Pasteurella Multocida Capsular Type Research Articles

Protective Efficacy of Calcium Phosphate Nanoparticle Adsorbed Bivalent Subunit Vaccine of Pasteurella multocida against Homologous Challenge in Mice

Background: Swine pasteurellosis, caused by Pasteurella multocida capsular types A and D, causes heavy economic loss to the pig farmers. The vaccine presently used is a bacterin of Pasteurella multocida capsular type B that is proven to be effective against bovine pasteurellosis. However, its efficacy against swine pasteurellosis is questionable. Methods: The present study was carried out to evaluate the efficacy of calcium phosphate nanoparticle adjuvanted bivalent subunit vaccine prepared from Pasteurella multocida capsular types A and D along with a monovalent subunit vaccine prepared from Pasteurella multocida capsular type B in mice. The Alum precipitated bacterin vaccine was used as the control. Result: The bivalent subunit vaccine showed significantly higher serum IgG response than either of the other two vaccines. The calcium phosphate nanoparticle adjuvanted vaccines could elicit 100% protection in mice against homologous challenges but the aluminum hydroxide adjuvanted bacterin vaccine could not elicit significant protection. Based on this preliminary work, it was concluded that the bivalent subunit vaccine would be a better option for immunization of swine against swine pasteurellosis.

Evaluation of the Frequency of Swine Enzootic Pneumonia in one Farm Based on Slaughterhouse, Clinical and Laboratory Monitoring

Background: Swine enzootic pneumonia (SEP), caused by the bacterium Mycoplasma hyopneumoniae, is one of the main respiratory diseases of pigs. The purpose of this study was to evaluate the frequency of SEP in one farm with an independent production system, low level of technification and high losses in the meat packing plant, based on slaughterhouse, clinical and laboratory monitoring.Materials, Methods & Results: This study consisted of three monitoring steps, divided into three periods: P1, P2 and P3. In the first step of the study, slaughterhouse reports were analyzed and slaughtering was monitored at one meatpacking plant in Santa Maria, RS, Brazil. The second step of the study started by drawing up a profile of the farm that supplied the pigs to the aforementioned slaughterhouse, after which clinical monitoring was performed on three occasions. The third step of the study (laboratory monitoring) involved collecting lung fragments containing suspected SEP lesions from the meatpacking plant and subjecting them analysis. The average measured enzootic pneumonia (EP) in P3 was 38.54% (P < 0.05) higher than in P1 and 29.79 higher than in P2. The mean frequency of pulmonary emphysema (PE) in P3 was 59.13% (P < 0.05) higher than in P1 and 48.04% higher than in P2. The mean number of lung adhesions (LA) did not differ statistically (P > 0.05) between P1, P2 and P3. As for the mean frequency of pulmonary hepatization (PH), P3 was 48.80% higher (P < 0.05) than P1 and 41.78% higher than P2. With regard to the mean frequency of craniodorsal lung lesions (CLL), P3 was 48.26% higher (P < 0.05) than P1 and 40.77% higher than P2. The mean frequency of disseminated lesions (DL) and the pneumonia severity index (PSI) showed no statistical difference (P > 0.05) between the three evaluated periods. On the other hand, in the finishing period (FP), the frequency of coughing and sneezing was 37.56% (P < 0.05) higher in P1 than in P3. The frequency of coughing and sneezing evaluated in the nursery phase (CF) did not differ (P > 0.05) between periods. The samples sent to the laboratory MicroVet tested positive for M. hyopneumoniae, Influenza virus and Pasteurella multocida capsular type A. In the samples sent to the laboratory LABAC, the mean PCRmo (PCR for identification of mollicutes) did not differ (P > 0.05) in the analyzed periods, although the presence of DNA from bacteria of the class Mollicutes was confirmed in the fragments. In addition, the mean results of PCRmy (PCR for identification of M. hyopneumoniae) also did not differ (P > 0.05), although they revealed positivity for M. hyopneumoniae. Discussion: In relationship to the mean frequency of PE in each analyzed period, our study revealed an increase in the number of pulmonary lesions at slaughter during the periods under analysis. This finding is in agreement with those of other authors, who explain that pneumonias is one of the main health problems for swine producers. Some lesions are identified more frequently in routine inspections in meatpacking plants, including pulmonary emphysema, lung adhesions and pneumonia caused by M. hyopneumoniae. In our study, we found that the clinical signs of respiratory distress decline between the periods under evaluation, but during slaughter, the lesions suggestive of SEP continued to show an upward trend, mainly because they were chronic. Other authors state that several control measures should be adopted to ensure good zootechnical indices, including vaccination, strategic medication and the reduction of risk factors, thereby minimizing the level of M. hyopneumoniae infection in the herd.

Differences in pathogenicity and virulence-associated gene expression among Pasteurella multocida strains with high and low virulence in a lung tissue model

Pasteurella multocida capsular type A can cause a pulmonary infection, leading to serious pecuniary losses in cattle. The heterogeneity of infection outcome of P. multocida strains showing different virulence may be related to divergent expression of virulence genes. In this study, we compared the transcriptional response of virulence-associated genes in high (PMPAN001) and low (PMPAN007) virulence P. multocida capsular type A strains in lung tissues and in vitro. These clinical isolates differ in their organ bacterial loads, mRNA abundance of the same virulence genes between lung and culture medium, and extent of lung damage. Among the eight virulence-associated genes (fimA, tbpA, exbD, fur, oma87, pmHAS, nanH, and tonB), seven genes showed higher expression in lung compared with in vitro at 16 h (P ≤ 0.05) in PMPAN001, but not in PMPAN007. FimA, exbD, fur, oma87, pmHAS, and tonB gene transcripts showed significantly higher expression in PMPAN001 than in PMPAN007 in the lung tissues at 16 h post-infection (P ≤ 0.05). Specially, the virulence gene, nanH, in both strains was associated with poor expression in vitro and lung tissue (mean relative mRNA abundance values < 0.6). Strain PMPAN001 had a higher proliferation rate in vivo than strain PMPAN007. The bacterial loads of PMPAN001 in the organs increased from 12 h post-infection, with maximum bacteria count ranging from 1 million to 20 million/mg. In addition, lungs treated with PMPAN001 produced serious and extensive lesions marked with inflammation at 20 h. Overall, our results reveal that the highly expressed virulence-associated genes, fimA, exbD, fur, oma87, pmHAS, and tonB can be used as markers for assessing the virulence of P. multocida capsular type A strains.

Complete Genome Sequence of a Novel T7-Like Bacteriophage from a Pasteurella multocida Capsular Type A Isolate.

A novel virulent bacteriophage, vB_PmuP_PHB02 (phage PHB02), infecting Pasteurella multocida capsular type A strains, was isolated from wastewater from a swine farm in China. Phage PHB02 has a linear double-stranded DNA genome consisting of 38,670 base pairs (bp), with a G+C content of 40.8% and a 127-bp terminal redundancy. Forty-eight putative open reading frames were identified, and no transfer RNA-encoding genes were detected. The morphology and genomic structure of phage PHB02 resemble those of T7-like phages belonging to the family Podoviridae, of the order Caudovirales. Phage PHB02 was stable over a wide range of temperatures (4-50°C) and pH values (5.0-9.0), and lysed 30 of the 31 capsular-type-A P. multocida strains tested. Phage PHB02 had no effect on other bacterial species or on P. multocida strains belonging to capsular types D or F.

Effect on immune response against Pasteurella multocida capsular type a:1 and a:4 on supplementation with protein purified derivatives of Mycobacterium bovis in chicken

Effect on immune response against Pasteurella multocida capsular type a:1 and a:4 on supplementation with protein purified derivatives of Mycobacterium bovis in chicken

High and low-virulent bovine Pasteurella multocida capsular type A isolates exhibit different virulence gene expression patterns in vitro and in vivo

Pasteurella multocida capsular type A causes respiratory disease in cattle. P. multocida virulence gene expression patterns, especially among different virulent isolates, during in vitro and in vivo growth are poorly understood. Here we show that the highly virulent bovine P. multocida capsular type A isolate PmCQ2 exhibits a significantly higher growth rate in mice, as compared with a strain of lower virulence, P. multocida capsular type A isolate PmCQ6. Among the six known and potential virulence genes (ompA, ompH, pfhB2, hasR, pm0979, and pm0442) investigated, most genes were expressed more highly in both isolates when grown in vivo as compared with in vitro, with ompH and pm0442 having the highest magnitude of expression. Virulence gene expression was higher in PmCQ6 than in PmCQ2 during in vitro growth. However, in mice, most virulence genes were expressed more highly in PmCQ2 as compared with PmCQ6. Virulence gene expression was highest in the liver and lowest in the lung, but was uncorrelated to bacterial loads. This study indicates that individual pathogenic capacity of P. multocida isolates is associated with the virulence gene expression patterns in vivo growth but not in vitro, and the investigation of virulence gene expression in pathogen should be performed in vivo.

Endophytic fungi from tropical ethnoveterinary plants and their antibacterial efficacy against Pasteurella multocida Capsular Type A strain.

Pasteurella multocida is an important veterinary pathogen causing infections in animals and birds. Nowadays, different reports have described the severity of infections, increasing resistance of micro-organisms to antibiotics, and the contribution of ethnoveterinary practices towards the treatment of various ailments of animals. The aim of the present study was to investigate the antibacterial efficacy of the ethanolic extracts of endophytic fungi against P. multocida Capsular Type A strains. A total of six endophytic fungi were isolated from two tropical ethnoveterinary plants: Garcinia xanthochymus H. and Polygonum chinense L. The ethanolic extracts of the endophytic fungi were subjected to in vitro antimicrobial activity by the well diffusion method. Besides, we evaluated the treatment of mice with the potent fungal extract and observed the effects in different organs under electron microscopy. Our results showed that four fungi had antimicrobial activity against the selected pathogen. The best antibacterial activity was showed by the extract of the endophytic fungi, Glomerella magna isolated from G. xanthochymus, with a minimum inhibitory concentration of 46.9 μg/mL and minimum bactericidal concentration of 750 μg/mL. Treatment of mice with the potent fungal extract caused a considerable inhibitory effect on the pathogen growth in vital organs, results that was also confirmed by histopathological studies made by scanning electron microscopy. The present findings indicated that the endophytic fungi G. magna has the potential to provide an effective treatment against infections caused by Pasteurella multocida. However, the isolation of bioactive components needs further investigation.

Comparative Genomics Analysis of Two Different Virulent Bovine Pasteurella multocida Isolates.

The Pasteurella multocida capsular type A isolates can cause pneumonia and bovine respiratory disease (BRD). In this study, comparative genomics analysis was carried out to identify the virulence genes in two different virulent P. multocida capsular type A isolates (high virulent PmCQ2 and low virulent PmCQ6). The draft genome sequence of PmCQ2 is 2.32 Mbp and contains 2,002 protein-coding genes, 9 insertion sequence (IS) elements, and 1 prophage region. The draft genome sequence of PmCQ6 is 2.29 Mbp and contains 1,970 protein-coding genes, 2 IS elements, and 3 prophage regions. The genome alignment analysis revealed that the genome similarity between PmCQ2 and PmCQ6 is 99% with high colinearity. To identify the candidate genes responsible for virulence, the PmCQ2 and PmCQ6 were compared together with that of the published genomes of high virulent Pm36950 and PmHN06 and avirulent Pm3480 and Pm70 (capsular type F). Five genes and two insertion sequences are identified in high virulent strains but not in low virulent or avirulent strains. These results indicated that these genes or insertion sequences might be responsible for the virulence of P. multocida, providing prospective candidates for further studies on the pathogenesis and the host-pathogen interactions of P. multocida.

Experimental Study of the Pathogenicity of Pasteurella multocida Capsular Type B in Rabbits

The increased frequency of isolation of Pasteurella multocida capsular type B from rabbitries in north-western India prompted this investigation into the role of this organism in inducing disease in rabbits. Ten rabbits were divided into two groups of five animals. Group I rabbits were infected intranasally (IN) with 1ml of inoculum containing 2×10(5) colony forming units/ml, while rabbits in group II were given 1ml phosphate buffered saline IN. The rabbits in group I developed respiratory distress, increased rectal temperature and severe dyspnoea, with death occurring 24-48h post infection. The main pathological findings were severe congestion and haemorrhage in the trachea, fibrinopurulent pneumonia, bacteraemia and septicaemia. The nasal secretions of all group I animals contained P. multocida. These observations indicate that in addition to P. multocida capsular types A and D, P. multocida capsular type B can also be highly pathogenic for rabbits.

Pathological and molecular diagnosis of Swine Pasteurellosis in pigs of Chhattisgarh, India

Outbreak of swine pasteurellosis with 66% mortality rate was studied in a pig population of Raipur, Durg and Rajnandgaon districts of Chhattisgarh, India. Affected animals exhibited pyrexia, dullness, staggering gait, anorexia, serous nasal discharge and dyspnoea. External lesions exhibited by affected pigs were oedematous swellings in the pharyngeal region and serous to seropurulent nasal discharge. Gross lesions observed were consolidation and haemorrhages in lungs, petechial to echymotic haemorrhages on serous membranes, oedema and haemorrhages in lymph nodes. On histopathological examination, lungs showed typical fibrinous bronchopneumonia with multifocal suppuration. Pleura were severely thickened. Heart of some pigs showed presence of thrombi, haemorrhages and degeneration of myocardium. The blood smears from heart blood and tissue impression smears revealed bipolar organisms indicating the presence of Pasteurella spp. Growth, phenotypic and molecular characterization of the isolated organism revealed the presence of Pasteurella multocida capsular type B.

Outbreaks of pleuritis and peritonitis in calves associated with Pasteurella multocida capsular type B strain

CASE HISTORY: Three dairy calf-rearing properties experienced high mortality in calves during 2008 and 2009. Affected calves were aged 13–18 weeks (Farm I), 6 months (Farm II), and 2–11 weeks (Farm III), and the mortality rate was 22/175 (13%), 5/80 (6%), and 60/900 (7%), respectively. CLINICAL AND LABORATORY FINDINGS: Affected calves rapidly became moribund, were in respiratory distress, and had a fever (40–41°C). Post-mortem examination of nine calves revealed fibrinopurulent pleuritis, pericarditis, and peritonitis. This was confirmed histopathologically on tissues from three calves, one from each farm; aggregates of small Gram-negative coccobacilli were evident on Gram stain. Pasteurella multocida was cultured from tissues from affected calves on the three farms, and PCR of DNA extracted from tissue samples amplified cap-sular type B-specific DNA. Multi-locus sequence typing (MLST) demonstrated that all capsular type B isolates belonged to the same sequence type (ST), ST62, but did not belong to serotype B:2, the only B serotype classified as causing haemorrhagic septicaemia by the Office International des Épizooties (OIE). DIAGNOSIS: Pleuritis and peritonitis due to infection with P. multocida capsular type B strain. CLINICAL RELEVANCE: Haemorrhagic septicaemia was excluded as a cause of disease from the three farms, however P. multocida was the primary agent in the affected calves. It is possible the agent has been present in New Zealand for some time but not reported, as there had been no transfer of animals between affected farms. Emergence of the syndrome could potentially be a result of factors other than just the presence of the organism, such as changing management. The syndrome described may be of increasing importance in the future.