Immunologic responses of beef calves to concurrent application of modified-live viral vaccine (intranasal and systemic administration) and systemically administered Mannheimia haemolytica bacterin-leukotoxoid.

Abstract

A study was conducted to assess the immunological response to a Mannheimia haemolytica bacterin-leukotoxoid, given separately or concurrently with a multivalent intranasally administered modified-live viral vaccine to range beef calves. Initially 202 spring-born calves were screened for infectious bovine rhinotracheitis (IBR), bovine respiratory syncytial virus (BRSV), and M. haemolytica leukotoxin antibody titers on day-30. A total of 154 calves with day 0 geometric mean IBR titers of <1:6 were accepted into the study. Fifty-one calves were assigned to treatment group T1 (M. haemolytica bacterin-leukotoxoid only; One Shot®, Pfizer Animal Health, New York, NY) and 51 calves were assigned to group T2 (intranasal modified-live virus (MLV) bovine herpesvirus-1 (BHV-1) and parainfluenza-3 (PI3) vaccine; TSV-2®, Pfizer Animal Health) and M. haemolytica bacterin-leukotoxoid (One Shot®). Fifty-two calves were assigned to group T3 intranasal MLV BHV-1, PI3, and BRSV vaccine (INFORCE^TM 3, Pfizer Animal Health) and M. haemolytica bacterin-leukotoxoid (One Shot®). On day 0, all study calves were administered their assigned vaccine. On day 91, all calves in the study were administered a pentavalent MLV vaccine containing BHV-1, BVD types 1 and 2, BRSV, and PI3 antigens (Bovi-Shield GOLD® 5, Pfizer Animal Health) and M. haemolytica bacterin-leukotoxoid (One Shot®) at separate injection sites. On days 0, 14, 28, 91, and 112, blood samples were collected, serum separated, and held frozen until completion of the study, at which time samples were evaluated for IBR and BRSV serum neutralization antibody titers and M. haemolytica leukotoxin antibody concentrations. Results demonstrated concurrent administration of the intranasal vaccines and the M. haemolytica bacterin-leukotoxoid did not affect the bacterin-leukotoxoid serological response. Calves vaccinated with intranasal BRSV vaccine had a significant (P less than 0.05) increase in BRSV antibody response when revaccinated systemically with injectable 5-way MLV vaccine 90 days later. Vaccination with M. haemolytica bacterin-leukotoxoid at approximately eight weeks of age resulted in a statistically significant (P less than 0.05) anamnestic response following revaccination 90 days later.