Microplitis Bicoloratus Bracovirus Regulates Eukaryotic Translation Initiation Factor EIF4A And EIF4E

It has been studied on the mechanism in which bracoviruses inhibits the host’s immune response during its parasitic process.Further,it has been reported that Mb BV inhibited host immune response by inducing apoptosis of S.litura hemocytes.However,the mechanism how Mb BV regulates the apoptosis of S.litura hemocytes to suppress the host immune response remains unclear.The purpose of this study was to investigate whether Mb BV promotes the apoptosis of S.litura hemocytes and inhibits the development of S.litura larve by controlling the expression of translation initiation factors e IF4 A and e IF4 E.We obtained the following research results: Firstly,we founded that Mb BV inhibited the expression of e IF4 A and induced apoptosis of S.litura hemocytes.So,we regarded e IF4 A as a target gene of Mb BV for the further study.And we founded that RNAi of e IF4 A promoted the apoptosis of S.litura hemocytes induced by M.bicoloratus parasitism,and overexpression of e IF4 A rescued the apoptosis of High Five cells induced by Mb BV virions.Therefore,we thought that Mb BV regulated apoptosis by regulating the expression of e IF4 A.Then,analysis of S.litura transcriptome data revealed that e IF4 E m RNA level was down-regulated after M.bicoloratus parasitism.So,we regarded e IF4 E as a target gene of Mb BV for the further study.It was found that overexpression of e IF4 E could significantly rescue the apoptosis of High Five cells induced by Mb BV virions,while the RNAi of e IF4 E significantly promoted the apoptosis of S.litura hemocytes induced by M.bicoloratus parasitism.And analysis of S.litura larvae head capsule width data revealed that the RNAi of e IF4 E promoted the inhibition of M.bicoloratus parasitism on the development of S.litura larvae head capsule.Therefore,we thought that Mb BV regulated apoptosis and inhibited the S.litura larve growth and development by regulating the expression of e IF4 E.In the end,we used the methods of dual gene silencing and co-transfection to study the differences in regulation of e IF4 A and e IF4 E by Mb BV,and it was found that the regulation effect of Mb BV on e IF4 E was more pronounced.In summary,this study clarified the molecular mechanism of Mb BV induced the apoptosis of the S.litura hemocytes and inhibited the growth and development of S.litura larve by inhibiting the expression of initiation factor e IF4 A and e IF4 E.This study provides new ideas for immunization research and provides a new theoretical basis for the prevention and control of S.litura biological pests.