SPECIFICITY OF BACULOVIRUS P10 FUNCTIONS

Three functional domains in baculovirus p10 proteins have been postula ted for aggregation, nuclear disintegration, and fibrillar structure f ormation (Van Oers er al., J. Gen. Virol. 74, 563-574, 1993). To study the specificity of these functions, a recombinant Autographa californ ica nuclear polyhedrosis virus (AcCR1) was constructed in which the co ding sequence of the p10 gene was replaced with the p10 sequence of th e distantly related Spodoptera exigua (Se) MNPV. In AcCR1-infected cel ls the SeMNPV p10 protein was produced at similarly high levels as AcM NPV pig in wild type (wt) AcMNPV infections. Formation of fibrillar st ructures occurred in a similar fashion in SeMNPV and AcCR1-infected ce lls. Hence, the SeMNPV p10 protein retained the ability to associate i nto fibrillar structures when expressed in an otherwise AcMNPV context . Mixed infection with wt AcMNPV and AcCR1 indicated that only pig pro teins of the same species aggregate and that these aggregates associat e into fibrillar structures. In contrast to S. exigua cells infected w ith AcMNPV or SeMNPV, S. exigua cells infected with AcCR1 failed to re lease polyhedra. This result indicated that interaction of p10 with at least one virus-specific factor is required for nuclear disintegratio n. (C) 1994 Academic Press, Inc.