Characterization of AcMNPV with a deletion of ac68 gene.

Orf68 (ac68) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is a highly conserved gene that codes a predicted 192-amino acid protein, but its function remains unknown. Results of the current study showed that ac68 was transcribed from 3 to 96 h and the protein was detected from 36 to 96 h post infection. An ac68 knockout bacmid was generated to investigate the role of the gene in baculovirus life cycle. Analyses of the production of infectious budded virus, occlusion bodies, and the formation of nucleocapsids revealed that there was no difference between the infection patterns of the mutant and its parent virus, or the ac68 repair virus. Bioassay with Trichoplusia ni demonstrated that deletion of ac68 did not affect AcMNPV infectivity, but extended LT(50) to a longer value. Taken together, our results indicated that the deletion did not affect viral propagation both in vitro and in vivo, but deletion of the gene may affect the virulence in T. ni larvae.