Abstract
The cell line Hv-AM1 from Heliothis virescens was characterized for permissiveness and productivity, employing Helicoverpa armigera nucleopolyhedrovirus (HearNPV) and seven other NPVs, including those of Hyphantria cunea (HycuMNPV), Orgyia pseudotsugata (OpMNPV), Bombyx mori (BmNPV), Spodoptera exigua (SeMNPV), Spodoptera litura (SpltMNPV), Lymantria dispar (LdMNPV) and Autographa californica (AcMNPV). Based on budded virus (BV) yields, polyhedrin production, and polyhedra formation, the results showed for the first time that the cell line Hv-AM1 was permissive for HearNPV, HycuMNPV and OpMNPV, supporting moderate levels of BVs, polyhedrin and polyhedra production. Consistent with the previous results, the cell line Hv-AM1 was also shown to be highly permissive for AcMNPV infection, yielding high levels of BVs, polyhedrin and polyhedra. In the cell line Hv-AM1 infected with BmNPV, SpltMNPV and SeMNPV, few, if any, viral progeny were produced, regardless of the severity of the observed cytopathic effects and the significant production of viral DNA, suggesting its semipermissivity nature for these NPVs. In addition, the cell line Hv-AM1 was found to readily undergo apoptosis upon infection with BmNPV, SeMNPV and HycuMNPV, while it was refractive to LdMNPV. Thus, although the cell line Hv-AM1 is not very efficient for HearNPV production, the diverse observed responses and high permissiveness against NPVs indicate that the cell line Hv-AM1 provides a novel system for analyzing the possible mechanisms underlying the permissiveness and productivity of insect cells against NPVs.
