Host Filamentous Actin Is Associated with Heliothis armigera Single Nucleopolyhedrosis Virus (HaSNPV) Nucleocapsid Transport to the Host Nucleus

Abstract

VP39 is the major capsid protein of Heliothis armigera nucleopolyhedrovirus (HaSNPV), and it might have induced the aggregation of host cellular actin in vitro in our previous study. We demonstrated here that VP39 could interact with host actin in vivo in Helicoverpazea (Hz-AM1 cells) through coimmunoprecipitation assay. With confocal immunofluorescence microscopy, it was confirmed further that the released HaSNPV nucleocapsids/VP39s in the host cytoplasm (0.5 hours after infection) colocalized where the actin aggregated and that the nucleocapsids/VP39s were transported from the host cytoplasm to the nucleus (2 hours after infection). Because cytochalasin D (CD) was used to prevent host global actin from forming filamentous structures, the infection efficiency of the recombinant virus HaSNPV/gfpdeltap74, with the gfp gene inserted into HaSNPV p74 gene loci, was decreased to 7.34%, whereas it was 34.7% in normal host cells and 55.7% in the cells whose microtubules had been destroyed by colchicin. Ultramicroscopy assay revealed that HaSNPV nucleocapsids could enter the cytoplasm of CD-treated cells but could not be transported to the nucleus, which resulted in the lower infection efficiency of HaSNPV/gfpdeltap74 in CD-treated cells. However, transportation of the nucleocapsids was not inhibited in colchicin-treated cells, demonstrating that the transportation of HaSNPV nucleocapsid from the cytoplasm to the nucleus was associated with actin filaments but not with microtubules, a conclusion that is also strongly supported by evidence from the RNAi interference of host actin during HaSNPV infection.

The MERS-CoV N Protein Regulates Host Cytokinesis and Protein Translation via Interaction With EF1A

“…Direct and indirect interactions between viral nucleocapsids and actin have been widely documented and are generally used for intracellular transport of nucleocapsids, which is crucial for viral infection or packaging ( van Loo et al, 2001 ; Xu et al, 2007 ; Schudt et al, 2013 , 2015 ). In this study, abnormal F-actin fibers were observed in cells with N protein expression mediated by plasmid transfection and MERS-CoV infection.…”

Toward system-level understanding of baculovirus–host cell interactions: from molecular fundamental studies to large-scale proteomics approaches

“…Lu et al (2004) observed that Helicoverpa armigera NPV ( Ha NPV) VP39 nucleocapsid protein not only binds to actin, but also promotes its complexation to form actin cables structures, in vitro . In fact, it has been demonstrated that several Ac MNPV nucleocapsid proteins (such as VP39, P78, and VP80) bind to actin directly (Xu et al, 2007; Ohkawa et al, 2010; Marek et al, 2012). …”

Determination of Protein Composition and Host-Derived Proteins of <i>Bombyx mori</i> Nucleopolyhedrovirus by 2-Dimensional Electrophoresis and Mass Spectrometry

“…Transportation of nucleocapsid from the cytoplasm to the nucleus was associated with actin filaments. VP39 may play an important role in the process of transportation of nucleocapsid and assembly of progeny virion [22,23] . GP41/P40, a major glycoprotein not found in BV, has been identified in ODV.…”