Comparison of bovine herpesvirus 1 vaccines for rapid induction of immunity

The purpose of the study reported here was to compare four different vaccine regimens for their efficacy in protecting calves from challenge with bovine herpesvirus 1 (BHV1) at 5 and 14 days after vaccination. Nine experimental groups of five calves each were used to compare four vaccination regimens and a group that received no vaccine. The four vaccine regimens were: a BHV1 intramuscular (IM) vaccine containing both modified live virus (MLV) and killed virus (KV); an MLV intranasal (IN) vaccine; concurrent administration of MLV IN vaccine and MLV IM vaccine; and concurrent administration of MLV IN vaccine and KV vaccine. All vaccine regimens induced solid protection against BHV1 challenge at 14 days after vaccination. All of the vaccine regimens also induced statistically significant (P < .05) protective immunity at 5 days after vaccination; however, there were significant differences (P < .05) in the degree of protection. The best protection induced by 5 days after vaccination was provided by the MLV + KV combination vaccine injected IM and the MLV vaccines given IN and IM concurrently. The MLV + KV combination vaccine administered IM gave significantly (P < .05) better protection by 5 days after vaccination than the MLV vaccine administered IN. Administering a KV BHV1 vaccine IM at the same time as the MLV BHV1 IN vaccine significantly (P < .05) reduced the effectiveness of the IN vaccine for inducing early protective immunity.