Search Results

You are looking at 1 - 6 of 6 items for :

  • Author or Editor: James A. Roth x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To determine the efficacy of a modified-live virus vaccine containing bovine herpes virus 1 (BHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza virus 3, and bovine viral diarrhea virus (BVDV) types 1 and 2 to induce neutralizing antibodies and cell-mediated immunity in naïve cattle and protect against BHV-1 challenge.

Animals—17 calves.

Procedures—8 calves were mock-vaccinated with saline (0.9% NaCl) solution (control calves), and 9 calves were vaccinated at 15 to 16 weeks of age. All calves were challenged with BHV-1 25 weeks after vaccination. Neutralizing antibodies and T-cell responsiveness were tested on the day of vaccination and periodically after vaccination and BHV-1 challenge. Specific T-cell responses were evaluated by comparing CD25 upregulation and intracellular interferon-γ expression by 5-color flow cytometry. Titration of BHV-1 in nasal secretions was performed daily after challenge.

Results—Vaccinated calves seroconverted by week 4 after vaccination. Antigen-specific cell-mediated immune responses, by CD25 expression index, were significantly higher in vaccinated calves than control calves. Compared with control calves, antigen-specific interferon-γ expression was significantly higher in calves during weeks 4 to 8 after vaccination, declining by week 24. After BHV-1 challenge, both neutralizing antibodies and T-cell responses of vaccinated calves had anamnestic responses to BHV-1. Vaccinated calves shed virus in nasal secretions at significantly lower titers for a shorter period and had significantly lower rectal temperatures than control calves.

Conclusion and Clinical Relevance—A single dose of vaccine effectively induced humoral and cellular immune responses against BHV-1, BRSV, and BVDV types 1 and 2 and protected calves after BHV-1 challenge for 6 months after vaccination.

Full access
in American Journal of Veterinary Research

SUMMARY

Previous studies of the amino acid analogue, α-ketoisocaproate (kjc), indicate that it can stimulate lymphocyte blastogenesis and antibody responses of sheep. To determine whether kic could overcome the effects of adrenocorticotropic hormone (acth)-induced lymphocyte suppression, 24 lambs were fed a control diet, a diet supplemented with 0.05% kic, or a diet supplemented with 0.05% of the parent amino acid leucine. Immune status was monitored by determining lymphocyte blastogenic responsiveness to phytohemagglutinin-P (pha), concanavalin A (conA), and pokeweed mitogen (pwm) and percentages of T-cell subsets in the blood, using monoclonal antibodies and a flow cytometer. Serum Cortisol, insulin, and glucagon concentrations also were determined. After 60 days of consuming the respective diet, lambs were administered either saline solution or acth (100 IU) twice daily for 3 consecutive days. Administration of acth increased serum cortisol and insulin concentrations; however, no effects were seen for serum glucagon concentration. Compared with saline administration, acth administration significantly (P < 0.05) suppressed mitogen-stimulated lymphocyte blastogenesis by approximately 50%, regardless of the mitogen used, and significantly (P < 0.01) decreased the percentage of circulating T lymphocytes and decreased (P < 0.01) the ratio of T4 to T8 cells. Lambs fed kic had greater pha- and conA-stimulated blastogenic responses and significantly (P < 0.05) increased ratio of T4 to T8 cells in the blood, compared with lambs fed the leucine-supplemented diet or the control diet and given corresponding injections. These data indicate that acth decreased in vitro lymphocyte blastogenesis and altered the subset ratios of blood lymphocytes in sheep. These changes were partially prevented by feeding kic.

Free access
in American Journal of Veterinary Research

SUMMARY

Cattle persistently infected with bovine viral diarrhea (bvd) virus have decreased neutrophil and lymphocyte functions. We reevaluated these functions and further characterized the inhibition of persistent bvd virus infection in neutrophils, using sensitive kinetic assays. In addition, the influence of in vitro incubation of neutrophils with recombinant bovine interferon gamma (rBoifn gamma) and in vitro incubation of lymphocytes with recombinant bovine interleukin-2 was evaluated.

Significant (P < 0.05) decrease in random migration under agarose, Staphylococcus aureus ingestion, cytochrome-C reduction, iodination, antibody-independent cell-mediated cytotoxicity, oxidant production, and cytoplasmic calcium flux were observed in neutrophils from cattle persistently infected with bvd virus, compared with noninfected control cattle. Incubation of neutrophils from noninfected controls with rBoifn gamma significantly (P < 0.05) decreased random migration under agarose, cytochrome-C reduction, and cytoplasmic calcium flux. Neutrophils from cattle persistently infected with bvd virus also had decreased random migration under agarose after incubation with rBoifn gamma; in addition, antibody-independent cell-mediated cytotoxicity, elastase release, and cytoplasmic calcium flux were significantly enhanced. The rBoifn gamma induced significantly (P < 0.05) different effects on chemotaxis, cytochrome-C reduction, iodination, and cytoplasmic calcium flux of neutrophils from infected and control cattle. The rBoifn gamma was more effective at improving the function of neutrophils from cattle persistently infected with bvd virus, compared with neutrophils from controls.

Lymphocytes from infected cattle had decreased histogenesis in response to phytohemagglutinin, concanavalin A, and pokeweed mitogen. Incubation of those lymphocytes with recombinant bovine interleukin-2, with no mitogen present, significantly (P < 0.05) increased incorporation of [3H]thymidine. However, the response of lymphocytes to mitogen stimulation was not significantly increased by the presence of recombinant bovine interleukin-2, indicating that depression of in vitro lymphocyte histogenesis in the cattle persistently infected with bvd virus is not attributable to decreased production of interleukin-2.

Free access
in American Journal of Veterinary Research

Summary

The influence of recombinant bovine interferon gamma (rBoIFN-gamma) treatment on resistance of clinically normal and dexamethasone-treated calves to Haemophilus somnus infection was evaluated. Four groups of 6 calves each were treated with saline solution (controls), dexamethasone (0.04 mg/kg of body weight/for 3 days), rBoIFN-gamma (2 μg/kg for 2 days), or dexamethasone and rBoIFN-gamma (aforementioned dosages). All treatments were started 24 hours before intrabronchial challenge exposure with 5 × 109 colony-forming units of H somnus. Rectal temperature and WBC count were monitored daily. Two of the dexamethasone-treated calves died of pneumonia 4 days after challenge exposure and were necropsied. All other calves were euthanatized and necropsied 7 days after challenge exposure. All calves had pneumonia of variable intensity. Dexamethasone-treated calves had increased volume of pneumonic lung (P < 0.05) and increased severity of pneumonia, compared with control calves. Recombinant bovine interferon gamma treatment resulted in reduction in pneumonic lung volume and severity of pneumonia in dexamethasone-treated calves (P < 0.05), although it did not influence severity of pneumonia in nondexamethasone-treated calves.

Free access
in American Journal of Veterinary Research

SUMMARY

Recombinant human interleukin-2 (rhil-2) was evaluated for its influence on total and differential wbc counts, lymphocyte blastogenic responsiveness to mitogens, and several measurements of neutrophil function in clinically normal and in dexamethasone-treated cattle. A single dose of rhil-2 (2.5 × 107 U) given sc had no influence on the total or differential wbc count; however, it did cause an inhibition of neutrophil random migration. The other measurements of neutrophil function (Staphylococcus aureus ingestion, cytochrome C reduction, iodination, and antibody-dependent and antibody-independent cell-mediated cytotoxicity) evaluated were not significantly altered. The rhil-2 treatment was associated with a significant (P < 0.01) decrease in uptake of [3H]thymidine in unstimulated lymphocytes and a tendency toward enhanced blastogenesis of lymphocytes stimulated with phytohemagglutinin. This enhancement was significant (P < 0.05) only when the results were expressed as a stimulation index. Lymphocyte responsiveness to concanavalin A and pokeweed mitogen was not significantly influenced by rhil-2 administration. Dexamethasone (0.04 mg/kg) administered every 24 hours for 3 consecutive days altered the wbc count and several measurements of lymphocyte and neutrophil function. The administration of a single dose of rhil-2 (2.5 × 107 U) 8 hours after the first dose of dexamethasone did not alter the influence of dexamethasone on any of the measurements. These results indicated that rhil-2 has some biologic activity in cattle, but when used as administered here, did not overcome the influence of dexamethasone on the in vitro measurements of lymphocyte and neutrophil function that were evaluated.

Free access
in American Journal of Veterinary Research

SUMMARY

The growth hormone (gh) secretagogue activity of variable dosages of clonidine (16.5, 50, 150, and 450 μg/kg of body weight), given orally mixed with the daily food ration, was evaluated in young and old dogs. Significant (P < 0.05) increase in plasma gh concentration was detected at all dosages tested in young dogs and in response to all but the lowest dose tested in the old dogs fed the clonidine-containing diet. Old dogs had plasma gh concentration that exceeded that of young dogs when higher doses of clonidine were used.

A clonidine (100 μg/kg)-supplemented diet was fed to middle-aged dogs twice daily for 30 days. Significant (P < 0.01) increase of plasma gh concentration was observed on the first day of the feeding trial, but was undetectable by day 30. After feeding the clonidine-enhanced diet for 30 days, the effects on thymic morphology were variable, and there was no effect on plasma thymulin titer. Clonidine-fed dogs had significantly increased lymphocyte blastogenic responsiveness to mitogens, compared with that of control dogs, when evaluated as stimulation index.

Free access
in American Journal of Veterinary Research