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Summary

Direct effects of equine infectious anemia virus (eiav) on hematopoiesis in vitro were studied. Bone marrow mononuclear cells from clinically normal horses were incubated with 100 TCID50 of ELAV/107 cells. These cells were cultured to assay for colonies derived from erythroid pro-genitors, granulocyte/monocyte progenitors, and fibroblastic progenitors. The eiav had a selective suppressive effect on the erythroid progenitors. Colony-forming units-erythroid were suppressed to 80% of that for medium controls (P = 0.011). Burst-forming units-erythroid were suppressed to 70% of that for medium controls (P = 0.003). Significant effect was not apparent on colony-forming units-granulocyte/macrophage or on colony-forming units-fibroblastic.

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in American Journal of Veterinary Research

Summary

Ninety steers with an average weight of 214 kg were purchased at 2 feeder calf sales and transported 70 to 100 km. On arrival at the feedlot, steers were weighed and identified, blood was withdrawn, and the steers were vaccinated against bovine herpesvirus-1 (bhv-1) and parainfluenza3 (pi3), using a modified live vaccine, and randomly assigned to treatment groups. Treatments were: control (no supplemental zinc); zinc methionine; and zinc oxide. The control diet contained 26 mg of zinc/kg diet, and zinc was added in treatments 2 and 3 to provide 25 mg of supplemental zinc/kg diet. Neutralizing antibody titers were determined on serum samples taken on days 0 and 14 as a measure of the immune response to bhv-1 and pi3 vaccination. Weight gains for the 28-day study were similar across treatments. Dry matter intake tended to be higher in steers fed supplemental zinc from either source, because steers fed zinc methionine and zinc oxide consumed 5.2 and 4.4% more feed, respectively, than controls. Antibody titers against bhv-1 tended to be higher in steers supplemented with zinc methionine on day 14. Differences between treatments were not found for pi3 titers. Mortalities did not occur and morbidity rate was low.

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in Journal of the American Veterinary Medical Association

SUMMARY

The purpose of this in vitro study was to determine whether Pasteurella haemolytica capsular extract (ce) damages bovine pulmonary endothelial cells (ec) directly or through neutrophil-mediated mechanisms. Chromium 51-labeled ec were treated with the following variables: ce (1, 10, and 100 ng of protein/ml), ce and bovine neutrophils (106 cells/well), and ce and polymyxin B (500 U/ml). Although only minimal damage to ec occurred by 5 hours after treatment, by 22 hours after treatment, the 10-ng and 100-ng ce dose produced severe damage to ec, as indicated by 51Cr release, cellular detachment, and loss of monolayer confluency. The component in the ce that was toxic to the ec was lipopolysaccharide, evidenced by effective neutralization of the toxic effect with polymyxin B. Neutrophils inhibited the ce-mediated ec toxicity and were activated, as indicated by shape change and adhesion to ec monolayers. We concluded that the lipopolysaccharide component of ce causes direct damage to ec, which can be attenuated by neutrophils and polymyxin B.

Free access
in American Journal of Veterinary Research

Summary

Newborn pups from 4 large litters were allotted to 6 groups to determine effect of time and route of administration on absorption of an alternate source of immunoglobulin. Selective absorption of specific classes of immunoglobulins was also investigated. The alternate source of immunoglobulin consisted of pooled serum that was administered either po or sc. Control groups were either left with the dam (group C1) or fed milk replacer (group C2). Blood samples were collected from pups at birth and 24 hours. Immunoglobulin (IgA, IgG, IgM) concentrations were determined by use of radial immunodiffusion on samples of pooled serum, colostrum, and pups’ serum (birth and 24 hours).

Serum IgA concentration was less than the sensitivity of the procedure and was not included in the statistical analysis. Pups fed 8 ml of pooled serum at birth and 12 hours later (group T1) absorbed more (P< 0.05) IgG and IgM than did group-C2 pups, but less (P < 0.05) than did group-C1 pups. Pups fed 8 ml of pooled serum at 12 hours only had significant (P < 0.05) increase of IgG concentration, but no absorption of IgM (P > 0.05) at 24 hours, compared with control pups (group C2). Pups administered 8 ml of pooled serum SC at birth (group SC1) had similar (P > 0.05) absorption of IgG and higher (P < 0.05) absorption of IgM than did pups of group T1. Pups administered 16 ml of pooled serum sc at birth had the highest increase of IgG and IgM concentrations of all treatment groups, but immunoglobulin concentrations were lower (P < 0.05) than those for group-C1 pups. Absorption of IgG was favored, compared with IgM, when pooled serum was fed.

Results indicate clearly that intestinal absorption of immunoglobulins is minimal after 12 hours and thus, another route of administration should be used. Pups in groups SC1 and T1 had similar absorption of IgG, despite lower IgM absorption in pups of group T1. This lower IgM concentration in group-T1 pups may have been the result of selective intestinal absorption or the consequence of low number of pups per group. Subcutaneous administration of 16 ml of pooled serum was the most successful alternative to colostrum, with minimal pain to pups if serum was administered slowly. Serum IgG concentration in Cl pups was higher than expected and probably was attributable to the amount of colostrum available to the pups.

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in American Journal of Veterinary Research

Summary

A retrospective study of stored feline serum samples was done to determine the infection rate of feline immunodeficiency virus in cats in central Missouri. Infected cats were compared with uninfected cats subjected to the same selection criteria on the basis of signalment, clinical signs, and cbc abnormalities. A significant incidence of virus infection was found in male cats. Neither age nor breed predilection could be identified. Infected cats were more likely to be anemic and leukopenic because of neutropenia. Cellulitis and neoplasia were more common in infected cats. A spectrum of disease severity was seen in infected cats ranging from no clinical signs to signs of severe chronic inflammatory disease. Infected cats were more likely to have clinical disease. Mean survival of infected cats was 24.4 months from the time of diagnosis.

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in Journal of the American Veterinary Medical Association

Summary

Cache Valley virus (cvv), an arbovirus indigenous to the United States, has been implicated as an important teratogenic agent in sheep. The prevalence and distribution of Texas sheep with cvv-specific antibody were investigated. In 1981, 19.1% of 366 sheep located in 22 counties of Texas had antibodies specific for cvv. Of 50 flocks examined in the major sheep-producing counties in Texas, 34 had sheep with antibodies that reacted with cvv, including all sheep tested in 6 flocks that were seropositive. Sera obtained from sheep at the Texas Agricultural Experiment Station at San Angelo between 1986 and 1989 were also examined for cvv-specific antibody because this flock was the subject of the episode of cvv-associated congenital malformations during the 1986 and 1987 lambing season. Approximately 8.6% of 104 sheep in 1986, 63.4% of 164 in 1987, 11.3% of 44 in 1988, and 71.9% of 89 in 1989 from the Texas Agricultural Experiment Station at San Angelo tested were seropositive. The data indicate that cvv infections in sheep were widespread in Texas in 1981 and that the virus is enzootic in sheep at the Texas Agricultural Experiment Station in San Angelo, where the episode of congenital malformations had initially been reported in 1987.

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in Journal of the American Veterinary Medical Association

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
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

SUMMARY

Sublethal irradiation of BALB/c mice 4 hours prior to inoculation with 5 × 104 virulent Brucella abortus, caused significant (P < 0.01) reductions in bacterial numbers in comparison with numbers in unirradiated controls. Numbers of brucellae in the spleen were significantly lower by 5 days after inoculation and decreased thereafter, so that at 2 and 3 weeks after inoculation, there were up to 1,000-fold fewer organisms in the spleen of irradiated mice. The number of brucellae in the spleen increased in irradiated mice thereafter. The course of events in the liver was similar, but developed more slowly, and peak differences in bacterial numbers were about 1 log less. These phenomena were not attributable to differences in implantation of brucellae in the liver or spleen, nor to an abnormal distribution of organisms in other organs of irradiated mice. Irradiation of mice during the plateau phase of infection also resulted in significant (P < 0.05) reductions in bacterial counts in the spleen during the succeeding 4 weeks. Macrophage activation in the spleen, measured by a Listeria monocytogenes-killing assay, was significantly (P < 0.01) increased by irradiation alone at 1 week after inoculation and at that time was significantly (P < 0.01) greater in B abortus -infected, irradiated mice than in B abortus-infected controls. Histologic, cytologic, and immunologic studies revealed that the decrease in numbers of organisms between 1 and 2 weeks after inoculation in irradiated mice occurred at a time when their immune response to B abortus was suppressed and when numbers of neutrophils and monocytes infiltrating the spleen were significantly (P < 0.01) diminished. The increase in numbers of B abortus in organs of irradiated mice that began after the third week coincided with recovery of the immune response and an increase in numbers of neutrophils and monocytes in the infected organs. The course of B abortus infection was not substantially altered during the first 11 days after inoculation in mice infected at the height of a profound monocytopenia and neutropenia induced by azathioprine, a drug that by itself failed to activate macrophages. We hypothesized that, in irradiated mice, a rapid radiation-induced activation of resident macrophages to a brucellacidal state was coupled with an absence of newly formed monocytes in which virulent strains of B abortus could establish persistent infection, and that as susceptible monocytes emerged in mice recovering from the effects of irradiation, chronic infection became established.

Free access
in American Journal of Veterinary Research