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F Blecha

Publications and source records attributed to F Blecha.

At least 73 records · Page 4Linked to original sources
PubMed1991

Measuring suitability of soybean products for early-weaned pigs with immunological criteria.

Two trials were conducted to determine the suitability of soybean products for baby pigs. Weanling pigs (n = 40 and 48 in Trials 1 and 2, respectively) were infused orally (6 g/d) with dried skim milk, soybean meal (SBM, 48% CP); soy protein concentrate, moist extruded soy protein concentrate, or soy protein isolate from d 7 to 12 of age. Pigs were then fed a diet containing the same protein source for 1 (Trial 1) or 2 (Trial 2) wk after weaning (d 21 of age). To avoid exposure of pigs to soybean proteins, the dams of pigs were fed a corn-corn gluten meal-based diet supplemented with lysine and tryptophan from d 109 of gestation. All pigs in Trial 1 were killed at 28 d of age, and samples of ileal digesta and small intestine were obtained. In Trial 2, the soy protein isolate was not included, and all pigs were fed a diet containing 4% soybean oil and 1.25% lysine for the last 3 wk of the trial. Growth performance, skin-fold thickness, after intradermal injection of extracts of the corresponding proteins, and anti-soy immunoglobulin G (IgG) titers were measured. Results indicated that pigs fed diets containing SBM had lower (P less than .05) villus height and xylose absorption but higher (P less than .05) serum anti-soy IgG titers and increased skin-fold thickness compared with the mean of pigs given milk and all other soy treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1991

Cytokines: applications in domestic food animals.

Cytokines such as human, bovine, and porcine interferons and human and bovine interleukin-1 and interleukin-2 have been used in vivo in cattle and pigs. Colony-stimulating factors and tumor necrosis factor alpha have been evaluated in vitro in food animals. Studies to evaluate cytokines in domestic food animals have shown that specific and nonspecific immunomodulation is possible in immunosuppressed or pathogen-exposed animals. Cytokine prophylaxis or therapy in food animals may have the greatest potential for control of respiratory disease and mastitis.

Animals↗
PubMed1991

In vitro and in vivo evaluation of effects of a heptanoyl tripeptide, FK-565, on porcine macrophage and lymphocyte function.

A series of experiments was performed in vitro and in vivo to determine the influence of FK-565, a heptanoyl tripeptide, on lymphocyte and macrophage function in swine. Compared with values for control cultures, mitogen-stimulated lymphocyte blastogenesis and interleukin-2 production were unaffected in cells preincubated with 0.1, 1.0, and 10.0 micrograms of FK-565/ml. Natural killer cell activity was increased by preincubation with 1.0 microgram of FK-565/ml; however, this increase was not statistically significant. In vitro treatment of porcine alveolar macrophages with FK-565 did not enhance cytolytic activity or bactericidal activity. In in vivo experiments, FK-565 given orally to pigs at concentrations of 6 or 60 micrograms.kg-1.d-1 for 5 days did not affect lymphocyte blastogenesis, interleukin-2 production, or alveolar macrophage bactericidal activity. A trend toward increased natural killer cell activity was evident in pigs treated with FK-565. In contrast, pigs treated with 6 micrograms.kg-1.d-1 had significantly (P less than 0.01) decreased alveolar macrophage cytolytic activity. These data indicate that at the dosages tested, FK-565 is not a suitable immunomodulator for enhancement of nonspecific immunity in swine.

Animals↗
PubMed1990

In vitro interactions of cytokines and bovine viral diarrhea virus in phytohemagglutinin-stimulated bovine mononuclear cells.

Bovine viral diarrhea (BVD) virus inhibited phytohemagglutinin (PHA)-stimulated bovine peripheral blood mononuclear cell (PBMC) proliferation and bovine interleukin-2 (IL-2) production. In the controls, the heat-inactivated BVD virus was not capable of suppressing the PHA-stimulated PBMC proliferation. Presence of exogenous cytokines, such as purified human IL-2, recombinant bovine interleukin-1 (rbovIL-1), recombinant bovine IL-2, and recombinant human IL-6 failed to reverse the BVD virus-induced immunosuppression. Also, we found that the BVD virus inhibited PHA and IL-2 induced proliferation of bovine PBMC in the early and late stages of activation. In summary, our data suggest that BVD virus induced immunosuppression was not due to destruction of the PBMC but may be inhibiting one or more of the important intracellular enzymes that may regulate PBMC proliferation.

Animals↗
PubMed1990

Inhibition of phytohemagglutinin-stimulated bovine mononuclear cell proliferation, interleukin-2 production and protein kinase C activity by a protein kinase C inhibitor, H-7.

1-(5-Isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), a potent and selective inhibitor of protein kinase C (PKC), inhibited PHA-stimulated bovine peripheral blood mononuclear cell (PBMC) proliferation, interleukin-2 (IL-2) production, and cytosolic PKC activity without affecting the cell viabilities. Presence of exogenous cytokines, such as purified human IL-2 or recombinant bovine IL-2 (rbovIL-2), reversed the H-7 inhibitory effects on PHA-stimulated PBMC proliferation. We conclude that the PKC enzyme plays an important role as a second messenger in bovine PBMC proliferation in the early stages of cell activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Rationale for using immunopotentiators in domestic food animals.

In the production of domestic food animals several situations exist where disease decreases production efficiency. Some of these diseases are exacerbated by a lowered or compromised immune response of the host. If immunomodulators can be used to augment immune function at critical periods during the production of food animals, such as the neonatal period, and prior to or during exposure to stressors or pathogenic organisms, then the economic loss caused by infectious disease should be reduced.

Adjuvants, Immunologic↗
PubMed1990

Antigenic variations in bovine viral diarrhea viruses detected by monoclonal antibodies.

Five murine monoclonal antibodies (MAbs) against the NADL strain of bovine viral diarrhea (BVD) virus were developed, identified, and characterized. Four of the MAbs were directed against a 53-kilodalton (kDa) viral protein, and one was specific to a 47-kDa polypeptide. Competitive radioimmunoassay showed that two MAbs were specific to related epitopes of the 53-kDa protein, and the other three MAbs were each specific to a different epitope. The MAbs were used to study heterogeneity among BVD virus strains. Various degrees of reactivity of cytopathic and noncytopathic virus isolates were detected by virus neutralization and immunofluorescence assays. The virus isolates were divided into six groups based on the neutralization test. The results indicated that the 53-kDa glycoprotein of BVD virus is the major protein involved in virus neutralization and that only a few epitopes of the protein contribute to the neutralization. None of the MAbs neutralized all the BVD virus isolates tested in this study, suggesting antigenic variations among BVD virus isolates.

Animals↗
PubMed1990

Effect of acute stressors on endocrinological and immunological functions in lambs.

Lambs were used to evaluate the effect of acute heat stress (HS) or restraint and isolation stress (RIS) on endocrinological and immunological functions. In Exp. 1, lambs were exposed to HS (35 degrees C) and control lambs (CN) were exposed to 21 degrees C for 24 h in two replicates (n = 8 lambs total per treatment). Samples of serum were obtained at frequent intervals for evaluation of cortisol; whole blood was obtained for total and differential leukocyte numbers and lymphocyte blastogenic function. The time-trends for cortisol between HS and CN lambs were different following treatment (P less than .005), but neither leukocyte numbers nor lymphocyte blastogenesis in response to mitogens were affected by acute exposure to the elevated ambient temperature. In Exp. 2, lambs (n = 6 per treatment) were given a 6-h RIS treatment and control lambs remained in their home stanchions (CON). Plasma and serum were obtained frequently during treatment and continued until 24 h after the onset of treatment. Plasma was evaluated for adrenocorticotropic hormone (ACTH) and serum was assayed for cortisol. Samples of whole blood also were obtained before and at 6, 12 and 24 h after the onset of treatment for determination of total and differential leukocyte numbers and lymphocyte blastogenic responses to mitogens. Both ACTH and cortisol were elevated in response to RIS; the profiles of these hormones over the 24-h bleeding period differed for RIS and CON lambs (P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1990

Transient hypersensitivity to soybean meal in the early-weaned pig.

An experiment was conducted to determine whether baby pigs develop hypersensitivity to dietary soybean proteins. Thirty-two pigs were orally infused with either dried skim milk (5 g/d; control) or soybean meal (48% CP; 5 g/d) from d 7 to 14 after birth. Sows were fed a corn-corn gluten meal-based diet supplemented with lysine and tryptophan to avoid exposure of pigs to soybean proteins. Pigs were weaned at 21 d of age and fed diets containing either soybean meal or milk proteins until d 56. One half of the pigs were killed at 28 d of age and the rest at 56 d of age. Segments of small intestine were collected, and intraepithelial lymphocytes were isolated. At 28 d of age, pigs fed diets containing soybean meal had lower (P less than .05) villus height (221 vs 298 microns) and rate of gain (86 vs 204 g/d) than control pigs did. Pigs fed a diet containing soybean meal had higher (P less than .05) immunoglobulin G (IgG) titers to soybean protein than did pigs fed a milk protein-based diet. Blood and intestinal lymphocytes collected on d 28 and 56 did not exhibit any proliferative response when cultured with purified soy proteins (2.5 or 5 microns/ml). Phytohemagglutinin- and pokeweed mitogen-induced lymphocyte proliferations were higher (P less than .05) at d 56 than at d 28, but there were no differences attributable to protein source. There were no differences (P greater than .05) in skin-fold thickness measurements following intradermal injection with soy or milk proteins. Decreased villus height and increased serum IgG titers to soybean proteins coinciding with inferior performance of early weaned pigs fed diets containing soybean meal indicate that conventionally processed, commercial soybean meal may retain some antigens that can cause transient hypersensitivity in piglets.

Animals↗
PubMed1990

Pituitary-adrenocortical and lymphocyte responses to bromocriptine-induced hypoprolactinemia, adrenocorticotropic hormone, and restraint in swine.

A study was conducted with castrated male pigs (barrows) to evaluate effects of bromocriptine-induced hypoprolactinemia (6 days) on basal and adrenocorticotropic hormone (ACTH)-altered (single injection) pituitary-adrenocortical function, on lymphocyte proliferative responses, and on interleukin 2 production. In addition, the study was designed to measure the short time course of pituitary-adrenocortical and lymphocyte responses to ACTH and to a 30-min restraint stressor. Blood samples were taken via indwelling jugular catheters at -0.5, +0.5, +2, and +5 hr (with reference to time of acute treatment exposure) on Day 6 of the study. Lymphocyte responses were measured only at the 2-hr interval. Exposure (6 days) to bromocriptine (CB154) was associated with 53% reductions (P less than 0.05) in plasma prolactin (1.37 +/- 0.13 vs 0.60 +/- 0.04 vs 0.68 +/- 0.08 ng/ml) when averaged across all time intervals in control, CB154-treated, and CB154 + ACTH-treated pigs, respectively. The reductions in plasma prolactin were associated with a reduction (P less than 0.05) in basal plasma cortisol at only one time interval (+0.5 hr) when CB154-treated pigs were compared with controls (17.7 +/- 4.2 vs 26.9 +/- 3.2 ng/ml). CB154 had no effect on plasma ACTH or growth hormone concentrations for the time periods at which they were measured. CB154 treatment produced numerical, but not statistically significant, 38% reductions in interleukin 2 production (6.31 +/- 1.8 vs 3.91 +/- 1.47 units/ml). Lymphocyte proliferative responses to the mitogen concanavalin A and interleukin 2 production decreased 65 and 75% (P less than 0.05), respectively, 2 hr subsequent to ACTH administration when compared with control animals. Hence, under the conditions of this study, only a modest association between lowered plasma prolactin concentrations and basal cortisol concentrations was evident. The data suggest the absence of dopamine regulation of basal plasma ACTH in pigs and provide evidence for a rapidly occurring inhibitory effect of ACTH administration on specific lymphocyte activities.

Adrenocorticotropic Hormone↗
PubMed1990

Adjuvanticity of recombinant bovine interleukin-1 beta: influence on immunity, infection, and latency in a bovine herpesvirus-1 infection.

Recombinant bovine interleukin-1 beta (rBoIL-1 beta) was administered to calves in conjunction with a bovine herpesvirus-1 (BHV-1) vaccine. All calves were immunized against BHV-1 and three groups received rBoIL-1 beta at 33, 100, or 330 ng/kg on days 1 and 15; control animals received physiological saline. All calves were challenged with BHV-1 on day 22. Total leukocytes were increased by rBoIL-1 beta, primarily by causing neutrophilia and monocytosis; CD4/CD8 ratios tended to be increased in rBoIL-1 beta-treated animals. Serum neutralizing antibody titers and cytotoxic responses against BHV-1-infected bovine kidney fibroblasts were increased and virus excretion was decreased in rBoIL-1 beta-treated calves. On days 58 and 59, control and 100 ng/kg rBoIL-1 beta-treated calves were injected with dexamethasone (.04 mg/kg). Virus excretion was less and clinical signs of BHV-1 infection were lower in rBoIL-1 beta-treated calves after dexamethasone injection. These data suggest that rBoIL-1 beta may be an effective adjuvant to BHV-1 immunization.

Adjuvants, Immunologic↗
PubMed1990

Human recombinant interleukin-2 augments porcine natural killer cell cytotoxicity in vivo.

Immunological parameters of porcine peripheral blood mononuclear cells after in vivo injections of human recombinant interleukin-2(125) (HrIL-2) were studied. Eighteen pigs (6 pigs/group) were injected with either 10(4) or 10(5) units/kg body weight of human rIL-2 or an equivalent volume of sterile physiological saline (control) on days 0 through 4. All pigs were immunized with an E coli J5 bacterin on day 0. Cytolytic activity to porcine fibroblasts (PK-15) was increased (P less than 0.02) in pigs treated with HrIL-2 when compared to control animals. Cytotoxicity to K-562 cells also showed a tendency (P less than 0.08) towards increased cytolytic activity in the HrIL-2-treated pigs. Lymphocyte blastogenesis, IL-2 production, and serum iron concentrations did not differ between treatment groups. Antibody concentrations to E coli J5 antigens increased significantly (P less than 0.05) in all groups after immunization, but there were no differences between treatment groups. These data suggest that in vivo injections of Hr-IL-2 increase natural cytotoxic cell activity in pigs without influencing other immune activities.

Animals↗
PubMed1990

Bovine recombinant granulocyte-macrophage colony-stimulating factor enhancement of bovine neutrophil functions in vitro.

Neutrophils were purified from blood of dexamethasone-treated (0.04 mg/kg of body weight) and untreated calves. Cells were untreated (controls) or cultured in media containing 5 or 10 ng of bovine recombinant granulocyte-macrophage colony-stimulating factor (rbGM-CSF)/ml for 10 to 12 hours before being tested for various functions. Dexamethasone treatment of calves decreased luminol-dependent chemiluminescence, decreased phagocytosis of Pasteurella multocida and several Staphylococcus spp by various degrees, and decreased antibody-dependent cell-mediated cytotoxicity against bovine herpesvirus-infected cells by 26 to 32%. The percentage phagocytosis of coagulase-positive S aureus and S intermedius was higher than that of coagulase-negative S epidermidis for neutrophils from all calves. Culture of neutrophils with rbGM-CSF significantly increased (P less than 0.05) all of the aforementioned functions, compared with control neutrophils; however, rbGM-CSF-induced increases in function tended to be higher in neutrophils from dexamethasone-treated calves than in neutrophils from untreated calves.

Animals↗
PubMed1989

Bovine recombinant interleukin-2 augments immunity and resistance to bovine herpesvirus infection.

The in vivo administration of bovine recombinant interleukin-2 (rIL-2) was evaluated in calves vaccinated and then challenged with bovine herpesvirus-1 (BHV-1). In Experiment 1, 24 calves were allotted to four groups: control; bovine rIL-2; BHV-1 vaccine (modified-live); and bovine rIL-2 + BHV-1 vaccine. Serum neutralizing antibody titers to BHV-1 were increased sixfold, and virus shedding was fourfold less in calves vaccinated and treated with rIL-2 (25 micrograms/kg, intramuscularly) when compared to calves that received vaccine only. Treatment with rIL-2 induced lymphokine-activated killer activity that was eliminated by pretreating effector cells with complement and a monoclonal antibody (B26A) specific for the sheep red blood cell receptor. The rIL-2 treatment in BHV-1-vaccinated calves increased the calves' ability to withstand a BHV-1 challenge. However, during treatment with rIL-2, calves developed diarrhea and mild fever that abated after IL-2 treatment was stopped. A second experiment was then conducted to determine a dose of rIL-2 that would enhance immunity to BHV-1 without causing adverse side effects. Twenty-five calves were allotted to five groups that received injections of rIL-2 at 0.0, 25.0, 2.5, 0.25, or 0.025 micrograms kg-1 day-1 for 5 days. All calves received a modified-live BHV-1 vaccine. Calves treated with 25.0 micrograms kg-1 day-1 showed similar adverse side effects as in the first experiment but all other calves were normal. Compared to control calves, those treated with 25.0, 2.5, and 0.25 micrograms kg-1 day-1 of rIL-2 had higher (P less than 0.05) serum antibody titers to BHV-1 and following challenge lower (P less than 0.05) BHV-1 titers in nasal secretions; additionally, clinical disease as evidenced by nasal and ocular discharge was less severe (P less than 0.05). In vitro cytotoxic responses against BHV-1-infected bovine kidney cells were increased (P less than 0.05) in calves treated with rIL-2 in a dose dependent manner. These data suggest that bovine rIL-2 at 2.5 to 0.25 micrograms/kg may be an effective adjuvant to immunization.

Adjuvants, Immunologic↗
PubMed1989

Activated porcine alveolar macrophages: are biological response modifiers the answer?

We report that 75% of conventionally housed 3- to 4-week-old swine already have detectable activated alveolar macrophages as measured by cytotoxicity of tumor cells. These macrophages can not be further activated by the biological response modifier N-acetylmuramyl-L-alanyl-Disoglutamine-2H2O (MDP). These macrophages lose cytotoxic activity when cultured for 24 h and this loss of activity can not be reversed by MDP. We suggest that MDP biological response modifier therapy of swine alveolar macrophages may not be a useful technique in preventing respiratory disease in swine.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Effects of bovine respiratory disease viruses and isoprinosine on bovine leukocyte function in vitro.

Peripheral blood mononuclear cells obtained from 4- to 6-month-old-calves were inoculated in vitro with bovine herpesvirus-1, parainfluenza-3, or bovine virus diarrhea viruses. No increase in infectious virus progeny was observed; however, the viruses were detected in the cells for at least 96 h post-infection without any significant reduction in cell viability. The three viruses, either alone or in combination, suppressed phytohemagglutinin-induced proliferation of the mononuclear cells. The greatest suppression was observed in cultures inoculated with bovine virus diarrhea virus. Addition of isoprinosine partially restored this viral-induced suppression of proliferative response, and the efficiency of reversal was greater in bovine virus diarrhea virus-infected cells. Interleukin-2 activity was higher in cultures of virus-infected mononuclear cells than in cultures of non-infected cells.

Animals↗
PubMed1989

Evaluation of a biological response modifier: effects on starter pig performance.

The influence of a biological response modifier (FK-565) on weanling pig performance was evaluated. One hundred twenty-five weanling pigs (weaned at 21 +/- 3 d) averaging 6.3 kg were utilized in a 35-d growth trial. Dietary treatments included a basal diet (1.25% lysine, corn-soybean meal-dried whey), the basal plus .1, 1 or 10 ppm FK-565 and the control plus an antibacterial combination containing chlortetracycline, sulfamethazine and penicillin. Performance was recorded weekly, and on d 35 all pigs were bled for whole blood and serum chemistry profiles and then were euthanatized. Heart, liver, kidneys and spleen weights were recorded. Also, gross and histological examinations were made of these organs, as well as sections of lung, ileum, bone marrow, thymus and mesenteric lymph node. By d 14, pigs fed the antibacterial diet gained faster (P less than .06) than pigs fed the control and FK-565 diets. However, no differences (P less than .10) in feed intake at d 14 or efficiency of feed utilization at either d 14 or 35 were observed. For the overall 35-d trial, ADG was greater (P less than .01) for pigs consuming the antibacterial diet than for pigs consuming control and the FK-565 diets. Pigs consumed more of the antibacterial diet than of the other diets (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗