| Summary: | 碩士 === 國立成功大學 === 微生物及免疫學研究所 === 94 === Previous studies suggest that there are intratypic as well as intertypic cross-reactions among enteroviruses. Therefore, we hypothesized that this cross-reaction may play a role in the pathogenesis of Enterovirus 71 (EV71) infection. Because other study showing that Coxsackie A16 virus (CA16) and EV71 shared same epitopes, we chose CA16 as the intertypic enterovirus to test our hypothesis. One-day-old mice orally immunized with either avirulent EV71 strain (4643) or CA16 developed antibodies against EV71 with neutralization titer of 1:16 and 1:2, respectively. Both EV71 avirulent strain (4643)- and CA16-immunized mice were more resistant to subsequent challenge by virulent EV71 strain (MP4). Hyperimmune serum (HI) against CA16 contained antibodies that could bind EV71 antigens in both ELISA-based and indirect immuno-fluorescence assays. Furthermore, CA16 HI could neutralize EV71 but not Coxsackie B3 virus or poliovirus at a titer of 1:4. Passive immunization with CA16 HI reduced the clinical score, diminished organ viral load and increased survival rate of mice after EV71 challenge. Splenocytes from CA16-immunized mice proliferated and produced IFN-g upon EV71 or CA16, but not Coxsackie B3 antigen stimulation. These results illustrated that the immunity induced by CA16 indeed not only could cross react with EV71 but also offer partial protection against EV71. This intertypic reactivity of enteroviruses may play an important role in the pathogenesis of EV71.
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