Characterization of protection against systemic infection and disease from experimental bovine viral diarrhea virus type 2 infection by use of a modified-live noncytopathic type 1 vaccine in calves.
OBJECTIVE
To evaluate protection resulting from use of a modified-live noncytopathic bovine viral diarrhea virus (BVDV) type 1 vaccine against systemic infection and clinical disease in calves challenged with type 2 BVDV.


METHODS
10 calves, 5 to 7 months of age.


METHODS
Calves were allocated (n = 5/group) to be nonvaccinated or vaccinated SC on day 0 with BVDV 1 (WRL strain). Calves in both groups were challenged intranasally with BVDV type 2 isolate 890 on day 21. Rectal temperatures and clinical signs of disease were recorded daily, and total and differential WBC and platelet counts were performed. Histologic examinations and immunohistochemical analyses to detect lesions and distribution of viral antigens, respectively, were performed.


RESULTS
After challenge exposure to BVDV type 2, nonvaccinated calves developed high rectal temperatures, increased respiratory rates, viremia, leukopenia, lymphopenia, and infection of the thymus. Vaccinated calves did not develop high rectal temperatures or clinical signs of respiratory tract disease. Vaccinated calves appeared to be protected against systemic replication of virus in that they did not develop leukopenia, lymphopenia, viremia, or infection of target organs, and infectious virus was not detected in peripheral blood mononuclear cells or the thymus.


CONCLUSIONS
The modified-live BVDV type 1 vaccine protected against systemic infection and disease after experimental challenge exposure with BVDV type 2. The vaccine protected calves against infection and viremia and prevented infection of target lymphoid cells.
Kelling
Clayton L
CL
Department of Veterinary and Biomedical Sciences, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE 68583-0905, USA.
Hunsaker
Breck D
BD
Steffen
David J
DJ
Topliff
Christina L
CL
Eskridge
Kent M
KM
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000940:Antigenic Variation; D001831:Body Temperature; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D002417:Cattle; D003429:Cross Reactions; D030241:Diarrhea Virus 1, Bovine Viral / Q000276:immunology*; D030242:Diarrhea Virus 2, Bovine Viral / Q000276:immunology*; D007150:Immunohistochemistry / Q000662:veterinary; D009297:Nasal Mucosa / Q000821:virology; D009500:Neutralization Tests / Q000662:veterinary; D013950:Thymus Gland / Q000821:virology; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000276:immunology / Q000627:therapeutic use; D014765:Viral Vaccines / Q000276:immunology* / Q000627:therapeutic use*; D014766:Viremia / Q000276:immunology / Q000821:virology; D017201:Virus Shedding / Q000276:immunology
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines