Formation of P10 tubular structures during AcMNPV infection depends on the integrity of host-cell microtubules.

During infection of insect cells with Autographa californica nucleopolyhedrovirus (AcMNPV), the very late protein P10 forms large fibrillar structures in the cytoplasm and nuclei of infected cells. In this study we have used confocal microscopy in association with a novel P10 antiserum to localise and study P10 in virus-infected cells. P10 was shown to be a component of tubular-like structures that spiralled throughout the cytoplasm and nucleus of AcMNPV-infected cells. These structures were observed to colocalise partly with cortical microtubules. When microtubules were depolymerised with the drug nocodazole, P10 tubules failed to form and the protein appeared concentrated in cytoplasmic foci. For the first time, we provide direct evidence using both antibody pulldown and yeast two-hybrid experiments for the interaction of P10 with host-cell tubulin. It is suggested that this interaction may be a critical factor in AcMNPV-induced cell lysis.