Pseudorabies virus (PRV) growth factor (PRGF) which induces a transfor
med phenotype in normal MK-2 cells and represses the transformed pheno
type of Hela cells was partially purified and resolved into two compon
ents (M(r)<300 and <180). Each of the PRGF components retained the tra
nsforming activity of the original factor in MK-2 cells but lost its t
ransformation-repressing activity in Hela cells. The latter activity o
f PRGF could be reconstituted by simultaneous application of its two c
omponents. Two monoclonal antibodies against gII glycoprotein of PRV w
ere able to neutralize both PRGF activities, thus supporting the previ
ously suggested hypothesis that the PRV gene for glycoprotein gII migh
t be involved in PRGF synthesis.