Transmission electron micrographs of the purified fusion proteins. (A) TEM analysis of NvC-aD. (B) NvC-aD probed with anti-HBsAg, followed by protein A conjugated to 5-nm gold particles. The arrows indicate gold particles. (C) NvC probed with anti-HBsAg, followed by protein A conjugated to 5-nm gold particles. The samples were stained negatively with uranyl acetate (1% [wt/vol]) and viewed under ×100,000 magnification.