Identification of the pseudorabies virus glycoprotein gp50 as a major target of neutralizing antibodies.

A total of 108 monoclonal antibodies specific for pseudorabies virus (PRV) were isolated in a cellular fusion, using spleen cells from mice which had been immunized with a live strain (Kojnok strain). Twelve of them neutralized the Kojnok strain in vitro in the absence of complement, as well as 28 virulent strains of various geographical origin and isolated from various animal species. All of the 12 clones were specific for glycoprotein gp50. Eighteen other clones with no neutralizing activity were studied: 11 reacted with glycoprotein GIII, 3 with glycoprotein GII, 3 with the glycoprotein gp63 and 1 with the glycoprotein GI. Transfer to mice of ascitic fluids corresponding to clones reacting with gp50 and GIII showed that some of them provided the mice with the ability of resisting to virulent challenge. Thus it appears that glycoproteins gp50 and GIII are major immunogens of the virion.