New cell lines derived from the black cutworm, Agrotis ipsilon, that support replication of the A. ipsilon multiple nucleopolyhedrovirus and several group I nucleopolyhedroviruses

Abstract

New cell lines were recently developed from the embryos of the black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae). A primary culture was initiated from 4-day-old A. ipsilon eggs in ExCell420 medium supplemented with 5% fetal bovine serum. This initial culture produced sufficient cell growth to allow subcultivation and eventually led to the establishment of eight distinct strains. Two of these strains (AiE1611T and AiEd6T) were selected for further characterization. Extracts of these strains were compared to an extract from A. ipsilon eggs by isozyme analysis and shown to be from the same species. Both strains were susceptible to infection by the A. ipsilon multiple nucleopolyhedrovirus (AgipMNPV), as well as to lepidopteran group I NPVs from A. californica, Anagrapha falcifera, Anticarsia gemmatalis, Galleria mellonella, Helicoverpa armigera, Plutella xylostella, and Rachiplusia ou, with large numbers of occlusion bodies produced in most of the inoculated cells. The cell lines did not support the replication of group II NPVs from Helicoverpa zea, Lymantria dispar, and Spodoptera exigua. Both cell lines produced confluent monolayers in plaque assays and supported the formation of plaques upon infection with AgipMNPV and Autographa californica (Ac)MNPV. Twenty AgipMNPV plaques were picked from either AiE1611T or AiEd6T monolayers, and the plaque isolates were serially passaged three times through A. ipsilon cells. Only one isolate from AiE1611T cells exhibited genotypic variation in the form of an altered restriction fragment profile. Our results suggest these new lines can be useful in the study of AgipMNPV and A. ipsilon cellular and molecular biology.