Prevalence of antinuclear and anti-erythrocyte antibodies in healthy cats.

Background: Positive antinuclear antibody and direct antiglobulin tests support diagnoses such as systemic lupus erythematosus and immune-mediated anemia, respectively. Positive tests may occur in cats, but the prevalence of positive results in healthy cats is not well known.

Objective: The study's purpose was to determine prevalences of positive antinuclear antibody and direct antiglobulin tests in healthy cats.

Murine responses to recombinant MVA versus ALVAC vaccines against tumor-associated antigens, gp100 and 5T4.

Virally vectored cancer vaccines comprise a new form of immunotherapy that aim to generate anti-tumor immune responses with potential for tumor clearance and enhanced patient survival. Here, we compared 2 replication-deficient poxviruses modified vaccinia Ankara (MVA) and ALVAC(2) in their ability to induce antigen expression and immunogenicity of the tumor-associated antigens (TAAs) 5T4 and gp100. To facilitate the comparison, recombinant MVA-gp100M and ALVAC(2)-5T4 were constructed to complement existing ALVAC(2)-gp100M and MVA-5T4 vectors.

Serum IgG response in calves to the putative pneumonic virulence factor Gs60 of Mannheimia haemolytica A1.

Bovine pneumonic pasteurellosis vaccines incorporate various antigens of Mannheimia haemolytica, including the acknowledged virulence factor leukotoxin (Lkt), and Gs60, a surface lipoprotein. To examine the role of antibodies to Gs60 in protection, an enzyme-linked immunosorbent assay (ELISA) was developed for retrospective analysis of serum samples from previous trials in which vaccines containing native or recombinant Gs60 were administered parenterally. The analysis revealed a positive correlation between the titer of antibodies to Gs60 and protection against experimental challenge in both vaccinates and naturally exposed controls.

Expression of complement receptors 1 (CR1/CD35) and 2 (CR2/CD21), and co-signaling molecule CD19 in cattle.

C3d is a sub-fragment of the C3 component of the complement system. Covalent binding of multiple C3ds to antigen reduces the activation threshold of cognate B lymphocytes by one thousand fold through co-ligation of the B cell antigen receptor (BCR) and complement receptor 2 (CR2/CD21). Reverse transcriptase polymerase chain reaction (RT-PCR) revealed that, in cattle, four distinct complement receptors are produced from the Cr2 gene by alternative splicing.

Presence and molecular characterization of Clostridium difficile and Clostridium perfringens in intestinal compartments of healthy horses.

Background: Clostridium difficile and Clostridium perfringens are commonly associated with colitis in equids, but healthy carriers exist. Scarce information is available on the prevalence of Clostridium spp. in gastrointestinal compartments other than faeces in healthy horses, and it is unknown whether faecal samples are representative of proximal compartments.

In vivo gene expression in Mannheimia haemolytica A1 during a time-course trial in the bovine host.

The objective of this study is to examine the expression of Mannheimia haemolytica genes over time during the early stage of infection. In addition, gene expression at different sites of infection in the bovine host was examined. A time-course experiment was designed to collect pharyngeal swabs and lung washings from the same animals over two time points.

Vaccination of neonates: problem and issues.

Many serious infectious diseases occur early in life; efficacious vaccination of neonates has been a longstanding goal in both human and veterinary medicine. Efforts to immunize in the first weeks of life, in various species, have had limited success in general. This has been attributed to a combination of immaturity of the neonatal immune system and interference by maternal antibodies.

Impact of isoflupredone acetate treatment on clinical signs and weight gain in weanling heifers with experimentally induced Mannheimia haemolytica bronchopneumonia.

Objective: To characterize the impact of Mannheimia haemolytica infection on feed intake and weight gain in feedlot heifers and to evaluate the clinical efficacy of isoflupredone acetate administered in combination with oxytetracycline.

Animals: 96 weanling heifers in a research feedlot facility.

Procedures: Bronchopneumonia was induced by intrabronchial infusion of M haemolytica.

A snap-shot of Mannheimia hemolytica A1 gene expression during infection in the bovine host.

It is expected that Mannheimia hemolytica A1 expresses a particular collection of genes during infection in the host. The bacterial gene products are produced in the in vivo environment to facilitate growth and survival. Here, we examined gene expression by M.

A multivalent Mannheimia-Bibersteinia vaccine protects bighorn sheep against Mannheimia haemolytica challenge.

Bighorn sheep (BHS) are more susceptible than domestic sheep (DS) to Mannheimia haemolytica pneumonia. Although both species carry M. haemolytica as a commensal bacterium in the nasopharynx, DS carry mostly leukotoxin (Lkt)-positive strains while BHS carry Lkt-negative strains.

Oral treatment of chickens with lactobacilli influences elicitation of immune responses.

Commensal microbes in the intestine are in constant interaction with host cells and play a role in shaping the immune system. Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius are members of the chicken intestinal microbiota and have been shown to induce different cytokine profiles in mononuclear cells in vitro. The objective of the present study was to examine the effects of these bacteria individually or in combination on the induction of antibody- and cell-mediated immune responses in vivo.

Immunohistochemical investigation of cells expressing CD21, membrane IgM, CD32 and a follicular dendritic cell marker in the lymphoid tissues of neonatal calves.

Activation of B lymphocytes in the presence of passive maternal antibodies depends on expression of CD21, membrane IgM and CD32. On colligation with IgM, CD32 inhibits activation whereas CD21 enhances it. Recently, we assessed expression of CD21 and CD32 on IgM(+) cells from lymphoid tissues of newborn calves by flow cytometry, but this approach does not provide information about spatial distribution within lymphoid compartments.

Expression of complement receptor 2 (CD21), membrane IgM and the inhibitory receptor CD32 (FcgammaRIIb) in the lymphoid tissues of neonatal calves.

Limited active antibody responses in neonates following vaccination have been attributed to immaturity of the immune system and to the suppressive effects of maternal antibodies. The activating receptor CD21 (CR2), when co-ligated with membrane IgM (mIgM) by complement-bound antigen lowers the threshold for activation of B lymphocytes. The inhibitory receptor CD32 (FcgammaRII) when co-ligated with mIgM by antigen-antibody complexes raises the threshold for activation.

Variation in expression of membrane IgM, CD21 (CR2) and CD32 (Fcgamma RIIB) on bovine lymphocytes with age: a longitudinal study.

Typically, neonatal calves have poor active antibody responses to vaccination, attributed to immaturity of the neonatal immune system and suppressive effects of maternal (colostral) antibodies. Responses of naïve B cells are regulated by ligation of opposing activating (CD21, membrane IgM [mIgM]) and inhibitory (CD32) receptors. Expression of these receptors on blood lymphocytes of 15 calves, from birth to 6 months of age, was investigated by three-colour flow cytometry.

Multiple bovine FcgammaRIIb sub-isoforms generated by alternative splicing.

Receptors for the Fc portion of immunoglobulin molecules (FcR) provide an important and vital link between circulating antibody and cellular effector functions. These receptors have been well characterized in human and murine species, however few of these receptors have been investigated in livestock. FcgammaRII (CD32) is an FcR previously shown in mice and humans to exist in multiple isoforms, both activating (FcgammaRIIa, FcgammaRIIc) and inhibitory (FcgammaRIIb), on a wide variety of cells including B cells, T cells, dendritic cells, monocytes, macrophages and platelets.

Age related variation in expression of CD21 and CD32 on bovine lymphocytes: a cross-sectional study.

It is difficult to induce active immune responses in neonatal calves, partly due to limited functional ability of the immune system and partly due to immune inhibitory effects of maternal antibodies. CD21 (complement receptor 2), an activating receptor, and CD32 (Fc gamma receptor II), an inhibitory receptor, can both be expressed by mature B lymphocytes. Studies of the signalling pathways regulating B cell activation suggest that these receptors have mutually antagonistic effects, that may determine immune responsiveness in the first months of life.

Evaluation of bacteriophages for prevention and treatment of diarrhea due to experimental enterotoxigenic Escherichia coli O149 infection of pigs.

The objective of this study was to determine the efficacy of selected phages individually and in combination in prevention and treatment of diarrhea due to experimental O149:H10:F4 enterotoxigenic Escherichia coli (ETEC) in weaned pigs. For prophylaxis, the phages were administered orally shortly after challenge, and for therapeutic use, were given 24h after challenge, following the onset of diarrhea. The parameters used to assess outcomes were weight change, duration of diarrhea, severity of diarrhea, composite diarrhea score, and extent of shedding of the challenge ETEC over 6 days.

Expression of a modified Mannheimia haemolytica GS60 outer membrane lipoprotein in transgenic alfalfa for the development of an edible vaccine against bovine pneumonic pasteurellosis.

The GS60 antigen is one of the protective antigens of Mannheimia haemolytica A1. GS60 contains conserved domains belonging to the LppC family of bacterial outer membrane lipoproteins. A high antibody titer to GS60 has been shown to be significantly correlated with resistance to pneumonic pasteurellosis.

Analysis of in vivo expressed genes in Mannheimia haemolytica A1.

The expression of Mannheimia haemolytica A1 genes during in vivo growth was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) using total RNA extracted directly from M. haemolytica A1 recovered from pneumonic lungs of cattle. Primers specific for three groups of genes were used.

Cloning of a gene fragment encoding bovine complement component C3d with expression and characterization of derived fusion proteins.

The gene fragment coding for bovine C3d gene (boC3d) was cloned and expressed as a component of fusion proteins destined for use in vaccine studies in cattle, and for in vitro experiments. This fragment of complement protein C3 (C3d) has been shown to enhance B cell responses when complexed with antigen. Three potential vaccine constructs were engineered to contain one, two or three boC3d units linked to a fragment of the leukotoxin of Mannheimia haemolytica A1, an economically important pathogen of cattle that causes a fibrinous pneumonia in calves.

T lymphocyte subpopulations diverge in commercially raised chickens.

To evaluate immunocompetence in commercially raised chickens, we immunophenotyped Dekalb Delta and H&N White Leghorn (WLH) hybrids, 20 chickens in each of 3 age groups (9 wk [juvenile], 25 wk [young adult], and 79 or 80 wk [adult]), for circulating CD3+, CD4+, CD8+, TCR1+, TCR2+, and TCR3+ lymphocytes. The proportion of CD3+ T cells, including CD4+ and CD8+ subsets, was increased in the hybrids as compared with published values for laboratory-raised outbred WLH chickens. The proportion of the TCR2+ (Vbeta1) T cell subpopulation was also increased.

Passive and active components of neonatal innate immune defenses.

Innate immune defenses are crucial for survival in the first days and weeks of life. At birth, newborns are confronted with a vast array of potentially pathogenic microorganisms that were not encountered in utero. At this age, cellular components of the adaptive immune system are in a naive state and are slow to respond.

Clopidogrel induced suppression of bovine platelet activation in vitro and a preliminary study of its effect on the development of Mannheimia haemolytica induced pneumonia.

We report here on the influence of the platelet antagonist clopidogrel (Plavix) on bovine platelet function. We first evaluated the capacity of clopidogrel to inhibit adenosine diphosphate (ADP)-stimulated platelet function in the bovine species, using an ex vivo approach with blood from treated animals. Platelets isolated from treated calves displayed rapid and consistent reduction in function (aggregation, thromboxane production) upon ADP, but not platelet activating factor (PAF), stimulation.

Construction and analysis of a Mannheimia haemolytica A1 luxS mutant.

Mannheimia haemolytica A1 is the causative agent of bovine pneumonic pasteurellosis, a major cause of sickness, death, and economic loss to the feedlot cattle industry. M. haemolytica A1 produces autoinducer-2 (AI-2) like molecules that are capable of inducing quorum sensing system 2 of Vibrio harveyi.

Potential involvement of gelatinases and their inhibitors in Mannheimia haemolytica pneumonia in cattle.

Mannheimia haemolytica infection of the lower respiratory tract of cattle results in a bronchofibrinous pneumonia characterized by massive cellular influx and lung tissue remodeling and scarring. Since altered levels of gelatinases and their inhibitors have been detected in a variety of inflammatory conditions and are associated with tissue remodeling, we examined the presence of gelatinases in lesional and nonlesional lung tissue obtained from calves experimentally infected with M. haemolytica.