Pasteurella haemolytica A1 purified capsular polysaccharide does not stimulate interleukin-1 and tumor necrosis factor release by bovine monocytes and alveolar macrophages

Mannheimia haemolytica in bovine respiratory disease: immunogens, potential immunogens, and vaccines

Mannheimia haemolytica is the major cause of severe pneumonia in bovine respiratory disease (BRD). Early M. haemolytica bacterins were either ineffective or even enhanced disease in vaccinated cattle, which led to studies of the bacterium's virulence factors and potential immunogens to determine ways to improve vaccines. Studies have focused on the capsule, lipopolysaccharide, various adhesins, extracellular enzymes, outer membrane proteins, and leukotoxin (LKT) resulting in a strong database for understanding immune responses to the bacterium and production of more efficacious vaccines. The importance of immunity to LKT and to surface antigens in stimulating immunity led to studies of individual native or recombinant antigens, bacterial extracts, live-attenuated or mutant organisms, culture supernatants, combined bacterin-toxoids, outer membrane vesicles, and bacterial ghosts. Efficacy of several of these potential vaccines can be shown following experimental M. haemolytica challenge; however, efficacy in field trials is harder to determine due to the complexity of factors and etiologic agents involved in naturally occurring BRD. Studies of potential vaccines have led current commercial vaccines, which are composed primarily of culture supernatant, bacterin-toxoid, or live mutant bacteria. Several of those can be augmented experimentally by addition of recombinant LKT or outer membrane proteins.

Effects of dietary copper and molybdenum on copper status, cytokine production, and humoral immune response of calves

Twenty-four male Holstein calves were used to determine the effects of dietary Cu and Mo on performance, Cu status, and immune function of calves. Calves were fed a milk replacer that was deficient in Cu for 8 wk and then were randomly assigned after weaning to one of four treatments: 1) control (no supplemental Cu or Mo), 2) 10 mg of Cu (from CuSO4)/kg of dry matter (DM) (Cu diet), 3) 5 mg of Mo (from Na2MoO4)/kg of DM (Mo diet), or 4) 5 mg of Cu (from CuSO4) and 5 mg of Mo (from Na2MoO4)/kg of DM (Cu + Mo diet). The basal diet was a semipurified diet that contained approximately 1.1 mg of Cu and 1.1 mg of Mo/kg of DM. Calves fed the Cu and Mo diets gained weight more efficiently than those fed the control and Cu + Mo diets during the 112-d study. By d 84 of the study, calves fed the Cu diet had higher plasma Cu concentrations and plasma ceruloplasmin activities than did calves fed the other three diets and had higher liver Cu concentrations on d 136. Plasma and liver Cu concentrations did not differ among calves fed the control, Mo, and Cu + Mo diets. At d 112, activity of Cu-Zn superoxide dismutase was lower in calves fed the Mo diet than in calves fed the Cu diet. Serum total antibodies to porcine erythrocytes (primary response) were lower in calves fed the Mo diet than in calves fed the Cu diet at 7, 14, and 21 d postinoculation. Production of tumor necrosis factor and interleukin-1 by isolated peripheral blood monocytes was not significantly affected by treatment. Although no differences were apparent in plasma or liver Cu concentrations among calves fed the control, Mo, and Cu + Mo diets, calves fed the Mo diet had a more severe Cu deficiency based on depressed humoral immune response and superoxide dismutase activity.

Nitric oxide production following in vitro stimulation of ovine pulmonary alveolar macrophages

Production of inducible nitric oxide (NO) as measured by nitrite in supernatant from ovine pulmonary alveolar macrophage (PAM) cultures was assessed following stimulation of PAM with live cells and supernatants from Corynebacterium pseudotuberculosis and Pasteurella haemolytica cultures; purified bacterial lipopolysaccharide derived from both Escherichia coli and Pasteurella haemolytica alone and in combination with interferon-gamma or lymphocyte conditioned medium; or ovine lentivirus. PAM cultured ex vivo with no further stimulation for 24 h, 48 h or 72 h, produced low concentrations of NO that was not substantially increased following co-culture by the various additives. Assessment of NO production in PAM cultures containing P. haemolytica or supernatant from P. haemolytica cultures was complicated by production of high levels of nitrite in the bacterial cultures. Species differences in inducible NO production may affect the efficacy of clearance of bacterial infections and be responsible for inter-host differences in disease expression following infection by intracellular pathogens.