Rabbit-adaptive CSFV mutants were detected in rabbit spleens. (A) Indirect immunofluorescence staining of the SK6 cells infected with viruses isolated from the rabbit spleens and the nuclei stained with DAPI. Bar, 400 μm. (B) Viral antigens in the spleen samples detected by immunohistochemistry. The E2 glycoprotein was detected by anti-E2 antibody in the spleen lymphocytes from the rabbits inoculated with HCLV, vSM-HCLVErnsE2DomainI, or vSME2L108P-I109T-HCLVErns but not the Shimen strain, vSM-HCLVErnsE2DomainII, or DMEM. Bar, 50 μm.