[Baculovirus p74 gene is a species-specific gene]

The p74 gene of Autographa californica multicasid nucleopolyhedrovirus (AcMNPV) bacmid was knockouted and substituted by the p74 gene of Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV), using RecA-mediated homologous recombination in the E. coli. No selection marker, which might influence the expression and function of p74 gene, was left in the modified p74 locus. The promoter of AcMNPV p74 gene directly controlled the expression of SpltMNPV p74 gene in the recombinant AcMNPV bacmid-polhSL74. RT-PCR showed that the substituted p74 gene was transcribed. Bioassay showed that the recombinant virus AcMNPV bacmid-polhSL74 could not infect the Argyrogramma agnata larvae per os, and thus showing the p74 gene is species-specific.