Enterovirus 71-induced autophagy detected in vitro and in vivo and its role in pathogenesis

• Main Authors: Po-ShunWang, 王柏舜
• Other Authors: Hsiao-Sheng Liu
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/29872958334246355055

碩士 === 國立成功大學 === 微生物及免疫學研究所 === 98 === Enterovirus 71 (EV71) is a non-enveloped positive single-stranded RNA virus, which belongs to the family Picornaviridae. EV71 is an important etiological agent causing sudden death of young children in recent global outbreak. Currently, there is no effective antiviral therapy or vaccines against EV71 infection. Autophagy is an evolutionarily conserved lysosomal process for the degradation and recycling long-lived proteins and damaged organelles in host cells and plays a crucial role in virus infection. We reported that EV71 induces autophagy in muscle RD and neuron SK-N-SH cells. EV71 also induces autophagosome-like vesicles in the cervical spinal neurons of infected suckling mice. (J. Med. Virol. 81:1241-52, 2009). In this study, we demonstrate that EV71 VP1 expression was induced by the autophagy inducer tamoxifen and inhibited by the inhibitor 3-methyladenine (3-MA), indicating that EV71-induced autophagy is beneficial for viral replication. Phosphorylation of extracellular signal-regulated kinase (p-Erk) was suppressed by EV71 infection. However, p-Erk did not participate in EV71-induced autophagic process. EV71 induced co-localization of LC3 and lysosomal-associated membrane protein 1 (LAMP1) protein, and co-localization of LC3 and mannose-6-phosphate receptor (MPR), indicating the amphisome (fusion of endosome and autophagosome) formation. Furthermore, co-localization of LC3 and EV71 2C, LC3 and 3A suggests that EV71 2C and 3A are involved in host autophagic response. Blockage of the fusion of autophagosome and lysosome by NH4Cl and vinblastine caused LC3 accumulation, indicating that EV71 infection triggers the autophagic flux. Transcription factor early growth response 1 (Egr-1) was increased following EV71 infection and associated with LC3 expression, suggesting that Egr-1 may promote autophagy in response to EV71 infection. Intriguingly, in EV71-infected suckling mice, the expression levels of VP1 and LC3 proteins were highly expressed from 12 hr p.i. in the brain neurons. The body weight was increased and disease severity of the mice was attenuated at the early stage after 3-MA treatment. Furthermore, EV71 titer was also suppressed. It suggests that autophagy is involved in EV71-related pathogenesis and promote viral replication. In conclusion, we reveal a potential role of EV71-induced autophagy in viral pathogenesis both in vitro and in vivo.