Mechanism Of Helicoverpa Armigera Nucleopolyhedrovirus Triggered Se-UCR Apoptosis Blocked By Spodoptera Exigua Nucleopolyhedrovirus

This paper reports that Helicoverpa armigera single nucleocapsidae nucleopolyhedrovirus (HaSNPV) could trigger a Spodoptera exigua cell line Se-UCR apoptosis which could be blocked by S. exigua nucleopolyhedrovirus (SeMNPV). Two HaSNPV recombinants, which express Se-IAP2 and Se-IAP3, were constructed and used to analyze if SeMNPV IAPs are functional. This thesis contains three chapters.Chapter one is a general introduction of baculovirus and apoptosis. Here we introduce the classification, life cycle, characteristics of genome and normal use of baculovirus. On the other hand, signal pathway in apoptosis, common apoptosis detection methods, reviews of IAP and newly research progress of baculovirus in apoptosis are also mentioned. The phenomenon that HaSNPV could trigger a S. exigua cell line Se-UCR apoptosis which could be blocked by SeMNPV was reported in chapter two. When Se-UCR infected with HaSNPV, the apoptotic body was first found at 12 hpi, obvious apoptosis could be observed at 24 hpi, at the end almost all cells were dead at 72 hpi. Those observations were proved by genome DNA fragmentation analysis. If coinfected Se-UCR with HaSNPV and SeMNPV, we could not detected apoptosis. And more, if Hacxw1, which containing GFP, was used in the coinfection and theGFP were expressed indicating that HaSNPV could replicate in Se-UCR with the help of SeMNPV in Se-UCR. Dot blot analysis found that SeMNPV could help HaSNPV genome DNA replication in Se-UCR cells. It is notable that HaSNPV neither induce Se-301, a cell line also from S. exigua, apoptosis, nor replicated in Se-301 even coinfected with SeMNPV.Chapter three is primary functional analysis of two SeMNPV iap genes: Se-iap2, Se-iap3. To construct recombinant HaSNPV viruses carrying Se-iap genes under control of a heat shock promoter, different transfer vectors were generated. The recombinants vHaSeiap2 containing Se-iap2 and vHaSeiap3 carrying Seiap3, were made by either Bac-to-Bac system or the homologue recombination system. Then the recombinants were used to infect Tn-Hi5, which go to apoptosis after infected with HaSNPV. vHaSeiap3 still induced Tn-Hi5 apoptosis, while the apoptosis level decreased by vHaSe-ap2. This data indicate that Se-iap2 can partially block Tn-Hi5 apoptosis induced by HaSNPV, but not Se-iap3. The major reason might be that the recombinant vHaSeiap3 is not purified yet.