杆状病毒AcMNPV ac2 基因功能研究

his paper focused on the function of ac2 of AcMNPV, which is a bro gene. Bro(baculovirus repeat orf), a repeated gene commonly found in most baculovirus, shows great gene polymorphism as to its length, relative position, number of copies and even function in different genomes. Temporal transcription pattern of ac2 was described which displayed a typical late gene characteristic. Then the function analysis of ac2 by generation of ac2 deletion mutant virus with ET recombination and the Bac-to-Bac system in E coli was performed. Three recombinant viruses, ac2 deletion type (Ac-ac2-KO-GP), ac2 repair type (Ac-ac2-REP-GP), and wild type (Ac-GP) viruses were generated. Fluorescence microscopy showed that ac2 deletion had no apparent effect on spreading of BV. Optical microscopy showed that fewer OBs was observed in individual Sf9 cells transfected with ac2 deletion virus than wild type and ac2 repair virus.TCID50 assessment revealed a steady increase for ac2 defective virus titer but the ratio declined after 48 h.p.i., and BV yields was 100-fold lower at 96 h.p.i.. Electron microscopy observation exhibited single nucleocapsid enveloped in matured ODV. Thus, these results suggested that ac2 is not essential for BV production while it may enhance the process and play a role in ODV envelopment.