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  • Author or Editor: James C. Brown Jr x
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Abstract

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.

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

Procedure—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-γ) 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 VCgroup calves. No difference was seen between distributions of BRSV in lung tissue of VC- and MC-group calves. Production of BRSV-specific IFN-γ was increased in tissue specimens from VC-group calves, compared with MC- and control-group calves. Virusspecific IFN-γ production was highest in the mediastinal lymph node of VC-group calves. Increased numbers of T cells were found in expanded bronchialassociated lymphoid tissue and airway epithelium of VC-group calves.

Conclusions and Clinical Relevance—An intranasal dose of modified-live BRSV vaccine can protect calves against virulent BRSV challenge 1 month later. ( Am J Vet Res 2004;65:363–372)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize cytokine messenger RNA (mRNA) expression in intranasally vaccinated calves after bovine respiratory syncytial virus (BRSV) challenge.

Animals—Twelve 8- to 12-week-old calves.

Procedures—Calves received modified-live BRSV vaccine (vaccinated) or spent tissue culture medium (mock-vaccinated) intranasally, followed by challenge 30 days later with BRSV, or mock challenge with spent tissue culture medium (mock-challenge controls). Interleukin-4 (IL-4) and interferon-γ (IFN-γ) mRNA was measured in lungs, bronchoalveolar lavage (BAL) fluid cells, pharyngeal tonsils, and tracheobronchial lymph nodes, and tumor necrosis factor-α (TNF-α) mRNA was measured in lungs and BAL fluid cells by reverse transcriptase-competitive polymerase chain reaction assay.

Results—Resistance to clinical signs of disease was conferred in vaccinated calves. Expression of TNF-α mRNA in lungs and BAL fluid cells was higher in mock-vaccinated calves than control or vaccinated calves. In the lung, IL-4 mRNA expression was higher in vaccinated calves than control or mock-vaccinated calves. In pharyngeal tonsils, expression of mRNA for IL-4 and IFN-γ was higher in mock-vaccinated calves than control calves. In tracheobronchial lymph nodes, IFN-γ mRNA expression was higher in mock-vaccinated calves than vaccinated calves.

Conclusions and Clinical Relevance—Although vaccinated calves had decreased clinical signs of disease after BRSV challenge, compared with mock-vaccinated calves, this difference was not related to a T helper type 1 bias, as determined by increased expression of interferon-γ mRNA relative to interleukin-4 mRNA in lungs, BAL fluid cells, or tracheobronchial lymph nodes of vaccinated calves. Pulmonary inflammation was decreased in vaccinated calves as determined by decreased expression of TNF-α mRNA. (Am J Vet Res 2004;65:725–733)

Full access
in American Journal of Veterinary Research