Cytopathic effects of Amsacta moorei entomopoxvirus infection on the cytoskeleton of Estigmene acrea cells

Abstract

Virus-induced rounding of cultured Estigmene acrea cells infected with Amsacta moorei entomopoxvirus (AmEPV), observed by phase contrast and scanning electron microscopy, indicated that virus infection resulted in reorganization of the host cell cytoskeleton. Immunofluorescent staining of the tubulin and f-actin components showed a progressive contraction of both the microtubule and microfilament network during the period of AmEPV infection. Microtubules began to depolymerize between 12 and 24 h post-infection (h p.i.) and by 48–72 h p.i., the tubulin had further contracted to form a reduced network around the main cell body, whilst the f-actin became rearranged to form distinct foci and microspikes. During the later stages of infection (96 h p.i.), localization of both tubulin and f-actin could be detected in the area of cytoplasm associated with virus assembly. By 120 h p.i., virus spheroids were detected in the cytoplasm and the tubulin and f-actin were reduced to sparse patches over the cell surface. Depolymerization of the microtubules by colchicine corresponded to the virus-mediated effects, and virus replication was not impeded by colchicine-induced depolymerization. Once virus-induced polymerization of f-actin had occurred to form foci, these remained throughout the period of infection. Treatment of virus-infected cells with aphidicolin and cycloheximide indicated that these effects may be mediated by both early and late virus genes.