Distribution of viral antigen and development of lesions after experimental infection with highly virulent bovine viral diarrhea virus type 2 in calves.
OBJECTIVE
To correlate tissue distribution with development of lesions after experimental infection with a virulent strain of noncytopathic bovine viral diarrhea virus (BVDV) type 2 in calves.


METHODS
Ten 14-day-old and two 2-month-old colostrum-deprived calves.


METHODS
Calves were intranasally inoculated with BVDV type-2 strain 1373 from an outbreak of clinically severe bovine viral diarrhea (BVD). Two 14-day-old calves served as noninfected controls. Two calves each were euthanatized on postinoculation days 3, 6, and 12, and 1 each on days 8, 9, 13, and 14. Tissues were collected for immunohistologic and histologic examination.


RESULTS
Inoculated calves developed nonspecific clinical signs characterized by high fever and decreased numbers of leukocytes and thrombocytes. Viral antigen was detected focally in lymphoid tissues on day 3. On days 6, 8, 9, 12, and 14, viral antigen became increasingly widespread throughout organs and tissues. Viral antigen in lymphoid tissues was associated with severe depletion of all compartments. Lesions in other tissues were not well correlated with distribution of viral antigen. Depletion of lymphoid tissues was observed in a calf on day 13, but viral antigen had been cleared from most tissues and was detected in vascular walls only.


CONCLUSIONS
Infection with a virulent BVDV strain resulted in wide dissemination of viral antigen in host tissues. Severe lymphoid depletion developed in lymphoid tissues, whereas viral antigen was generally not associated with lesions in other tissues. Findings suggest that development of lesions in acute BVD is not solely a function of viral replication and is also attributable to host reaction to infection.
Liebler-Tenorio
Elisabeth M
EM
Department of Pathology, Veterinary School Hannover, Germany.
Ridpath
Julia E
JE
Neill
John D
JD
D000818:Animals; D000956:Antigens, Viral / Q000378:metabolism*; D001831:Body Temperature / Q000502:physiology; D001853:Bone Marrow / Q000821:virology; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D002417:Cattle; D001908:Diarrhea Viruses, Bovine Viral / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D007150:Immunohistochemistry / Q000662:veterinary; D007422:Intestines / Q000473:pathology / Q000821:virology; D007958:Leukocyte Count / Q000662:veterinary; D018655:Lymphocyte Count; D008221:Lymphoid Tissue / Q000473:pathology / Q000821:virology
D000956:Antigens, Viral