Serologic response to Mannheimia haemolytica in calves concurrently inoculated with inactivated or modified-live preparations of M. haemolytica and viral combination vaccines containing modified-live bovine herpesvirus type 1.
OBJECTIVE
To assess the serologic response of calves to inactivated and modified-live (ML) Mannheimia haemolytica (MH) preparations given alone and concurrently with combination viral vaccines containing ML bovine herpesvirus type 1 (BHV-1).


METHODS
642 calves seronegative for BHV-1.


METHODS
In experiment 1, 192 calves received 1 of 3 MH preparations alone or concurrently received 1 of 3 MH preparations and 1 of 4 combination viral vaccines. In experiment 2, 450 calves received 1 of 4 MH preparations alone or concurrently received 1 of 4 MH preparations and 1 of 5 combination viral vaccines. Pretreatment and posttreatment blood samples were processed to obtain serum, which was analyzed to detect concentrations of antibodies against MH leukotoxin and BHV-1.


RESULTS
In experiment 1, antibody titers against MH leukotoxin in calves receiving MH and ML virus vaccine appeared decreased, albeit nonsignificantly, compared with titers for calves receiving MH preparations alone. In experiment 2, all groups (except for 1) concurrently receiving an MH preparation and viral vaccine had a significant decrease in antibodies against MH leukotoxin. In both experiments, there was a significant decrease in the number of calves responding to MH leukotoxin when ML viral vaccine was coadministered.


CONCLUSIONS
Coadministration of ML BHV-1 and MH preparations interfered with the serologic response to MH leukotoxin in calves seronegative for BHV-1. Serologic response to MH leukotoxin may be substantially improved in seronegative calves when MH vaccination is delayed until after calves have received a dose of ML BHV-1 vaccine.
Pfizer Animal Health, Pfizer Incorporated, 685 3rd Ave, New York, NY 10017, USA. victor.cortese@pfizer.com
Victor S
VS
Cortese
Jon T
JT
Seeger
Gerald S
GS
Stokka
Breck D
BD
Hunsaker
Gregory P
GP
Lardy
Daniel J
DJ
Weigel
Gordon W
GW
Brumbaugh
D000367:Age Factors; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood; D001427:Bacterial Toxins / Q000276:immunology; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology; D002417:Cattle / Q000276:immunology*; D002418:Cattle Diseases / Q000276:immunology / Q000517:prevention & control*; D005098:Exotoxins / Q000276:immunology; D005260:Female; D007242:Herpesvirus 1, Bovine / Q000276:immunology; D007114:Immunization / Q000662:veterinary; D008297:Male; D016978:Mannheimia haemolytica / Q000276:immunology; D011897:Random Allocation; D012141:Respiratory Tract Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000276:immunology; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000276:immunology
D000907:Antibodies, Bacterial; D000914:Antibodies, Viral; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D005098:Exotoxins; D017778:Vaccines, Combined; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; C018579:leukotoxin