Evaluation of experimental subunit vaccines for infectious bovine rhinotracheitis.

Subunit infectious bovine rhinotracheitis (IBR) antigens were prepared by solubilization of IBR-virus infected cell cultures with nonionic detergents Triton X-100 and NP-40. When used with Freund's incomplete adjuvant, Triton X-100 and NP-40 subunit antigens induced high serum-neutralization titers in vaccinated calves. Two doses of Triton X-100 and NP-40 subunit vaccines prevented the appearance of clinical signs of disease in all vaccinated calves exposed 30 days after the second vaccinal dose to intranasal challenge exposure with Cooper strain of IBR virus. Furthermore, two doses of NP-40 subunit vaccine prevented shedding of the virus in all vaccinated calves after challenge exposure.