Biomedical subjects

C Fossum

Publications and source records attributed to C Fossum.

At least 37 records · Page 2Linked to original sources

PubMed1998

Humoral immune responses to Mycoplasma hyopneumoniae in sows and offspring following an outbreak of mycoplasmosis.

Previously healthy sows, seropositive to Mycoplasma hyopneumoniae, developed clinical signs of mycoplasmosis, as well as increasing amounts of antibodies to M. hyopneumoniae during an outbreak of the disease in a herd. During the early phase of the outbreak, young piglets (2 weeks) with maternal antibodies remained healthy while older seronegative piglets (4-7 weeks) developed the disease. The duration of the maternal antibodies to M. hyopneumoniae varied between litters and was related to the amount of antibodies in the serum of the dam. In sows, the level of serum antibodies decreased continuously from 4 weeks ante partum to partus, and the level of antibodies in the whey of colostrum was comparable to that in serum 4 weeks ante partum. After loss of maternal antibodies to M. hyopneumoniae, seropositive animals were not found among piglets younger than 9 weeks. Therefore peripheral blood mononuclear cells (PBMC) were collected from various age categories of piglets in order to measure the ability to produce antibodies to M. hyopneumoniae in vitro. PBMC obtained from piglets aged 1 and 3 weeks produced few antibodies to M. hyopneumoniae. Significantly higher levels of antibodies to M. hyopneumoniae were produced by PBMC obtained from pigs aged 5-9 weeks. Thus, the ability of PBMC to produce antibodies to M. hyopneumoniae in vitro seemed to be age-dependent.

Animals↗

PubMed1998

Actinobacillus pleuropneumonia serotype 2--effects on the interferon-alpha production of porcine leukocytes in vivo and in vitro.

Effects of a bacterial infection on the IFN-alpha production in vivo and in vitro were studied in eight specific pathogen free pigs experimentally infected with Actinobacillus pleuropneumoniae. Clinically, the experimental infection was manifested as a febrile stage which lasted approximately one week and by signs of respiratory disease. The Aujeszky's disease virus (ADV) induced IFN-alpha production, assessed in whole blood cultures, was increased for the infected pigs during the febrile stage. Potentiating effects on the IFN-alpha production could be transferred to cultures of purified peripheral blood mononuclear cells with sera collected from the infected pigs during this period of time. Although the experimental infection with A. pleuropneumoniae did not induce any detectable amounts of IFN-alpha in serum or nasal secretion, both a phenol-extract and a heat-inactivated preparation of the bacteria induced low levels of IFN-alpha in cultures of purified PBMC. The interferogenic structures of the bacteria were not identified but there were indications that the bacteria induced IFN-alpha production in the same cell type as ADV.

Actinobacillus Infections↗

PubMed1998

Cytokines as markers for infections and their effect on growth performance and well-being in the pig.

Exposure to micro-organisms commonly elicit the production of cytokines. These soluble factors enhance several innate immune functions that aim to limit the spread of infection. Further, many of the pro-inflammatory cytokines regulate the ensuing specific immune response. In addition to their effects on cells of the immune system, cytokines also are important regulators in the so called immune-neuroendocrine network. The microbial structures that are necessary for induction of cytokine production are not conclusively determined but in general, bacteria preferentially induce the production of IL-1, TNF-alpha, IL-6, and IL-8, whereas virus induce the production of Type 1 interferons (IFN-alpha/beta). The onset of production of these cytokines is rapid, and several of them may reach systemic levels during a short period after infection. Thus, cytokines can serve as markers for ongoing infections and be used for discrimination between infections of bacterial or viral origin. Results from experimental and field studies show that serum IFN-alpha and IL-6 seem to be useful markers for ongoing (subclinical) viral and bacterial infections, respectively, in the pig. Consequently, demonstration of these cytokines can be valuable tools in heard health monitoring programs.

Actinobacillus Infections↗

PubMed1998

Signs of infections and reduced immune functions at weaning of conventionally reared and specific pathogen free pigs.

The growth rate and several immune parameters were recorded to monitor the performance, health and immune status of 40 piglets in a conventional farrow to finish herd. In addition, effects of weaning on immune parameters were studied under minimal influence of infections in 20 specific pathogen free (SPF) pigs. The growth rate of the conventionally reared pigs decreased after weaning and after allocation of pigs to new premises. Around weaning a considerable number of pigs displayed interferon-alpha (IFN-alpha) in serum, indicating the spread of viral infections. Bacterial infections were indicated by elevated numbers of circulating neutrophilic granulocytes during the weaning period. Functional in vitro tests of peripheral blood mononuclear cells (PBMC) revealed that the Concanavalin A (Con A) induced proliferation decreased both after weaning and after transfer of the conventionally reared pigs to the finishing unit. The decreased proliferation observed after weaning was accompanied by decreased interleukin-2 (IL-2) production in response to the mitogen. A reduced IL-2 producing capacity after weaning was confirmed with PBMC obtained from the SPF pigs. Flow cytometric analyses of these cells showed that the proportion of PBMC expressing IL-2 receptors (IL-2R+) was decreased 3 and 6 days after weaning when cultured in the absence of mitogen while the proportion of IL-2R+ cells was unaltered in Con A stimulated cultures. Thus indications of reduced immune function coincided in time with signs of infections, especially around weaning.

Animals↗

PubMed1998

Effects of stress resulting from short-term restraint on in vitro functional capacity of leukocytes obtained from pigs.

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 beta-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-alpha concentration, and phagocytosis of zymosan particles. RESULTS: Concentrations of plasma beta-endorphin and cortisol were increased at 3.5 and 6.5 minutes after start of restraint. At these times, virus-induced interferon-alpha 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.

Animals↗

PubMed1998

Temporary suppression of cell-mediated immunity in standardbred horses with decreased athletic capacity.

Eighty Standardbred horses, originating from 5 training campuses, with decreased athletic performance in association with symptoms such as intermittent fever and mild pharyngitis were examined. As control animals, 10 horses from a stable with normally performing horses were used. Virus isolation and clinico-chemical and serological tests were performed. Lymphocyte proliferation tests were carried out to evaluate the capacity of the cell-mediated immunity. In addition, a bioassay for equine type I interferon, as a marker for early viral infections, was established. No specific microbe could be linked to these symptoms, but there was a temporary suppression of the cell-mediated immunity, which might be explained by the serological evidence of an EHV-2 and/or rhinovirus infection.

Animals↗

PubMed1997

Toxoplasma gondii infection in the mountain hare (Lepus timidus) and domestic rabbit (Oryctolagus cuniculus). II. Early immune reactions.

As already reported, the mountain hare is much more susceptible than the domestic rabbit to oral inoculation with Toxoplasma gondii, as judged by pathological changes and dissemination of parasites within the body. In the present paper, further interspecies variations are reported. Concentrations of the acute phase reactant haptoglobin were raised in hares but not in rabbits one week post-infection (pi), probably reflecting the severe tissue damage present. No difference in the early humoral immune response of hares and rabbits was found, both species producing IgM and IgG antibodies to T. gondii one week pi. Lymphocyte stimulation tests performed before and one week after inoculation showed a high proliferative response to the parasite in blood cell cultures from rabbits but not hares. The fatal outcome of T. gondii infection in the hares is probably due, at least in part, to the lack of cellular response.

Animals↗

PubMed1997

Bovine leukemia virus: early reflections in blood after an experimental infection of calves.

In order to study early alterations in the blood following infection with bovine leukemia virus (BLV) in the natural host, 15 calves were inoculated with blood from a BLV-positive donor cow. The humoral immunological response was followed by ELISA for 2 months. Seroconversion to BLV was demonstrated at 4-5 weeks post-infection. Total and differential leukocyte counts were performed. Acute lymphocytosis was observed at the time of seroconversion in the majority of the experimental calves. By the aid of monoclonal antibodies (mAbs), the proportion as well as the total number of lymphoid cells were studied in four of the calves, applying analytical flow cytometry. At the time of seroconversion the percentage of B-cells increased from 19.1 +/- 7.5% to 37.9 +/- 15.8%, and the T-cells (CD2+) decreased from 36.7 +/- 7.3% to 22.7 +/- 6.0%, the latter being attributable to decreases in the percentage of CD4+ as well as CD8+ T-cells for the infected calves together. Subsequently, altered B/T ratios were observed. In one of the calves an increase in the absolute number of CD5+ cells coincided with an increase in total B-cells. The early phenotypic alterations in lymphocyte subsets, before and after seroconversion to BLV, were comparable to those of non-lymphocytotic and persistent lymphocytotic cattle, respectively. Sera from 15 calves were tested for the presence of interferon (IFN), as measured by antiviral activity. BLV does not appear to induce the production of IFN.

Animals↗

PubMed1997

Tissue chambers--a useful model for in vivo studies of cytokine production in the pig.

An in vivo tissue chamber model was developed to enable studies of local cytokine production and cellular events during inflammatory and immune reactions in the pig. Tissue chambers made of sialistic rubber tubing were surgically implanted in the subcutaneous tissue- and samples of tissue chamber fluid (TCF) and inflammatory cells were collected by aspiration with a syringe. To evaluate the model for local cytokine production, two cytokine inducers, polyribinosinic-polyribocytidylic acid (poly I:C) and fixed Aujeszky's disease virus infected PK15 cells (ADV-PK15), were injected into the tissue chambers and samples of TCF were collected 0, 4, 8, 12, 24 and 48 h post injection. Poly I:C injections induced local production of interferon-alpha (IFN-alpha) as well as tumor necrosis factor (TNF) in the TCF but kinetic differences in the production of the cytokines were noted. Poly I:C also induced an increase in cell numbers in the TCF, mainly due to increased neutrophil numbers. Injections of ADV-PK15 induced local IFN-alpha production in the TCF as long as the pigs were serologically negative to ADV. Immunofluorescence and in situ hybridization techniques could be applied for characterization of TCF cells. Moreover, cells recovered from the tissue chambers were viable and could be used in functional in vitro tests. Taken together, this tissue chamber model could prove very useful in in vivo studies of inflammatory/immune responses and cytokine production in the pig.

Animals↗

PubMed1995

Lectins inhibit the Aujeszky's disease virus-induced interferon-alpha production of porcine peripheral blood mononuclear cells.

The interaction between virus and peripheral blood mononuclear cells (PBMC) required to elicit the production of interferon-alpha (IFN-alpha) by the so-called natural interferon-producing cell is unknown. However, results from inhibition experiments suggest that viral glycoproteins are essential in this IFN induction process. We demonstrate here that cellular glycoproteins also appear to be involved in the initiation of IFN-alpha production. Lectins, that is, sugar binding glycoproteins, inhibited the Aujeszky's disease virus-induced IFN-alpha production of porcine PBMC by up to 99%. The level of inhibition varied with lectin used (concanavalin A, Galanthus nivalis lectin, Helix pomatia lectin, and lentil lectin). Preincubation experiments with porcine cells and concanavalin A (ConA) revealed that the lectin exerted its major effect directly on the PBMC. Although the IFN-alpha production in some cases was reduced by more than 90%, the PBMC were still able to proliferate in response to mitogenic lectins. The ConA-mediated inhibition of the IFN-alpha production was reduced if the lectin was added later than 6-8 h after the start of induction and was not mediated by soluble factors. Both orthovanadate and staurosporine inhibited the IFN-alpha production and did not relieve the ConA-mediated inhibition. Thus, ConA seems to interfere with the early events during IFN-alpha induction, but the mechanisms behind this interference could not be clarified.

Alkaloids↗

PubMed1994

Genetic variation in parameters reflecting immune competence of swine.

Genetic variation in total and differential white blood cell (WBC) counts, phagocytic capacity of polymorphonuclear leukocytes (PMNL), virus induced interferon-alpha (IFN-alpha) production, mitogen induced proliferation and interleukin 2 (IL-2) production of mononuclear cells (MNC) in vitro was studied in blood collected from 124 Yorkshire piglets, aged 8 weeks. The piglets were the offspring from 12 sires and 31 dams. Data from an earlier experiment, including 96 piglets of seven sires and 24 dams, were added when estimating heritabilities for Con A induced proliferation and IL-2 production. The highest heritability (h2 = 0.87 +/- 0.41) was estimated for the total number of PMNL. Medium high heritabilities (h2 = 0.3-0.4) were estimated for the phagocytic capacity of PMNL, Con A induced proliferation and IL-2 production and the total number of WBC, while the heritability estimates were lower (h2 = 0.00-0.08 +/- 0.12) for the total number of lymphocytes, serum concentrations of Ig and IFN-alpha production. Pronounced differences between litters from various dams were found for total number of lymphocytes, IFN-alpha production, Con A induced proliferation and IL-2 production. The Con A induced proliferation was positively correlated (r = 0.48, P < 0.001) with the IL-2 production and both these parameters were correlated (r = 0.44 and 0.37, respectively, P < 0.001) to the virus induced IFN-alpha production. Despite these positive correlations, no parental offspring group was uniformly superior across all traits measured. However, the heritabilities estimated for the immune parameters are sufficiently high to be used as genetic markers in selection for general immune competence of swine.

Animals↗

PubMed1994

Influence of experimentally induced endogenous production of cortisol on the immune capacity in swine.

Field studies have suggested that 'stressors', such as transportation and mixing, might interfere with the immune competence of pigs. Therefore, an experimental model was established to study the influence of elevated concentrations of circulating cortisol on the immune capacity in swine. Three experimental groups, with six pigs in each, were immunized twice, 4 weeks apart, with Mycoplasma hyopneumoniae antigen. Endogenous production of cortisol was induced by intramuscular injection of adrenocorticotropic hormone (ACTH) twice daily. One group received ACTH during the week before and after the second immunization, one group during the week after the second immunization only, while one group served as untreated controls. The treatment with ACTH induced high, but physiological, concentrations of cortisol in plasma. Simultaneously, the number of lymphocytes per milliliter blood decreased while the neutrophil number increased. The elevated concentrations of cortisol also coincided with reduced proliferation and interleukin-2 production by blood lymphocytes stimulated with the mitogens concanavalin A and phytohemagglutinin in vitro, while the responses to pokeweed mitogen were less affected. The suppression of mitogen responses was more pronounced in cultures of whole blood than in cultures of purified peripheral blood mononuclear cells (PBMC). Antibody production, induced by M. hyopneumoniae in cultures of purified PBMC was also inhibited by ACTH treatment. Both the rate of increase and the magnitude of the antibody production induced by the primary immunization were reduced. In contrast, no effects of ACTH treatment were recorded for the response to the second immunization or on the serum levels of antibodies to M. hyopneumoniae.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1994

Genetic and stress-mediated influence on Aujeszky's disease virus induced interferon-alpha production in porcine leukocytes.

The ability to produce interferon-alpha (IFN-alpha) in vitro was measured in blood from 200 F2-crosses between European wild boar and Swedish Yorkshire pigs, originating from a reference pedigree for gene mapping. A total of 200 pigs of 44 litters, descendent from 4 boars and 22 sows, were stressed by transportation together with non-littermates for 5 h. Blood samples were collected from each individual twice, i.e. immediately before transportation and the day after transportation. IFN-alpha production was induced in whole blood cultures by a monolayer of fixed, Aujeszky's disease virus infected, porcine kidney cells. In general, the amount of IFN-alpha produced was significantly lower (p = 0.02) the day after transportation, although the ability to produce IFN-alpha showed a large individual variation (p < 0.001). However, both the levels of IFN-alpha produced and the decrease after transportation varied between the four parental offspring groups. Also, indications of single genes with significant effects on the ability to produce IFN-alpha were found. These results confirm a genetic influence on the ability to produce IFN-alpha. In addition, stress, such as transportation and mixing, may decrease the level of IFN-alpha produced.

Animals↗

PubMed1993

Incidence of infections in pigs bred for slaughter revealed by elevated serum levels of interferon and development of antibodies to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae.

Pigs in three specialized fattening herds were studied with respect to some immune functions, viral infections revealed by presence of interferon-alpha in serum as well as bacterial infections indicated by antibodies to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. Pigs from different breeders had signs of varying but low incidence of such infections. After transport to the fattening herds, viral infections were activated and spread during the first month, and a maximum of 19% of the pigs had signs of ongoing infections at one week. At this time, blood leukocytes prepared from the pigs had diminished ability to produce interferon-alpha in vitro. Except during the first month, serological evidence of Mycoplasma hyopneumoniae infections became gradually more frequent, and 91% of the pigs were seropositive at slaughter. Early, but not late, infections appeared to inhibit growth of the pigs as indicated by time for slaughter, but only late infections may be registered as pneumonia at slaughter. The prevalence of pigs with serological evidence of Actinobacillus pleuropneumoniae infections increased late in the fattening period, but such infections had no demonstrable impact on the time for slaughter.

Actinobacillus pleuropneumoniae↗

PubMed1993

Effects of acute physical stress on immune competence in pigs.

Some interrelations between physical stress and immune competence were studied in pigs. One group of pigs underwent 2 intense short-term treadmill exercise tests, separated by an interval of 1 week, and another group served as controls. In vitro production of interferon alpha by blood mononuclear cells and the ability of lymphocytes to proliferate and produce interleukin 2 were chosen as markers of immune competence; plasma concentrations of cortisol, lactate, and purines were used as markers of physical stress. Blood samples were drawn from a catheter in situ 60 minutes before, immediately after, and at 10, 30, and 60 minutes, and 7, 24, and 72 hours after exercise. Physical stress resulted in immediate increase in the plasma concentrations of cortisol, lactate, and hypoxanthine, but had no effect on the blastogenic capability of lymphocytes or on their interleukin-2 production on either of the test occasions. Ability of blood mononuclear cells to produce interferon alpha in vitro was not affected by exercise stress.

Animals↗

PubMed1992

Bovine virus diarrhoea virus induces in vitro a proliferative response of peripheral blood mononuclear cells from cattle immunized by infection.

The ability of bovine peripheral blood mononuclear cells (PBMC) to mount a proliferative response to bovine virus diarrhoea virus (BVDV) in vitro was examined. After culturing PBMC in the presence of a non-cytopathic strain of BVDV for 6 days, the magnitude of PBMC proliferation was measured as incorporation of radiolabelled thymidine, present during the last 18 h. Live, but not heat-inactivated, BVDV evoked a proliferative response of PBMC obtained from cattle seropositive to the virus. However, PBMC from seronegative or persistently BVDV-infected animals were not stimulated by BVDV. The presence of live BVDV did not alter the proliferative response of PBMC to stimulation with concanavalin A.

Animals↗

PubMed1992

In vitro stimulation of antibody production to Mycoplasma hyopneumoniae by porcine peripheral blood mononuclear cells.

A method to stimulate and detect the in vitro production of antibodies to Mycoplasma hyopneumoniae by porcine peripheral blood mononuclear cells (PBMC) was established. PBMC were cultured in microtiter plates coated with a sonicated M. hyopneumoniae whole cell antigen and the amount of antibody bound to the coating antigen was determined by an enzyme linked immunosorbent assay (ELISA). In addition, the amount of non-bound antibody was determined by testing the culture supernatants in the ELISA which detects porcine antibodies to M. hyopneumoniae. The production of antibodies, in terms of total absorbance values, was enhanced by including 2.5 ng pokeweed mitogen (PWM) per ml growth medium without altering the specificity of the assay. In a pilot experiment, the applicability of the method to follow the development of antigen-reactive cells during primary and secondary immunizations with M. hyopneumoniae was evaluated. Antigen-reactive cells, identified by their ability to produce antibodies to M. hyopneumoniae in vitro, were detected seven days after the primary immunization and reached their highest antigen reactivity one week later. In comparison, antigen-reactive cells could be detected three days after the booster immunization and remained in the circulation for 2 weeks.

Animals↗

PubMed1992

Interactions between immune-stimulating complexes (ISCOMs) and peritoneal mononuclear leucocytes.

Studies were undertaken in mice using immune-stimulating complexes (ISCOMs) or micelles prepared from envelope glycoproteins of human influenza virus (PR8) and matrix (i.e., ISCOM skeleton without incorporated antigen). Electron microscopic studies showed that ISCOMs, in contrast to micelles, have a remarkable affinity for cell membranes and seem to rapidly promote their own internalization by cells to which they adhere. PR8 ISCOMs, but not matrix nor micelles, significantly increased the expression of membrane Ia by peritoneal mononuclear leucocytes 24 hr after intraperitoneal immunization.

Animals↗