A cloned cell line ofSpodopteta exiguahas a highly increased susceptibility to theSpodoptera exiguanuclear polyhedrosis virus

Abstract

A cloned cell line designated Se301, derived from a continuous Se3FH cell line of the beet army worm Spodoptera exigua, showed 10 times greater sensitivity when tested with the plaque assay to a S. exigua nuclear polyhedrosis virus (SeNPV) as compared with the parent cell line. Nearly 100% of Se301 cells were infected with the plaque purified isolate SeNPV-I1 or the wild isolate SeNPV-IW. Plaques were first detected 3–4 days in the Se301 cell line, which was 1–2 days faster than the Se3FH cell line. The size of plaques formed in the Se301 cell line was markedly larger than that of the parental cell line. At 12 h post infection, the production of the extracellular viruses (ECVs) in the Se301 cell line infected with either SeNPV-I1 or SeNPV-IW was 20–40 times greater than that in the Se3FH cell line. In contrast, Se301 cells infected with SeNPV-I1 or SeNPV-IW produced polyhedral inclusion bodies (PIBs) at lower levels compared with Se3FH cells. The isolate SeNPV-I1 consistently produced more ECVs and PIBs in both the Se301 and Se3FH cell lines than the isolate SeNPV-IW.Key words: Spodoptera exigua, nuclear polyhedrosis virus, cloned cell line, increased virus sensitivity, virus production.