Dissimilar expression of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus polyhedrin and p10 genes

The temporal expression of the Autographa californica multiple nucleocapsid nuclear polyhedrosis virus polyhedrin and p10 genes in Spodoptera frugiperda cells was studied using virus recombinants in which either gene was replaced by the juvenile hormone esterase (JHE) gene of Heliothis virescens. The JHE served as a highly specific and sensitive reporter for gene expression. Activation of the p10 gene followed a pattern different to that of polyhedrin. The p10 gene was activated a few hours earlier than the polyhedrin gene, but its expression reached a lower maximum level. Northern blot analysis complemented and confirmed the results obtained from the JHE assays. Co-infection of sense recombinants and those containing an antisense copy of the JHE gene in place of the polyhedrin or p10 gene resulted in reduced levels of JHE gene expression. These experiments independently supported the hypothesis that the p10 gene promoter is more active at earlier times post-infection than that of the polyhedrin gene. The results also highlight the potential of the antisense strategy as an experimental approach for the study of baculovirus gene regulation and possibly insect metabolism.