REPLICATION OF ANTICARSIA GEMMATALIS NUCLEAR POLYHEDROSIS-VIRUS IN 4 LEPIDOPTERAN CELL-LINES

Anticarsia gemmatalis nuclear polyhedrosis virus (AgNPV; family Baculo viridae) is pathogenic for larvae of the velvetbean caterpillar, Antic arsia gemmatalis Hubner-an important pest of soybean. AgNPV is a viabl e alternative to chemical control of A gemmatalis in Brazil, where its use as a pesticide has brought significant economic and environmental benefits. Although a significant amount of information is available o n the ecological and biological control aspects of AgNPV, very little is known about the replication cycle and host specificity of this viru s. We examined the susceptibility of four lepidopteran cell lines to A gNPV. Infections of the A. gemmatalis UFL-AG-286 cell line were highly productive. Ninety percent of infected cells had polyhedral inclusion bodies by 48 hr after infection, and the infectious virus titer was 1 0(8) IU/ml. Viral DNA replication was efficient, and the maximal rate of synthesis was between 6 and 12 hr after infection. Infections of th e Spodoptera frugiperda IPLB-SF-21 cell line were productive but less efficient. Infections of Choristoneura fumiferana IPRI-CF-124T cells w ith this virus were poor, with only 5% of the cells forming polyhedra and an infectious virus titer of 10(6) IU/ml. The level of viral DNA r eplication was low. suggesting that this system was predominantly abor tive. Infections of Bombyx mori BM-5 cell lines were abortive, and cel ls had apoptosis-like morphology. No polyhedra or increase in infectio us levels were observed, and there was little or no replication of vir al DNA. Our data suggest that restriction of AgNPV replication in abor tive cell lines is due mainly to inability of viral DNA to replicate e fficiently. The possible causes of low DNA replication are discussed. Our results suggest that the cell lines utilized in this study can pro vide an important model for studying mechanisms of AgNPV host specific ity. (C) 1997 Academic Press.