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

Objective: The occlusion-derived form of baculovirus is specially adapted for primary infection of host midgut epithelial cells. The virion contains proteins essential for host-range determination and initiation of infection. Determination of protein composition of the occlusion-derived virus (ODV) will help us to understand this virion's infection mechanism. Methods: We obtained the ODV virion of Bombyx mori nucleopolyhedrovirus (BmNPV) by sucrose density gradient centrifugation, and used SDS-PAGE, 2-dimensional electrophoresis and mass spectrometry to identify-for the first time-proteins present within or associated with the ODV virion. Results: 20 proteins, including 16 major proteins of the virion encoded by BmNPV and 4 proteins of the silkworm, were identified with confidence. Conclusion: Three BmNPV proteins (orf40, P95 and protein tyrosine phosphatase), which had not been detected as components of ODV previously, were identified in this study. We propose that the host-derived proteins may be important for the assembly and maturation of the ODV capsid. Copyright (C) 2009 S. Karger AG, Basel