Study On The Function Of BmNPV Orf59 Gene In Bombyx Mori Nucleopolyhedrovirus

Baculovirus is one of the largest and most practical groups in insect virus,it is a group of arthropod-specific virus.During the typical biphasic infection cycle,two structurally and functionally distinct enveloped virion phenotypes are produced,budded virus(BV)and occlusion-derived virus(ODV).Both virions have a common genetype,but differ in the phenotype,Baculovirus genome size is between 80 Kb and 180 Kb.Bombyx mori nucleopolyhedrovirus(BmNPV)is one of the family baculoviridae,most of the gene function has been reported,but there still some genes function is unknown.Bm59 gene is one of the core genes of NPVs.However,the role of Bm59 in the biological cycle of NPV remains unknown.The article is focused on the Bm59 gene,to study its influence on the replication,transcription,expression and assembly.In this study,the ?Red recombination system and the Bac-to-Bac system was used to create wild type virus wtBacmid-polh-egfp,knockout type virus Bm59ko-Bacmid-polh-egfp and repair type virus Bm59re-Bacmid-polh-egfp.We observed a significantly declined titer of progeny virus in Bm59ko-Bacmid-polh-egfp infected cells compared to that in wtBacmid-polh-egfp infected cells,whereas the titer of the progeny Bm59re-Bacmid-polh-egfp is comparable to that in wtBacmid-polhegfp infected cells.Transmission electron microscope shows that Bm59 deletion impacts on viral assembly.Furthermore,Quantitative polymerase chain reaction reveals that Bm59 deletion has a strong down-regulatory effect on viral DNA replication and exerts a strong down-regulatory effect on transcription levels of early gene lef3,late gene vp39,and very late gene p10.In addition,we built Bm59 protokaryotic expression vector and express fusion protein to study its time course of expressive.Western Blot analysis that Bm59 protein starts expression in the 48 h phase and the expression quantity is also increased.It obtained that the Bm59 is a late expression gene.These results indicate that Bm59 gene might serve as a non-essential factor for viral replication but play an important role in regulating gene transcription and viral assembly;further investigation is warranted,and Bm59 is a late expression gene.