THE EFFECT OF HEAT, PH, UREA AND ULTRAVIOLET-LIGHT ON PSEUDORABIES VIRUS GROWTH-FACTOR (PRGF) ACTIVITY

Pseudorabies virus growth factor (PRGF) and its two components PRGF(A) and PRGF(B) were exposed to different temperatures at pH 7.0 and 9.5 either combined with different molarities of urea, or without urea. Th e temperature treatment resulted in enhancing of transforming activity of PRGF, PRGF(A) and PRGF(B) and of the transformation repressing act ivity of PRGF. The titer of all PRGF samples was repeatedly elevated t o constant values (approximately) 10(1)-10(5) times) at each chosen te mperature within a constant time, which could be shortened by high pH or urea. A similar enhancing effect was observed following UV irradiat ion. Detergents and lipid solvents had no effect on PRGF activities. H eparin had no effect upon the transforming activity of non-resolved PR GF; however, it completely destroyed its suppressing effect on transfo rmed phenotype.