| Baculovirus is a divers group of arthropod viruses. It has been widely used as an environment sound biopesticide and a eukaryotic expression tool. Since the baculoviral P35 and IAPs, an evolutionarily conserved gene family involved in regulation of apoptosis, were found to inhibit apoptosis of insect cells baculoviruses also provide an ideal system to study the effects of an apoptotic response on viral pathogenesis.In the thesis we report that Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) induced Tn-Hi5 cell apoptosis, which was blocked by both wild type and p35 deleted mutant of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). Futhermore both AcMNPV w.t.and p35 null rescued HaSNPV replication in Tn-Hi5 and produced infective virus. This means that HaSNPV extend the host rang with AcMNPV help. It also suggests that AcMNPV has at least one functional apoptosis inhibitor gene other than p35. As the AcMNPV genome contains two iaps: Aciap1 and Aciap2, we wonder if they are functional in Tn-Hi5. The transient expression assay indicated that Aciap2 could partially inhibit the Tn-Hi5 apoptosis induced by HaSNPV, while iap1 did not show the function of apoptosis inhibition. Then we constructed the recombinant HaSNPVs which overexpression of either p35, Aciap1 or Aciap2 to futher analyse IAP function and to achive the host range extended HaSNPV. Both vHap35 and vHaiap2 could infect Tn-Hi5 without distinctness apoptosis, but vHaiap1 still induce Tn-Hi5 cell apoptosis. Not as we expection, vHap35 and vHaiap2 could not produce infective BV in Tn-Hi5, but we observed viral particles under the electronic microscope, which probably are the ODVs. The results demonstrat that both p35 and iap2 gene can inhibit the apoptosis of Tn-Hi5 cells. It also suggests that more AcMNPV factors are needed to resuce the full replication of HaSNPV in Tn-Hi5 cells. |
