腸病毒71型(Enterovirus 71,EV71)與克沙奇病毒A16(Coxsackievirus A16)為手足口病主要病原，好發於學齡前幼童， EV71與CVA16皆屬於微小核糖核酸病毒(Picornavirus)，兩者的3Dpol聚合酶(3Dpol polymerase)具有至少90%的相似度。本實驗室先前以腺病毒作為載體，插入EV71 3CD基因序列，打入h-SCARB2轉基因老鼠成功抵抗EV71以及CVA16，顯示3Dpol可能具有的保護力。在本研究中，建立重組3Dpol之質體建構並且以大腸桿菌進行生產。首先，接種單純3Dpol的h-SCARB2小鼠無法存活於CVA16攻毒。接著，將3Dpol混合R848、IFA或ISA-51對小鼠接種，發現3Dpol/R848可以保護小鼠於EV71攻毒，而3Dpol/IFA可以保護小鼠於CVA16攻毒，並且3Dpol/ISA-51可以交叉保護小鼠於EV71或CVA16攻毒。其中，接種3Dpol/R848或3Dpol/ISA-51之小鼠其脾臟能表現較高水準之IL-4與IL-17a，然而不管是接種3Dpol/R848、3Dpol/ISA-51或是3Dpol/IFA，都表現較少IFN-gamma。同時，接種3Dpol/ISA-51之小鼠，其體內的CD4+ T cell有被負向調節的現象。最後，從3Dpol/R848、3Dpol/ISA-51或3Dpol/IFA接種之小鼠取得之血清，無法降低EV71造成之細胞病變現象。這些數據顯示3Dpol搭配佐劑不只能保護小鼠免於感染，並可能對IFN-gamma+CD4+ and IL-4+CD4+ T cell有克隆選擇之作用。

Enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) are the major causative for hand, foot and mouth disease, a common disease found on children. EV71 and CVA16 are the member of the picornaviridae family. Their 3Dpol polymerase share 90% of homology at least. Previously, an adenovirus, inserted with 3CD sequence, was developed in our lab and found that being able to protect h-SCARB2 mice from EV71 and CVA16. This finding suggests that the protective ability might be distributed by 3Dpol. First, in this research, the construct of recombinant 3Dpol was developed and produced. Then, the h-SCARB2 mice were immunized with 3Dpol alone and no mice survived under CVA16 subsequent challenge. Afterwards, the 3Dpol was mixed with R848, IFA and ISA-51. Results showed that 3Dpol with R848 or IFA can protect h-SCARB2 mice from EV71 or CVA16 respectively. Most importantly, 3Dpol mixed with ISA-51 can cross protect h-SCARB2 mice from both EV71 and CVA16. Besides, the Th2 and Th17 cytokine were expressed higher by the splenocytes immunized with 3Dpol/ISA-51 and 3Dpol/R848. However, the expression level of IFN-γ was decreased and the CD4+ T cell proliferation was down-regulated. Final, the serum derived from 3Dpol/R848, IFA or ISA-51 could not reduce the cytopathic effect caused by EV71. These results suggest that the 3Dpol with adjuvant not only can protect mice from infection but also may contribute to the clonal selection of IFN-gamma+CD4+ and IL-4+CD4+ T cell.

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