Baculovirus has many advantages as vectors for gene transfer.We demonstrated that recombinant baculovirus vectors expressing p35(Ac-CMV-p35) and eGFP(Ac-CMV-GFP) could be transduced into human kidney 293 cells efficiently.The level of transgene expression was viral dose dependent and high-level expression of the target gene could be achieved under the heterogonous promoter.MTT assay suggested that both Ac-CMV-p35 and Ac-CMV-GFP did not have cytotoxic effect on human embryo kidney 293 cells.Cell growth curve showed the Ac-CMV-p35 and Ac-CMV-GFP transduced and non-transduced cells had similar proliferation rate,so baculovirus-mediated p35 expression had no adverse effect on cell proliferation.In addition,baculovirus-mediated p35 gene expression protected human embryo kidney 293 cells against apoptosis induced by various apoptosis inducers such as Actinomycin D,UV or serum-free media.These results suggested that the baculovirus vector mediated p35 gene expression was functional and it could be widely used in molecular research and even gene therapy.
The Autographa californica nucleopolyhedrovirus(AcMNPV) contains three apoptosis suppressor genes:p35,iap1 and iap2.AcMNPV P35 functions as a pancaspase inhibitor,but the function of IAP1 and IAP2 has not been entirely resolved.In this paper,we analyze the function of IAP1 and IAP2 in detail.AcMNPV with p35-deletion inhibited the apoptosis of BTI-Tn-5B1-4(Tn-Hi5) cells induced by a Helicoverpa armigera single nucleocapsid NPV(HearNPV) infection and rescued the replication of HearNPV and BV production in these cells.Transient-expression experiments indicated that both IAP1 and IAP2 suppress apoptosis of Tn-Hi5 cells during HearNPV infection.Recombinant HearNPVs expressing AcMNPV iap1,iap2 and p35,respectively,not only prevented apoptosis but also allowed HearNPV to replicate in Tn-Hi5 cells.However,the iap1,iap2 and p35 genes when expressed in HearNPV were unable to rescue BV production.These results indicate that both AcMNPV iap1 and iap2 function independently as apoptosis inhibitors of and are potential host range factors.
Fibroblast growth factor (FGF) is a key regulator of developmental processes. A FGF homolog (vFGF) is found in all lepidopteran baculoviruses. Autographa californica nucleopolyhedrovirus (AcMNPV) and Bombyx mori NPV (BmNPV) vFGFs are chemotactic factors. Here we analyzed the vfgf of Helicoverpa armigera NPV (HearNPV), a group II NPV. The HearNPV vfgf transcripts were detected from 18 to 96 h post-infection (hpi) of Hz-AM1 cells with HearNPV and encoded a 36 kDa protein, which was secreted into the culture medium. HearNPV vFGF had strong affinity to heparin, a property important for FGF signaling via an FGF receptor. Unlike its AcMNPV homolog, HearNPV vFGF specially chemoattracted Hz-AM1, but not other insect cells such as Sf9 and Se-UCR and not the mammalian cells 293 and HepG2. HearNPV vFGF is also associated with the envelope of BV but is absent in occlusion-derived virus, which coordinated to the chemotatic activity analysis.
Xiang LI Chang-yong LIANG Jian-hua SONG Xin-wen CHEN
