Study On The Function Of Baculovirus AcMNPV Ac124Gene

AcMNPV is the type species of baculoviruses and best understood as it was first sequenced in full genome and lots of researches were reported. In order to make better application of the baculovirus, functions of many genes are revealed but some genes are still unclear. The function of ac124, a highly conserved gene in baculovirus, is unknown. Homologs of ac124are present in the genomes of all currently sequenced Group I lepidopteran NPVs. In this paper, ac124gene was selected as the research object and Red-recombination system as well as bac-to-bac system was used to constructed ac124gene knockout recombinant virus. Its influence on the virus assembly, replication and virus-infected larvae were analyzed. The subcellular localization of Ac124was also characterized.The first chapter describes the current understanding of the baculovirus, mainly through the following several aspects:baculovirus taxonomy, infection cycle, genome, the application of baculovirus mostly as pesticides and baculovirus expression system, background of ac124genes as well as the purpose and significance of this paper.In chapter two, the recombinant virus vAcacac24-ko-PH-PG virus (deleted with ac124) and vAcac124-rep-PH-PG (virus rescued with ac124) were constructed by Red-recombination and bac-to-bac system. vAcac124-ko-pH-pG, vAc8ac124-rep-PH-PG and vAcPH-PG (wild type virus) transfected or infected sf9cells showed the same density of green fluorescence means those three viruses could generate similar BVs. There were no significant differences in polyhedra formation under the microscope. Three viruses infected cells with the same MOI. All of the three viruses showed similar one-step growth curve. Electron microscopy showed the similar nucleocapsid in vAcac124-ko-PH-PG-infected cells and in vAcPH-PG-infected cells. In summary, knockout ac124gene did not affect the production of BV and ODV that means AcMNPV ac124is not essential for virus replication.In chapter three, the bioassay experiment was performed with Spodoptera exigua larvae. The results showed that LT50of vAcac124-ko-PH-PG was20h longer than that ofvAcPH"PG. Those results indicate that AcMNPV ac124gene has a certain impact on the speed of insecticidal.The fourth chapter studied subcellular localization of Ac124. Under confocal microscopy, Ac124was localized in the cytoplasm, suggesting that Ac124could be associated with BV budding, BV envelope formation or infected insect hosts. Maybe it has nothing to do with nucleocapsid assembly and the viral DNA replication.Chapter five is about the conclusion and discussion of the paper.Above all, ac124is a non-essential gene for the replication of baculovirus, but has affected the insecticidal speed of the baculovirus, suggesting the new research direction that how the AcMNPV ac124impact on the baculovirus killing insects.