Abstract
The experimental design consisted of a control phase (P) with 5 neonatally thymectomized (TX) and 4 intact control (IC) Holstein-Friesian bull calves exposed to tissue culture media (TCM) at approximately age 9 weeks and a principal phase (P2) with 4 TC and 4 IC calves exposed to bovine viral diarrhea virus (BVDV) at approximately age 9 weeks. Each phase lasted approximately 5 months with P1 during the summer months and P2 during the winter months. A brief treatment regime of antilymphocyte globulin (ALG) followed TX with normal horse globulin used in 2 IC calves and sham TX in 2 IC calves. Immunologic responses to chicken erythrocytes (CRBC), dinitrochlorobenzene (DNCB), tetanus toxoid (TT), Brucella abortus (BA) and Bacillus Calmette-Guerin (BCG) and skin allografts as well as peripheral lymph nodes were evaluated at designated times during each experimental phase following which all calves were necropsied. Although TX was not complete in all calves there was a significant depression of peripheral lymphocyte counts. Lymphoreticular alterations in peripheral lymph nodes suggested an exaggerated humoral response with a lack of the thymic lymphocyte (T-Cell) population and a failure of the primary follicles to mature normally into germinal centers. This lack of maturation, reflecting the failure of memory cells to develop, was not supported by antigenic responses or concentrations of serum immunoglobulin levels. Thymectomy failed to induce significantly different responses by in vitro non-specific mitogen stimulation of lymphocytes in whole blood culture although calves maintained at warm ambient temperatures in P1 demonstrated greater responses to ohytohemagglutinin-P (PHA-P) than those kept at cooler temperatures..
Snider, Theron Gerald (1978). The role of the host immune response in the pathogenesis of bovine viral diarrhea. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -252568.