Structure of Broadhaven virus by cryoelectron microscopy: correlation of structural and antigenic properties of Broadhaven virus and bluetongue virus outer capsid proteins.

摘要

BHK cells were inoculated with Broadhaven virus (BRDV), and cells were prepared for cryoelectron microscopy 40 h post-infection. A 3-D reconstruction of BRDV particles was produced, which illustrated the complexity of the structure. Based on sequence homology a comparison of the outer shell proteins of BRDV and bluetongue virus (BTV) showed that apart from 1 protein the shells are very similar. Notable differences were observed in the antigenic properties of the outer capsid proteins of BRDV and BTV. VP5 of BRDV was the major determinant of virus serotype, whereas it had only a minor role in BTV. The cell receptor site was VP4 in BRDV and VP2 in BTV. VP5 in serotype determination was more important in BRDV than in BTV, as the direct result of thestructural differences of the outer capsids and the relative stoichiometry of the outer shell proteins. VP5 was more accessible on the capsid surface of BRDV and present in higher numbers. It is concluded that the role of VP5 in modulating the neurovirulence of Gl subgroup viruses without affecting the ability to replicate cannot be explained through structural studies of BRDV.