Studies on Pasteurella multocida : comparison of typing systems and description of certain ultrastructural features

http://www.worldcat.org/oclc/357307

Immunizing properties of lysates and sub-cellular fractions of turkey-grown Pasteurella multocida

The effects of differential centrifugation, density gradient centrifugation, freeze-thawing, and chemical lysis on the morphology of P. multocida from the blood of infected turkeys were examined by electron microscopy. The internal ultrastructure of turkey-grown cells was different from that observed previously for broth-grown P. multocida. Freeze-thawing of bacterial suspensions in sucrose resulted in partial lysis revealing bacteria in different phases of degradation. Complete lysis (but not solubilization) was effected by treatment with EDTA, lysozyme, and Triton X-100. Centrifuged lysate pellets consisted of vesicles, ranging in size from 0.05-1.0 um, that had a characteristic trilaminar membranous appearance. Various treatments on the lysate of turkey-grown Pasteurella multocida were performed to determine the nature of the cross-protection factor (CPF). No cross-protection was produced with pepsin treated lysates. Moderate cross-protection was produced with trypsin treated lysates and cross-protection was unaffected by heating the lysate at 56(DEGREES)C for 1 hour. When the lysate was centrifuged for 1 hour at 100,000 x g, CPF was found in both the supernatant and pellet fractions indicating that the CPF was polydispersed. After sucrose density gradient centrifugation, more CPF was found in the top 15-20% and bottom 50-60% bands than in the middle 30-40% band. The lytic treatment released 84.2% of the cell protein into solution and although the pellet and bottom density gradient fraction had a disproportionally small amount of protein, they had CPF equal in immunizing capacity to the whole lysate and soluble portions of the whole lysate. The effects of 9 membrane solubilizers on pelleted turkey-grown lysate were examined in an effort to release additional protein that may contain the CPF. Soluble vaccines prepared from the lysate supernatant and solubilized lysate pellet material produced varying degrees of cross-protection to a heterologous serotype challenge. Vaccines prepared from solutions containing the most protein solubilized from the pellet did not cross-protect the best. Only two preparations, the KSCN and SLS soluble vaccines, had immunizing capabilities equal to the whole lysate from turkey-grown P. multocida

Response of the ruminant respiratory tract to Mannheimia (Pasteurella) haemolytica

Pneumonia is a leading cause of loss to the sheep and cattle industry throughout the world. Mannheimia (Pasteurella) haemolytica is one of the most important respiratory pathogens of domestic ruminants and causes serious outbreaks of acute pneumonia in neonatal, weaned and growing lambs, calves, and goats.M. haemolytica is also an important cause of pneumonia in adult animals. Transportation, viral infections with agents such as infectious bovine rhinotracheitis virus, parainfluenza-3 virus or bovine respiratory syncytial virus, overcrowding, housing of neonates and weaned animals together and other stressful conditions predispose animals to M. haemolytica infection. This review assimilates some of the findings key to cellular and molecular responses of the lung from a pathologist′s perspective. It includes some of what is known and underscores areas that are not fully understood

Small, anionic, and charge-neutralizing propeptide fragments of zymogens are antimicrobial

Some inactive precursor proteins, or zymogens, contain small, amino terminus, homopolymeric regions of Asp that neutralize the cationic charge of the active protein during synthesis. After posttranslational cleavage, the anionic propeptide fragment may exhibit antimicrobial activity. To demonstrate this, ovine trypsinogen activation peptide, and frog (Xenopus laevis) PYL activation peptide, both containing homopolymeric regions of Asp, were synthesized and tested against previously described surfactant-associated anionic peptide. Peptides inhibited the growth of both gram-negative (MIC, 0.08 to 3.00 mM) and gram-positive (MIC, 0.94 to 2.67 mM) bacteria. Small, anionic, and charge-neutralizing propeptide fragments of zymogens form a new class of host-derived antimicrobial peptides important in innate defense

Antimicrobial activity of cathelicidins BMAP28, SMAP28, SMAP29, and PMAP23 against Pasteurella multocida is more broad-spectrum than host species specific

The antimicrobial activity of linear, cationic α-helical peptides from cattle (BMAP28), sheep (SMAP28 and SMAP29), and pigs (PMAP23) were assessed to determine if activity was selective for Pasteurella multocida from a particular animal species or broad-spectrum against all P. multocida tested. The antimicrobial activities of synthetic peptides were determined for P. multocida isolated from cattle (10 isolates), sheep (10 isolates), and pigs (10 isolates) in a broth microdilution assay. All thirty isolates of P. multocida were susceptible to BMAP28 (MICs and MBCs, 1.0–1.9 μM); SMAP28 and SMAP29 (MICs and MBCs, 0.2–0.7 μM); and PMAP23 (MICs and MBCs, 4.3 to ≥6.8 μM). Overall, the results of this study suggest that synthesized cathelicidins from cattle, sheep, and pigs had broad-spectrum antimicrobial activity against all P. multocida

Antimicrobial Peptides and Surfactant Proteins: Potential New Factors Against Respiratory Tract Infection

Although some vaccines and antibiotics have been very effective in preventing and treating respiratory disease, they have not been fully satisfactory. Recently, components of the innate immune system have been increasingly appreciated for their role in host defense against microbial pathogens. These molecules include lysozyme and lactoferrin, but recent work in cattle, sheep, man and other species have identified new classes of peptides expressed by respiratory epithelial cells that have potent microcidal activity in nanogram quantities. These peptides, termed antimicrobial peptides (AMP), include defensins, cathelicidins and anionic peptides. Some are expressed continuously whereas expression of others is stimulated by infection/inflammation. In calves, we have found that two AMP from the defensin family, tracheal antimicrobial peptide (TAP) and lingual antimicrobial peptide (LAP), are expressed in the newborn and increased in response to Mannheimia (Pasteurella) haemolytica infection. In contrast, sheep beta defensin-1 (SBD-1) is not induced by infection and, in fact, appears decreased during viral infection with paramyxovirus-3 (Pl-3). Decreased SBD-1 by Pl-3 may increase the lung\u27s susceptibility to secondary infections or re-infections. Other innate defense molecules include proteins released with lung surfactant. Surfactant protein A and D (SAD) can opsonize and aggregate respiratory syncytial virus (RSV) and activate alveolar macrophages. Preliminary work suggests that chronic bacterial infections result in reduced SpA and SpD expression and we are currently assessing SAD expression in response to PI-3 and RSV. A long-term goal of our work is to identify ways to up-regulate expression of AMP and/or surfactant proteins in the neonate and at times of stress in older animals in order to reduce microbial colonization. Other investigators are seeking ways to utilize AMP\u27s as a new class of antibiotics

Suppression of Mannheimia (Pasteurella) haemolytica serovar 1 infection in lambs by intrapulmonary administration of ovine antimicrobial anionic peptide

In this study, the efficacy of ovine antimicrobial anionic peptide (AP) was assessed in a lamb model of acute pneumonia. A single intratracheal dose of the peptide, H-DDDDDDD-OH (0.5 mg) reduced pulmonary inflammation and the concentration of Mannheimia (Pasteurella) haemolytica in infected lung tissue. Administration of H-DDDDDDD-OH after infection was more effective in reducing the consolidation and lesion scores at the deposition site than its administration prior to infection. Hence, the in vivo effectiveness of AP suggests that it may have applications in the treatment of pulmonary infections. Further studies are needed to confirm these findings and also to determine the optimal doses and intervals of H-DDDDDDD-OH therapy