Propagation and Modification of Infectious Bovine Rhinotracheitis (IBR) Virus in Porcine Kidney Tissue Culture

1. IBR virus was isolated in porcine kidney tissue culture from infected respiratory tissues of cattle, and produced a typical CPE on these cells. The virus was maintained for 10 passages and, when inoculated intranasally into susceptible cattle, produced signs of illness characteristic of IBR. 2. IBR virus passed previously through 7 passages in BKTC could be successfully propagated in PKTC in 2 separate attempts, and was passed 60 times (P-60) and 100 times (RP-100), respectively, in PKTC. 3. Inoculation of P-60 and RP-100 did not cause disease when inoculated either intranasally or intramuscularly into susceptible animals. Intramuscular inoculation of these viruses resulted in a specific antibody response.