Replication of nucleopolyhedroviruses of Autographa californica (Lepidoptera : Noctuidae), Bombyx mori (Lepidoptera : Bombycidae), Hyphantria cunea (Lepidoptera : Arctiidae), and Spodoptera exigua (Lepidoptera : Noctuidae) in four lepidopteran cell lines

Four different NPV isolates from Autographa californica (AcNPV), Bombyx mor i (BmNPV), Hyphantria cunea (HcNPV) and Spodoptera exigua (SeNPV) were char acterized for their biological properties in four lepidopteran cell lines w hich were derived from S. frugiperda (IPLB-Sf-21), B. mori (BmN-4), Spiloso ma imparilis (FRI-SpIm-1229), and S. exigua (Se301). On the basis of the da ta on viral DNA replication, viral structural protein synthesis, budded vir ion (BV) yield, polyhedrin synthesis, and polyhedral formation in the infec ted cells, it was demonstrated that each of these NPV isolates established specific interactions with the respective cell lines. Of 16 NPV-cell system s examined, three NPV-cell systems exhibited two different types of abortiv e infection. In HcNPV-infected BmN-4 cells, viral DNA replication occurred but the infection aborted at the step prior to late gene expression, wherea s both AcNPV-infected BmN-4 cells and HcNPV-infected IPLB-Sf-21 cells yield ed BVs into culture medium but were defective in polyhedrin expression. In addition, it was found that SeNPV exhibited a unique infection process in F RI-SpIm-1229 cell cultures, in which viral DNA replicated and a limited num ber of polyhedra were formed in a restricted number of infected cells while few, if any, progeny BVs were produced and a significant proportion of inf ected cells displayed apoptotic-like morphology. The present study, thus, d eveloped various NPV-cell systems which facilitate the analysis of molecula r mechanisms underlying baculovirus dhost specificity determination.