Analysis of the Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus trans-activators IE-1 and IE-2 using monoclonal antibodies.

We have produced monoclonal antibodies against two Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV) transcriptional trans-activators, IE-1 and IE-2. Temporal analysis of IE-1 and IE-2 proteins have shown that IE-1 continues to increase in steady-state levels from 0 to 120 h post-infection, whereas IE-2 declines by 36 h post-infection. At least five different electrophoretic forms of IE-1 are present in OpMNPV-infected LD652Y cells of which three appear to be from the non-spliced IE-1 gene. Cotransfection experiments also showed that IE-1 causes a reduction in the levels of IE-2 protein but concurrently IE-2 increases IE-1 expression. Western blot analysis indicated that a form of IE-1 copurified with budded virions but did not copurify with the polyhedron-derived virus.