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SUMMARY

Six monoclonal antibodies (mab) to virulent Mycobacterium bovis ATCC 19210 were produced, using a suspension of heat-inactivated whole cells. Immunoglobulin isotype for mab VMB6, VMB73, and VMB93 was IgG1, and for VMB31, VMB99, and VMB119, it was IgG2a. Monoclonal antibodies were examined for cross-reactivity to M tuberculosis, M kansasii, M fortuitum, M paratuberculosis, M avium serovars 1, 2, 4, 8, and 10, M chelonei, M phlei, M scrofulaceum, M smegmatis, Nocardia asteroides, and Rhodococcus equi. Monoclonal antibodies could be grouped on the basis of binding activity by elisa and immunoblot analysis, in which mab VMB6, VMB31, and VMB119 had binding activity to M bovis; mab VMB93 and VMB99 detected M bovis and M tuberculosis antigens, and mab VMB73 reacted with other mycobacterial species, as well as with N asteroides and R equi. Apparent molecular mass of antigens was 30 to 25 kilodaltons (kD) for VMB6, VMB31, and VMB119 and 63 kD for VMB93 and VMB99, and ranged from > 200 to 31 kD for VMB73, as estimated by immunoblot analysis. Monoclonal antibody binding activity to 18 field isolates of M bovis was evaluated, using elisa. Each of 18 field isolates was detected, using mab VMB6, VMB31, or VMB119; 10 isolates were detected, using mab VMB93/VMB99, and 14 were detected by use of mab VMB73. Use of mab in elisa failed to detect antigens from M bovis strain AN-5.

Free access
in American Journal of Veterinary Research

Summary

The effects of alkalinizing agents, administered prior to feeding colostrum, on blood-gas and acid-base values and on absorption of IgGl were determined in 40 newborn Holstein calves. Two treatments, sodium bicarbonate (3 mEq/kg of body weight, IV) and doxapram HCl (2 mg/kg, IV), were evaluated, using a randomized complete-block experimental design. These treatments resulted in significant (P< 0.01) alteration of blood-gas and acid-base values, generally in the direction of normal values for adult cattle. Significant least squares mean effects were detected for sodium bicarbonate treatment on blood pH ( + 0.04 units, P < 0.01), Pco2( + 4.1 mm of Hg, P <0.01), and HCO3 concentration ( + 4.4 mEq/L, P < 0.01). Significant least squares mean effects were detected for doxapram HC1 treatment on blood pH ( + 0.06 pH units, P <0.01) and Pco2(–5.2 mm of Hg, P <0.01). Absorption of colostral IgGl was not affected by the treatments given or by the altered blood-gas and/or acid-base status.

Free access
in American Journal of Veterinary Research

SUMMARY

To investigate the influence of humoral immunity on the severity of disease caused by infection with bovine respiratory syncytial virus (brsv), an experimentally induced infection study was performed on vaccinated and nonvaccinated calves. Fifteen weanling calves were allotted to 3 groups: 1 group of 6 calves was exposed to 2 live virus aerosols, 35 days apart; another group of 6 calves was vaccinated prior to the same aerosol exposures; and the remaining 3 calves served as controls. Clinical signs of infection were converted to a numerical score for evaluating disease severity. For 14 days after each virus exposure, brsv-specific IgG and IgM concentrations in serum and BRSV-specific IgA concentration in nasopharyngeal exudate and lung lavage fluid were measured by elisa. Serum brsv-specific IgG and IgM and secretory brsv- specific IgA concentrations did not correlate with disease sign expression. There was a strong correlation between viral isolation and disease scores. Vaccination prior to virus exposure appeared to have little or no effect on severity of the disease, but it did appear to affect disease persistence. Findings indicate that the immunoglobulins evaluated may be primarily protective in nature and do not contribute to disease severity.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine optimal zinc sulfate test solution concentration tor detecting failure ot passive transfer in calves.

Animals

235 calves (1 to 8 days old) from a calf-rearing operation in central Washington state.

Procedure

Zinc sulfate turbidity tests, using 200-, 250-, 300-, 350-, and 400-mg/L test solutions, were performed on calf serum. These increasing concentrations were evaluated for detection of failure of passive transfer Using 1,000 mg of IgG,/dl as the threshold for adequate passive transfer, sensitivity, specificity, and accuracy of classification were determined by comparing the zinc sulfate test results with serum IgG, concentration (mg/dl) measured by radial immunodiffusion.

Results

The 200-mg/L zinc sulfate turbidity test solution was 100% sensitive; however, specificity was only 25 5% Increasing concentrations of zinc sulfate test solution up to 350 mg/L improved specificity with either no change or small decreases in sensitivity.

Conclusion and Clinical Relevance

The endpoint of the traditional 208-mg/L zinc sulfate turbidity test for failure of passive transfer in calves is too high. Increased test solution concentrations improve specificity with only minor adverse effects on sensitivity. (Am J Vet Res 1996;57:1711–1713)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To investigate whether the procedure used to snare and restrain pigs during collection of blood samples would alter in vitro functional capacity of leukocytes in the samples.

Animals

8 gilts.

Procedure

Catheters were surgically inserted into the jugular vein of gilts to enable blood sample collection without restraint. After collection of a control sample, gilts were restrained by use of a snare and samples were collected at 0.5, 3.5, and 6.5 minutes after start of restraint (0 minutes). At each time point, plasma β-endorphin and cortisol concentrations as well as WBC counts were recorded, and functional capacity of leukocytes in cultures of whole blood was assessed by means of mitogen-induced proliferation and interleukin-2 activity, virus-induced interferon-α concentration, and phagocytosis of zymosan particles.

Results

Concentrations of plasma β-endorphin and cortisol were increased at 3.5 and 6.5 minutes after start of restraint. At these times, virus-induced interferon-α concentration was decreased, whereas proliferative response to Concanavalin A and phytohemagglutinin increased in samples collected at 6.5 minutes.

Conclusion and Clinical Relevance

It was possible to snare pigs for the purpose of collecting blood samples and restrain them without causing excessive stress that would affect immunologic variables, provided that the collection procedure was completed within a few minutes. (Am J Vet Res 1998;59:421–425)

Free access
in American Journal of Veterinary Research

SUMMARY

Total protein concentration was determined in serum, bronchoalveolar lavage (bal) fluid, and nasal flush fluid obtained from specific-pathogen-free cats from birth to maturity and from adult conventionally raised cats. Protein components were analyzed by Immunoelectrophoresis and isoelectric focusing. Albumin, and α-, β-, and γ-globulins were among the proteins identified in bal fluid, and their isoelectric point ranged from 3.1 to 5.1. γ-Globulin was not detected in serum or bal fluid of newborn kittens before they had ingested colostrum. By day 3 after ingestion of colostrum, IgG was detected in high concentration in serum and was the predominant immunoglobulin in serum and bal fluid of older cats. Nasal flush fluid from cats > 6 months old contained albumin, and α-, β-, and γ-globulins, with IgA being the predominant immunoglobulin. Total protein concentration in nasal flush fluid increased progressively with increasing age, and albumin was the predominant protein. Protein concentration was significantly (P < 0.01) higher in bal fluid from conventionally raised adult cats than in that from specific-pathogen-free cats.

Free access
in American Journal of Veterinary Research

SUMMARY

To examine the influence of allergen-induced type-1 hypersensitivity on the pathogenesis of bovine respiratory syncytial virus (brsv) infection, we sensitized calves by aerosol to Micropolyspora faeni (mf) and challenge exposed them during infection with brsv. The development of mf-specific IgE serum concentrations was confirmed by elisa. The dynamics of arachidonic acid metabolism and histamine release during a type-1 hypersensitivity reaction in the bovine lung were studied by quantitating the concentrations of prostaglandin (pg)e2, pgf , pgi 2 as 6-keto-pgf , thromboxane (tx) A2 as txb 2, and histamine in plasma of brsv-infected and/or mf-sensitized/challenge-exposed calves. Four treatment groups were established: (1) brsv infection only, (2) aerosol sensitization to mf followed by brsv infection and aerosol challenge exposure to mf, (3) mf aerosol sensitization and challenge exposure without brsv infection, and (4) aerosol sensitization to mf followed by brsv infection without mf challenge exposure. Significantly increased concentrations of pgi 2 were associated with mf aerosol exposure, particularly when combined with brsv infection in group 2. After mf challenge exposure, txb 2 concentrations were significantly greater in the virus and mf challenge-exposed group 2. Individual calf data for the change in mf-specific IgE concentration between the first and second mf challenge exposures and the change in pg e2 concentration 30 minutes after the second mf challenge exposure had a highly significant direct correlation. Histamine concentrations were significantly greater in calves infected with brsv than in uninfected controls regardless of mf exposure. These data further substantiate the thesis that implicates type-1 hypersensitivity as a pathogenic mechanism in brsv-related disease.

Free 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

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

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