Characterization of protection from systemic infection and disease by use of a modified-live noncytopathic bovine viral diarrhea virus type 1 vaccine in experimentally infected calves.
OBJECTIVE
To evaluate protection against systemic infection and clinical disease provided by use of a modified-live noncytopathic bovine viral diarrhea virus (BVDV) type 1 vaccine in calves challenged with NY-1 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 type 1 (WRL strain). Calves in both groups were challenged intranasally with NY-1 BVDV on day 21. Calves' rectal temperatures and clinical signs of disease were recorded daily, total and differential WBC and platelet counts were performed, and serum neutralizing antibody titers against NY-1 BVDV were determined. Histologic examinations and immunohistochemical analyses to detect gross lesions and distribution of viral antigens, respectively, were performed.


RESULTS
After challenge exposure to NY-1 BVDV, 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 vaccine protected calves against systemic infection and disease after experimental challenge exposure with NY-1 BVDV. 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
Abdelmagid
Omar Y
OY
Eskridge
Kent M
KM
D000704:Analysis of Variance; D000818:Animals; D001772:Blood Cell Count; D001831:Body Temperature; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000517:prevention & control*; D002417:Cattle; D030241:Diarrhea Virus 1, Bovine Viral / Q000276:immunology* / Q000302:isolation & purification; D007150:Immunohistochemistry; D009500:Neutralization Tests; D013950:Thymus Gland / Q000821:virology; D014765:Viral Vaccines / Q000276:immunology*; D014766:Viremia / Q000517:prevention & control / Q000662:veterinary; D017201:Virus Shedding
D014765:Viral Vaccines