Inactivation of infectious bovine rhinotracheitis virus by gamma irradiation

Radiation inactivation of Infectious Boivne Rhinotracheitis (IBR) virus was investigated by suspending in a commercial preparation medium (c.p.m.) or IBR antibody free serum and irradiated at room temperature or dry ice frozen condition. Normal pooled serum was also analysed by electrophoresis with cellulose acetate membrane after irradiation at frozen and non-frozen condition. The virus inactivation was determined by MDBK cell line which 50 % tissue culture infectious dose (TCID50) was calculated by Behrens Kaerber method. D10 value at non-frozen condition in serum was obtained as 1.1-1.2 kGy and that in c.p.m. was 1.3-1.4 kGy. On the other hand, D10 value was increased to 3.4-3.6 kGy in serum and 3.9 kGy in c.p.m. at frozen condition. On the irradiation effect of bovine serum, four peaks of albumin, α, β and γ-globulin fraction were obtained from non-irradiation and irradiated serum up to 2 kGy at non-frozen condition by electrophoresis. More than 4 kGy irradiation, the peaks of globulin fractions became not clear and at more than 8 kGy, changed to one large peak. On the other hand, these changes of electrophoretic patterns were not observed even at 30 kGy irradiation in frozen condition. From these results, necessary dose was decided as 20-25 kGy at frozen condition for inactivation of IBR virus in serum. (author)