Efficacy of a streptomycin-dependent, live Pasteurella haemolytica vaccine against challenge exposure to Pasteurella haemolytica in cattle

A streptomycin-dependent, live Pasteurella haemolytica vaccine was given in 1 or 2 doses to 2 groups of weaned calves; 2 other groups of calves were not vaccinated. All calves in the vaccinated groups and calves in 1 of the nonvaccinated groups were stressed by transport, intratracheally inoculated with bovine herpesvirus type-1 (Cooper strain), and then intratracheally inoculated with P haemolytica type A1. The 4th group of calves (nonvaccinated controls) was not stressed and were not intratracheally inoculated with virus or bacteria. Mean daily weight gains, total clinical sign scores, lung lesion scores, plasma fibrinogen concentrations, and antibody titers against P haemolytica were determined at various intervals. Calves that had been vaccinated twice had greater mean daily weight gains and lower total clinical sign scores and lung lesion scores than did nonvaccinated, challenge-exposed calves, but the difference was not significant (P greater than 0.05). Calves vaccinated once had the greatest mean daily weight gains, the lowest total clinical sign scores, and the lowest lung lesion scores when compared with the other 2 challenge-exposed groups of calves. Mean daily weight gains and total clinical sign scores of calves vaccinated once were significantly different (P less than 0.05) than those of calves vaccinated twice. Nonvaccinated, nonchallenge-exposed control calves did not develop clinical signs of disease, did not develop lung lesions, and had consistently positive daily weight gains, and had scores in these areas that were significantly different (P less than 0.05) from those of all challenge-exposed groups of calves. Increases in plasma fibrinogen concentrations corresponded to infection with P haemolytica.(ABSTRACT TRUNCATED AT 250 WORDS)     

A crude cytotoxin vaccine protects sheep against experimental Pasteurella haemolytica serotype A2 infection

Three vaccines containing Pasteurella haemolytica serotype A2 antigens were tested for their ability to protect sheep against a homologous challenge. A crude cytotoxin preparation in combination with a sodium salicylate extract (SSE) or crude cytotoxin alone were highly protective (98 and 86%, respectively), whereas SSE alone was poorly (47%) protective. These findings indicated that the crude cytotoxin was an essential component of a protective vaccine. Protection correlated with serum cytotoxin-neutralising (CN) titres and bactericidal activity, which were stimulated by antigens in the crude cytotoxin preparation.     

Investigation of outer membrane proteins of Pasteurella. 2: Iron-regulated outer membrane proteins of Pasteurella multocida and Pasteurella haemolytica

Pasteurella multocida and Pasteurella haemolytica produce specific proteins in the outer membrane under iron-depleted conditions. Pasteurella multocida serovar A expresses these proteins of molecular masses of 76 and 96 kDa as determined by electrophoresis. The analogous serovar D produces a further iron-regulated protein of 85 kDa. The Pasteurella haemolytica strains of serovar A1, A6 and T contain iron-regulated outer membrane proteins of molecular masses of 71, 77 and 100 kDa. These proteins possess binding positions for iron ions. Both Pasteurella multocida and Pasteurella haemolytica strains utilize iron from porcine and bovine transferrin, but not from haemin and haemoglobin.     

Identification of immunogenic, surface-exposed outer membrane proteins of Pasteurella haemolytica serotype 1

Pasteurella haemolytica serotype 1 (S1) is the bacterium most frequently recovered from the lungs of cattle that have succumbed to shipping fever pneumonia. P. haemolytica outer membrane proteins (OMPs) are important immunogens in the development of resistance to pneumonic pasteurellosis. The purpose of this study was to identify the repertoire of immunogenic, surface-exposed P. haemolytica (S1) OMPs, that could be important in the development of protective immunity. We determined surface exposure of OMPs by (1) their susceptibility to protease treatment and (2) their ability to adsorb out antibodies from bovine immune sera. For a comprehensive identification of immunogenic, surface-exposed OMPs, we used bovine antisera from calves that were resistant to experimental P. haemolytica challenge after (1) natural exposure to P. haemolytica, (2) vaccination with live P. haemolytica, or (3) vaccination with P. haemolytica OMPs. We identified 21 immunogenic, surface-exposed P. haemolytica OMPs. Most were recognized by all three immune sera. However, some were recognized by one or two of the three antisera. Our analyses identified surface-exposed, immunogenic proteins that were not identified in previous studies.     

A stochastic partial-budget analysis of an experimental Pasteurella haemolytica feedlot vaccine trial

A field trial compared a modified Pasteurella haemolytica biotype A serotype 1 leukotoxin vaccine to a commercial vaccine during March-July 1995 in a Natal Midlands, South African, feedlot. Weaners/long weaners purchased by the feedlot were allocated systematically into test vaccine and control vaccine groups of 1241 and 1240 head, respectively, and fed in groups of approximately 200 head. Morbidity and mortality were monitored until the animals were marketed. Details of pleuritis and pneumonia at veterinary meat inspection were recorded for 409 test-vaccinated and 424 control-vaccinated cattle. An increase in morbidity but not mortality risk of respiratory disease was shown between test (13.8% morbidity) and control (11.4% morbidity) groups. Cattle with a processing weight <245 kg were 1.4 times more likely to develop respiratory diseases than cattle with a processing weight > or =245 kg. Cattle bought on auction were 1.6 times more likely to develop respiratory disease than cattle bought at private sales. A partial farm budget incorporating Latin Hypercube sampling of uncertain variables was done to obtain the distribution of possible financial outcomes if the test vaccine were used. Impact (sensitivity) analyses indicated that median weight of carcass cut away had the greatest impact on the profit margin. The partial farm budget highlighted the importance of reducing sub-clinical lesions in a feedlot.     

Efficacy of an inactivated recombinant vaccine encoding a fimbrial protein of Pasteurella multocida B:2 against hemorrhagic septicemia in goats

This study was carried out to determine the antibody responses and protective capacity of an inactivated recombinant vaccine expressing the fimbrial protein of Pasteurella multocida B:2 following intranasal vaccination against hemorrhagic septicemia in goats. Goats were vaccinated intranasal with 10⁶ CFU/mL of the recombinant vaccine (vaccinated group) and 10⁶ CFU/mL of pET32/LIC vector without fimbrial protein (control group). All three groups were kept separated before all goats in the three groups were challenged with 10⁹ CFU/mL of live pathogenic P. multocida B:2. During the course of study, both serum and lung lavage fluid were collected to evaluate the antibody levels via enzyme-linked immunosorbent assay. It was found that goats immunized with the inactivated recombinant vaccine developed a strong and significantly (p < 0.05) higher specific IgA and IgG responses in both serum and lung lavage fluid samples compared to the control and unvaccinated groups. Following intratracheal challenge, the rate of isolation was 17% for the vaccinated group, 67% for the control group and 100% for the unvaccinated group. However, none of the goat from the vaccinated group had P. multocida B:2 in the liver, tonsil and heart. Therefore, the study revealed that an inactivated recombinant vaccine significantly provides significant protection against high dose challenge and enhances the stimulation of the local and systemic immunities.     

Efficacy of sulbactam-ampicillin in an induced Pasteurella haemolytica pneumonia model in calves

Therapeutic efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin was evaluated in an ampicillin-resistant Pasteurella haemolytica pneumonia model in cattle, using an IV agar emboli method of infection. Groups of cattle given vehicle (group 1, n = 19) or ampicillin (group 2, n = 8) had 74% and 50% mortality, respectively, whereas group 3 (n = 11) given sulbactam-ampicillin had no mortality. Morbidities were 100% in groups 1 and 2 and 27% in group 3. Retrospectively, mortalities and morbidities were significantly (P less than 0.001) lower for group 3 given sulbactam-ampicillin when compared with those in groups 1 and 2 given vehicle or ampicillin, respectively. Evidence of embolic pneumonic pasteurellosis was observed histologically.     

An outbreak of Pasteurella multocida pneumonia in lambs during a field trial of a vaccine against Pasteurella haemolytica

A vaccine against pneumonic pasteurellosis was evaluated for efficacy at two dilutions in lambs transported by sea from New Zealand to Saudi Arabia. The experimental vaccine was a killed Pasteurella haemolytica serotype A1 and A2 preparation. There was no evidence of either dilution of the vaccine leading to a lower pneumonia death or lesion rate than for the control group. However, bacteriological examinations to establish the causality of the pneumonia cases showed Pasteurella multocida to be the dominant organism, while P. haemolytica types A1 and/or A2 occurred at only a very low incidence.     

Failure of an Actinomyces pyogenes vaccine to protect sheep against an intravenous challenge

The immunity conferred by an A. pyogenes bacterin-toxoid was evaluated in sheep, using an intravenous challenge system. Three sheep were vaccinated and 3 served as controls. The vaccinated sheep were not protected against pyogenic conditions. High antitoxin levels were induced by vaccination but could not be associated with protection against infection. Antibacterial antibody levels elicited with initial vaccination dropped progressively with the 2nd and 3rd vaccinations. Nevertheless, these antibodies did not seem to be necessary for protection against A. pyogenes conditions.     

禽多杀性巴氏杆菌C48—1成熟外膜蛋白H重组亚单位疫苗免疫效果的研究

将融合表达禽多杀性巴氏杆菌成熟外膜蛋白H（OmpmH）的重组菌pGEX—ompmH／BL21大量培养，在最佳诱导条件下诱导表达，表达产物经蛋白酶剪切及亲和层析纯化，得到OmpmH基因的原核表达产物，将其与弗氏完全佐剂混合制成油乳剂亚单位疫苗，用该疫苗肌肉注射接种5周龄鸡，首免后每周采血检测抗体，二免后第2周用10LD50禽多杀性巴氏杆菌强毒菌株C48-1进行攻击。结果显示，OmpmH具有良好的免疫原性，能诱导鸡体产生特异性抗体，可抵抗强毒菌株C48-1的致死性攻击，免疫效果优于禽多杀性巴氏杆菌弱毒疫苗。     

Characterization and comparison of antimicrobial susceptibilities and outer membrane protein and plasmid DNA profiles of Pasteurella haemolytica and certain other members of the genus Pasteurella.

The outer membrane protein (OMP), plasmid, and antimicrobial resistance profiles of Pasteurella haemolytica serotypes 1 through 12, a bovine isolate of P multocida, a chicken isolate of P multocida, and an unidentified Pasteurella species of bovine origin were examined. Isolates of P haemolytica serotypes belonging to the same biotype possessed similar OMP profiles. Biotype A isolates contained 2 prominent OMP of 43 kilodaltons (kD) and 29 kD, whereas biotype-T serotypes contained 3 major OMP of 43, 36, and 25 kD. The major OMP profiles of the 2 P multocida isolates and the unidentified Pasteurella species were different from each other and from P haemolytica isolates. Plasmid DNA screening indicated both plasmid-containing and plasmid-free P haemolytica and P multocida isolates. Multiple drug resistance was found in pasteurellae isolates with and without plasmids. However, a relationship between drug resistance and plasmid isolation was found in 3 of 4 haemolytica serotype 1 field isolates, all of which contained a 2.51-megadalton plasmid and had multiple drug resistance for benzylpenicillin, ampicillin, streptomycin, and tetracycline.     

In vitro assessment of the efficacy of erythromycin in combination with oxytetracycline or spectinomycin against Pasteurella haemolytica

The effects of combining erythromycin (Ery) with oxytetracycline (Oxy) or spectinomycin (Sp) on Pasteurella haemolytica were evaluated in vitro using the chessboard (checkerboard) technique. These combinations were selected because all are drugs widely used in bovine respiratory disease treatment, and they represent possible sequential or complementary mechanisms of action. Using the recommended breakpoints of greater than 4 micrograms/ml for Ery, 16 micrograms/ml for Oxy, and 32 micrograms/ml for Sp, of the 33 P. haemolytica isolates, 32 were resistant to Oxy, 27 to Sp, and 14 to Ery. Based on the fractional inhibitory concentration index, Ery and Oxy in combination were synergistic or additive against 32 of 33 isolates. The combination of Ery and Sp was synergistic or additive against 27 of 33 isolates. No instances of antagonism were seen. When the effects were considered within the context of therapeutically achievable serum/tissue concentrations, the effects of Ery and Oxy in combination were only marginal. Thus, against P. haemolytica isolates, Ery and Sp appeared to represent an effective antimicrobial combination, whereas Ery and Oxy were only of marginal efficacy as a combination.     

禽源多杀性巴氏杆菌重组外膜蛋白A间接ELISA方法的建立

为建立基于重组外膜蛋白A的检测禽源多杀性巴氏杆菌抗体的间接ELISA方法,扩增去除信号肽的外膜蛋白A(outer membrane protein A,OmpA)基因,定向克隆到载体pET32a,构建重组表达质粒pET32a-PmOmpA,转化至Escherichia coli BL21(DE3)以IPTG进行诱导,通过镍离子亲和层析纯化重组蛋白,进行SDS-PAGE和Westernblotting分析。以重组蛋白为包被抗原建立间接ELISA方法,方阵滴定法确定其最佳包被浓度和血清的最佳稀释度。结果,重组蛋白能与阳性血清发生良好的免疫反应。重组蛋白的包被浓度为4mg/L,血清的最佳稀释度为1∶80。SPF鸡的新城疫、鸡白痢和大肠杆菌病阳性血清,隔离饲养的番鸭鸭瘟、鸭病毒性肝炎和鸭疫里默氏菌病阳性血清,用该方法检测均为阴性。板内变异系数和板间变异系数均小于10%。ELISA方法的敏感性比直接凝集试验高出80倍以上。以重组外膜蛋白A建立的ELISA方法具有良好的特异性、重复性和敏感性,可以用于禽霍乱感染性抗体的检测,也可用于禽霍乱灭活苗和荚膜疫苗免疫效果的检测。     

Comparison of single strains of four serotypes of Pasteurella haemolytica biotype A in experimental pneumonia of sheep

Single strains of serotypes A1, A2, A7 and A9 of Pasteurella haemolytica were separately used in combination with Mycoplasma ovipneumoniae to reproduce pneumonia. Macroscopically and microscopically the pneumonias associated with individual serotypes were similar and it is concluded that serotypes of P haemolytica isolated with low frequency in field disease may be equally virulent to common serotypes.     

Comparison of antibody responses in cattle to outer membrane proteins from Pasteurella haemolytica serotype 1 and from eight untypeable strains.

Membrane associated proteins from 8 untypeable Pasteurella haemolytica strains were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and compared with those of P haemolytica serotypes 1 and 2. Cattle antisera obtained from P haemolytica serotype 1 vaccine trials were used in immunoblotting assays to compare the membrane proteins from the 8 untypeable strains with those from P haemolytica serotypes 1 and 2. Densitometry was used to identify bands, and using linear regression analyses, the peak area optical densities (measuring antibody response) were correlated to lesion scores from the vaccinated calves. Significant antibody responses to proteins of 99, 69, 60, 55, 47, 45, 39, 33, 30, 16, and 14.5 kDa were detected for 4 or more of the 8 P haemolytica untypeable strains. Serotypes 1 and 2 of P haemolytica contained a comigrating 30-kDa protein. Antibody responses to proteins of 39, 33, and 32.5 kDa were significant for 3 of the untypeable strains and had significant correlation to lesion scores. Antibody responses to various other proteins were significant for 2 untypeable strains each.     

Comparison of pathophysiologic changes in the lungs of calves challenge exposed with Escherichia coli-derived endotoxin and Pasteurella haemolytica, alone or in combination

Pulmonary responses to intratracheal challenge exposure with Pasteurella haemolytica, with or without Escherichia coli-derived endotoxin, E coli endotoxin alone, or saline solution were compared in anesthetized, mechanically ventilated neonatal calves. Baseline values for dynamic compliance, total pulmonary resistance, functional residual capacity, arterial blood gas tensions, hemogram, leukogram, and systemic and pulmonary arterial pressures were recorded for each calf. After baseline data were obtained, calves were challenge exposed with logarithmic-growth phase P haemolytica organisms with or without E coli endotoxin, E coli endotoxin alone, or saline solution (0.9% NaCl). Physiologic data were obtained immediately after challenge exposure and at various intervals over the next 6 hours. Calves challenge exposed with P haemolytica alone developed sever hypoxemia, had increased alveolar-arterial oxygen difference and threefold increases in total pulmonary resistance, became hypercarbic, had decreased functional residual capacity, and developed systemic hypotension without change in pulmonary arterial pressure. At necropsy, these calves had extensive multifocal areas of necrohemorrhagic and purulent pneumonia. Ratio of extravascular lung water to lung dry weight was not significantly increased in lung specimens obtained from calves challenge exposed with P haemolytica, but ratio of lung wet weight to dry weight was increased, indicating that increased lung wet weight was attributable largely to increased solids and not to fluid alone. (Extravascular lung water measurement excludes fluid from the vascular compartment.) Intratracheal challenge exposure with endotoxin failed to alter lung function and caused minor changes in lung structure consisting of focal areas of hemorrhage and edema.(ABSTRACT TRUNCATED AT 250 WORDS)