Classical swine fever virus: independent induction of protective immunity by two structural glycoproteins.

To study which proteins of classical swine fever virus (CSFV) are able to confer protective immunity in swine, N-terminal autoprotease, viral core protein, and the three structural glycoproteins were expressed via vaccinia virus recombinants (VVR). CSFV proteins synthesized in cells infected with VVR showed migration characteristics on sodium dodecyl sulfate gels identical to those of their respective CSFV counterparts. Apparently authentic dimerization of the recombinant glycoproteins was observed. The glycoproteins E0 and E2 were detected on the surfaces of VVR-infected cells. In protection experiments, swine were immunized with the different VVR, and the generation of humoral immune response was monitored. Only animals vaccinated with VVR expressing E0 and/or E2 resisted a lethal challenge infection with CSFV. Glycoprotein E0 represents a second determinant for the induction of protective immunity against classical swine fever.