| Summary: | 碩士 === 國立成功大學 === 微生物暨免疫學研究所 === 88 === Abstract
The clinical syndromes of Enterovirus 71（EV71）infection include hand-foot-mouth disease, herpangina, aseptic meningitis, poliomyelitis-like paralysis and fatal encephalitis. The pathogenesis and tissue tropism of enterovius infection are still poorly understood. Our objectives are to examine EV71 infection in four mammalian cell lines：Vero（Africa green monkey kidney）, SK-N-SH (human neuroblastoma), U373MG (human glioblastoma), and HEp-2 (human larynx epidermoid carcinoma) for clarifying viral tissue tropism. We observed the cytopathic effect (CPE) using phase contrast microscope and electronmicroscope, the synthesis of infected cell specific proteins (ICSPs), viral RNA negative strand synthesis, and virus replication rates in the cells. In addition, we also use microarray assay to examine the cellular genes influenced by EV71 infection. EV71 infection caused obvious CPE at a M.O.I. of 100 in Vero and SK-N-SH cells at 48 h postinfection (p.i.). The cells became rounding-up, aggregated together, and finally died. In contrast, the CPE was very mild in HEp-2 and U373MG cells. The severity of EV71 CPE in various cell lines in general corresponded with ICSPs expression, viral negative strand RNA synthesis and virus replication rates. In the EV71-infected Vero and SK-N-SH cells, 14 ICSPs and 8 ICSPs could be detected, respectively. Their molecular weights were range from 25 kDa to 78 kDa starting at 24 h p.i. One ICSP in U373MG cells and two ICSPs in HEp-2 were detected while the labeling time was extended to 6 h. Slot blot analysis revealed that EV71 could replicate in all cells. The electronmicrographs showed that EV71 could replicate in four cell lines, and caused cell chromatin condensation, vacuolation and cellular surface protusions. Further more, the virus replication rates reached 108 PFU per ml within 48 h p.i. in Vero and SK-N-SH cells and the titer in HEp-2 and U373MG cells were 105 and 104, respectively. Microarray assay data displayed that at least 12、7 and 12 genes were influenced in SK-N-SH、HEp-2 and U373MG cell lines, respectively. Ten genes such as Oct-1 were specially induced in EV71 infected SK-N-SH cell lines. In conclusion, we demonstrated that EV71 infection of SK-N-SH cell showed specifically neurotropism and neurovirulence for the excellence in efficient viral proteins and RNA expression ability in life cycle. This finding may explain the unusual pathogenesis of EV71 infection.
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