Serological response in cattle immunized with inactivated oil and Algel adjuvant vaccines against infectious bovine rhinotracheitis.

Infectious bovine rhinotracheitis (IBR) virus was grown in Madin Darby bovine kidney (MDBK) cell line using a roller culture system for its large-scale production. Optimum multiplicity of infection (MOI) of 1:750 was found to give consistent virus yield. To determine the appropriate payload, three batches of antigen with virus titres ranging from 10(8.37) to 10(6.37) TCID50 per ml were used to prepare experimental inactivated IBR oil adjuvant vaccine. Beta-propiolactone (BPL) was used as inactivant. The vaccine formulation using inactivated BHV-1 virus antigen with a pre-inactivation titer of 10(8.37) TCID50 per dose elicited better sero-conversion in cattle calves as evidenced from the mean log SN titre of 1.02. To choose the appropriate adjuvant, two batches of vaccine each containing aluminum hydroxide gel (Algel) and Montanide oil respectively were tested in calves. Two groups of 16 calves each were inoculated with Algel and oil adjuvant vaccine respectively twice at four weeks to test the immunogenicity. Adequate titres of vaccine induced anti BHV-1 antibodies could be demonstrated both by ELISA and MNT up to 180 days post vaccination in both the groups.

Validation of betapropiolactone (BPL) as an inactivant for infectious bovine rhinotracheitis (IBR) virus.

Infectious bovine rhinotracheitis (IBR) virus causes vulvovaginitis, abortion and respiratory disease in cows and heifers. Betapropiolactone (BPL) is a disinfectant, effective against bacteria, fungi and viruses. It is also used to prepare inactivated vaccines because it destroys the nucleic acid core of viruses but does not damage the capsid. For the validation of BPL when used as an inactivant, it is more important to assure the quality of inactivating agent and the validity of the inactivation process. In the present study, the inactivation kinetics of IBR virus was determined with different concentration of BPL (1:250, 1:500, 1:1000, 1:1500, 1:2000 and 1:2500) at 4 and 37 degrees C. The result indicated that the BPL at 4 degrees C was able to inactivate the IBR virus within 4, 5 and 12h with the concentration of 1:250, 1:500 and 1:1000, respectively. BPL at 37 degrees C was able to inactivate virus within 30 min with the concentration of 1:250. BPL with the concentration of 1:500 and 1:1000 were able to inactivate the virus within 120 min at 37 degrees C. Based on the kinetic study seven formulations were prepared and a sero conversion study of IBR inactivated vaccine was carried out. Serological response in animals to different formulations did not differ significantly (P>0.05).