Effects of a single intranasal dose of modified-live bovine respiratory syncytial virus vaccine on resistance to subsequent viral challenge in calves.
OBJECTIVE
To determine whether a single intranasal dose of modified-live bovine respiratory syncytial virus (BRSV) vaccine protects calves from BRSV challenge and characterize cell-mediated immune response in calves following BRSV challenge.


METHODS
13 conventionally reared 4- to 6-week-old Holstein calves.


METHODS
Calves received intranasal vaccination with modified live BRSV vaccine (VC-group calves; n = 4) or mock vaccine (MC-group calves; 6) 1 month before BRSV challenge; unvaccinated control-group calves (n = 3) underwent mock challenge. Serum virus neutralizing (VN) antibodies were measured on days -30, -14, 0, and 7 relative to BRSV challenge nasal swab specimens were collected for virus isolation on days 0 to 7. At necropsy examination on day 7, tissue specimens were collected for measurement of BRSV-specific interferon gamma (IFN-gamma) production. Tissue distribution of CD3+ T and BLA.36+ B cells was evaluated by use of immunohistochemistry.


RESULTS
The MC-group calves had significantly higher rectal temperatures, respiratory rates, and clinical scores on days 5 to 7 after BRSV challenge than VC-group calves. No difference was seen between distributions of BRSV in lung tissue of VC- and MC-group calves. Production of BRSV-specific IFN-gamma was increased in tissue specimens from VC-group calves, compared with MC- and control-group calves. Virus-specific IFN-gamma production was highest in the mediastinal lymph node of VC-group calves. Increased numbers of T cells were found in expanded bronchial-associated lymphoid tissue and airway epithelium of VC-group calves.


CONCLUSIONS
An intranasal dose of modified-live BRSV vaccine can protect calves against virulent BRSV challenge 1 month later.
Woolums
Amelia R
AR
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
Brown
Corrie C
CC
Brown
James C
JC
Cole
Dana J
DJ
Scott
Melissa A
MA
Williams
Shamita M
SM
Miao
Congrong
C
D000281:Administration, Intranasal; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D007150:Immunohistochemistry; D007371:Interferon-gamma; D018357:Respiratory Syncytial Virus Infections / Q000517:prevention & control* / Q000662:veterinary*; D022261:Respiratory Syncytial Virus Vaccines / Q000008:administration & dosage*; D018112:Respiratory Syncytial Virus, Bovine / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
D000914:Antibodies, Viral; D022261:Respiratory Syncytial Virus Vaccines; D007371:Interferon-gamma