OVEREXPRESSION OF ACTIN IN ACMNPV-INFECTED CELLS INTERFERES WITH POLYHEDRIN SYNTHESIS AND POLYHEDRA FORMATION

Autographa californica M nuclear polyhedrosis virus (AcMNPV) terminate s host protein synthesis during the late stage of infection, at approx imately 14 hr postinjection (hpi). If infection takes place in the pre sence of cytochalasin D (CD), however, host actin synthesis is transie ntly stimulated and continues to be synthesized until approximately 30 hpi, and the hyperexpression of polyhedrin is delayed from about 20 h pi until about 36 hpi (S. N. Talhouk and L. E. Volkman, Virology 182, 626-634, 1991; N. Wei and L. E. Volkman, Virology 191, 42-48, 1992). T o investigate whether these events are causally related, i.e., whether actin synthesis negatively affects polyhedrin synthesis, we construct ed recombinant viruses that expressed actin al various levels during i nfection. We found that the expression of actin by a strong promoter i nterfered with polyhedrin synthesis at a posttranscriptional level. It also interfered with polyhedra formation, which may suggest a mechani sm for the observed paucity of polyhedra in infected midgut columnar e pithelial cells in vivo. (C) 1996 Academic Press, Inc.