Glycoprotein Vaccine Against IBR

Effect of Vaccination on Latency (Recrudescence After Challenge Exposure)

Abstract

Five cattle were twice vaccinated. The interval between the vaccinations was 28 days.

Five cattle served as non-vaccinated controls. 348 days after the first vaccination, one non-vaccinated control animal was intranasally challenged with 5 .105 TCID50 of virulent BHV1 virus. It served as contact excreter animal for all the other non vaccinated controls and the vaccinates.

After challenge, the following treatments were performed:
- three previously vaccinated animal, and two non-vaccinated controls received one dose of vaccine at day D 390 and day D 411 after challenge while the remaining five animals did not.
- all the animals were treated with dexamethazone during 5 days at day D 455 after challenge (I.V. 1st day, I.M. 4 days).

Vaccination significantly reduced virus excretion and clinical signs after challenge. Some of the vaccinated animals (vaccination before challenge) were protected against recrudescence after dexamethazone treatment.

Detailed results will be presented and discussed in the context of control of BHV1.