DENV2-induced double-membrane autophagosomes containing viral proteins andfull-length RNAs are infectious and not undergoing autophagic degradation. Our novel findingwarrants further validation of whether these intracellular vesicles undergo exocytosis to becomeinfectious autophagic vesicles.
