Atrophic rhinitis in swine: correlation of Pasteurella multocida pathogenicity with membrane protein and lipopolysaccharide patterns

CXCL8 Knockout: A Key to Resisting Pasteurella multocida Toxin-Induced Cytotoxicity

Pasteurella multocida, a zoonotic pathogen that produces a 146-kDa modular toxin (PMT), causes progressive atrophic rhinitis with severe turbinate bone degradation in pigs. However, its mechanism of cytotoxicity remains unclear. In this study, we expressed PMT, purified it in a prokaryotic expression system, and found that it killed PK15 cells. The host factor CXCL8 was significantly upregulated among the differentially expressed genes in a transcriptome sequencing analysis and qPCR verification. We constructed a CXCL8-knockout cell line with a CRISPR/Cas9 system and found that CXCL8 knockout significantly increased resistance to PMT-induced cell apoptosis. CXCL8 knockout impaired the cleavage efficiency of apoptosis-related proteins, including Caspase3, Caspase8, and PARP1, as demonstrated with Western blot. In conclusion, these findings establish that CXCL8 facilitates PMT-induced PK15 cell death, which involves apoptotic pathways; this observation documents that CXCL8 plays a key role in PMT-induced PK15 cell death.

Acute phase responses induced in dwarf goats by r.BolL(-1beta), r.BolL(-2) and r.BolFN(-gamma)

The contribution of each of the pro-inflammatory cytokines to specific components of the host response to infection remains unclear. Therefore, the effects of single doses of cytokines were studied in dwarf goats. The present study was carried out to investigate the effects of r.BoIL(-1beta), r.BoIL(-2) and r.BoIFN(-gamma) on plasma zinc and iron concentrations, white blood cell counts, and body temperature. The i.v. injection of r.BolL(-1beta) (1 mug kg(-1)) resulted in an immediate fever which reached peak values 45 and 180 min after injection. Compared with fever induced by r.BoIL(-1beta), that caused by r.BoIFN(-gamma) (2 mug kg(-1)) was delayed in onset. Although the biphasic fever after r.BoIFN(-gamma) was more pronounced than after r.BoIL(-1beta), the reduction in plasma trace metal concentrations was less than after r.BoIL(-1beta), r.BoIL(-2) (1 mug kg(-1) i.v.) did not induce changes in these parameters. The haematologic changes observed revealed a cell type and cytokine specific pattern. The delayed onset of the effects induced by IFN(-gamma) suggests that they may be mediated through the induction of other mediators of inflammation.

Pasteurella multocidaand bovine respiratory disease

Pasteurella multocidais a pathogenic Gram-negative bacterium that has been classified into three subspecies, five capsular serogroups and 16 serotypes.P. multocidaserogroup A isolates are bovine nasopharyngeal commensals, bovine pathogens and common isolates from bovine respiratory disease (BRD), both enzootic calf pneumonia of young dairy calves and shipping fever of weaned, stressed beef cattle.P. multocidaA:3 is the most common serotype isolated from BRD, and these isolates have limited heterogeneity based on outer membrane protein (OMP) profiles and ribotyping. Development ofP. multocida-induced pneumonia is associated with environmental and stress factors such as shipping, co-mingling, and overcrowding as well as concurrent or predisposing viral or bacterial infections. Lung lesions consist of an acute to subacute bronchopneumonia that may or may not have an associated pleuritis. Numerous virulence or potential virulence factors have been described for bovine respiratory isolates including adherence and colonization factors, iron-regulated and acquisition proteins, extracellular enzymes such as neuraminidase, lipopolysaccharide, polysaccharide capsule and a variety of OMPs. Immunity of cattle against respiratory pasteurellosis is poorly understood; however, high serum antibodies to OMPs appear to be important for enhancing resistance to the bacterium. Currently availableP. multocidavaccines for use in cattle are predominately traditional bacterins and a live streptomycin-dependent mutant. The field efficacy of these vaccines is not well documented in the literature.

Diagnostic and typing options for investigating diseases associated with Pasteurella multocida

Pasteurella multocida is responsible for major animal diseases of economic significance in both developed and developing countries whereas human infections related to this bacterium are infrequent. Significantly, development of a carrier status or latent infections plays a critical role in the epidemiology of these diseases. Aiming at increased knowledge of these infections, we examine potential diagnostic and selected typing systems for investigating diseases caused by P. multocida. Detection of P. multocida from clinical specimen by; (i) isolation and identification, (ii) polymerase chain reaction (PCR), iii) specific hybridisation probes, (iv) serological tests and (v) other alternative methods is critically evaluated. These detection systems provide a wide spectrum of options for rapid diagnosis and for detecting and understanding of latent infections in herd/flock health control programmes, though PCR methods for detecting P. multocida in clinical specimen appear increasingly preferred. For establishing the clonality of outbreak strains, we select to discuss macromolecular profiling, serotyping, biotyping, restriction enzyme analysis, ribotyping and multiplex PCR typing. Although P. multocida infections can be rapidly diagnosed with molecular and serological tests, isolation and accurate species identification are central to epidemiological tracing of outbreak strains. Our review brings together comprehensive and essential information that may be adapted for confirming diagnosis and determining the molecular epidemiology of diseases associated with P. multocida.

Subcellular distribution of Plp-40, a lipoprotein in a serotype A strain of Pasteurella multocida

A 40-kDa lipoprotein (Plp-40) is expressed by serotype A strains of Pasteurella multocida in amounts which correlate with the amount of capsular material present. We hypothesized that Plp-40 is exposed at the outer surface of the outer membrane (OM) of the cell and is associated with the serotype A exopolysaccharide material. The objectives of the present study were to confirm the lipoprotein nature of Plp-40 and to determine its subcellular location. Plp-40 maturation was shown to be sensitive to globomycin, thereby confirming it to be a bacterial lipoprotein. Plp-40 was shown to be present in the OM fractions of P. multocida obtained by both sarkosyl extraction and sucrose density gradient centrifugation, as well as in capsule fractions obtained by either hyaluronidase treatment or warm buffer extraction. [(3)H]palmitic acid-labeled Plp-40 could be removed from the surface of whole cells by exposure to proteinase K. Autoradiography of (125)I-labeled cell surface proteins exhibited a 40-kDa band that was prominent in capsulated strains and greatly diminished in a noncapsulated strain. These results support the hypothesis that Plp-40 is a lipid-modified OM protein, which is exposed on the outer cell surface and is likely associated with serotype A extracellular polysaccharide.

Characterisation of bovine strains of Pasteurella multocida and comparison with isolates of avian, ovine and porcine origin

One hundred and fifty-three bovine Pasteurella multocida strains recovered primarily from cases of pneumonia and mastitis in England and Wales over an 11-year period were characterised by capsular PCR typing, comparison of outer membrane protein (OMP) profiles, and multilocus sequence analysis. All of the strains were of capsular type A with the exception of a single capsular type F isolate. Thirteen distinct OMP profiles (OMP-types) were identified based mainly on molecular mass heterogeneity of the heat-modifiable (OmpA) and porin (OmpH) proteins. However, 85% of the isolates were represented by just five OMP-types and 39% of the strains were of a single OMP-type. Multilocus sequence analysis revealed a limited degree of genetic diversity among bovine P. multocida isolates; strains of the same OMP-type have identical genetic backgrounds and represent distinct clones. Analysis of OMP variation was more discriminating than multilocus sequence analysis because strains of different OMP-types had the same, or similar, genetic backgrounds. The association of a small number of clones with the majority of cases of bovine pneumonia suggests that these clones have an increased capacity to cause disease compared to less frequently recovered clones. Molecular mass heterogeneity of OmpA and OmpH, in strains of the same or similar genetic background, suggests that these proteins are subject to diversifying selection within the host and might play important roles in host-pathogen interactions. Comparison of the OMP profiles of bovine isolates with those of avian, ovine and porcine strains showed that a high proportion of the respiratory tract infections in each of these species are caused by different strains of P. multocida. However, the presence of small numbers of closely related strains in more than one host species suggests that transmission of bacteria between different host species is also a factor in the population biology of P. multocida.

Characterization and comparison of Pasteurella multocida strains associated with porcine pneumonia and atrophic rhinitis

One hundred and fifty-eight porcine strains of Pasteurella multocida, recovered primarily from cases of pneumonic pasteurellosis or progressive atrophic rhinitis (PAR) in England and Wales, were characterized by determination of their capsular types, presence or absence of the toxA gene and molecular mass heterogeneity of the heat-modifiable (OmpA) and porin (OmpH) proteins. Eighteen groups (clones) of strains were identified on the basis of specific combinations of capsular type, toxA status and outer-membrane protein (OMP)-type. The data provided evidence that different subpopulations of P. multocida are responsible for pneumonia and PAR in pigs. The majority (88 %) of cases of pneumonia were associated exclusively with non-toxigenic capsular type A strains of OMP-types 1.1, 2.1, 3.1 and 5.1 and capsular type D isolates of OMP-type 6.1. These strains were recovered from widespread geographical locations within England and Wales over a 12-year period and represented mostly single sporadic cases. The association of a small number of P. multocida variants with the majority of cases of porcine pneumonia suggests that these strains are not opportunistic pathogens of low virulence but represent primary pathogens with a relatively high degree of virulence. In contrast, the majority (76 %) of cases of PAR were associated with toxA-containing capsular type D strains of OMP-type 4.1 and capsular type A and D strains of OMP-type 6.1. Toxigenic capsular type A strains associated with PAR and non-toxigenic capsular type A strains associated with pneumonia represent distinct subpopulations of P. multocida that can be differentiated by their OMP-types. The association of capsular types A and D with strains of the same OMP-types, and the absence and presence of the toxA gene in strains of the same OMP-types, suggest that horizontal transfer of capsular biosynthesis and toxA genes has occurred between strains representing certain subpopulations of P. multocida.

Interactions between bovine endothelial cells and Pasteurella multocida: association and invasion

We investigated the association and the invasion of a bovine aortic endothelial cell (BAEC) line by Pasteurella multocida to study the potential role of internalized bacteria and possible intracellular survival during Pasteurella infections. Our data indicate that P. multocida is able to adhere to and to invade BAECs. The density of the bacterial population plays a defined role for an optimal mechanism of interaction between bacteria and cells, as does the incubation period of association and invasion. The optimal bacteria/cells ratio was found to be 100/1, while the optimal infection time was approximately 4 h of incubation. Bacterial internalization was dependent on microfilament and microtubule stability. The invasion ability of P. multocida in the presence of cytochalasin D was reduced by 60%; in the presence of colchicine it was reduced by 97% and in the presence of nocodazole it was reduced by 95%. Our data show that internalized P. multocida did not induce mortality of invaded endothelial cells. Some Pasteurella cells were able to survive and undergo exocytosis.

Role of Pasteurella multocida, Pasteurella haemolytica and Salmonella typhimurium porins on inducible nitric oxide release by murine macrophages

The aim of this study was to verify whether Pasteurella haemolytica, P. multocida and Salmonella typhimurium porins could affect the inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release by murine resident peritoneal macrophages in vitro. We also compared their effect with that elicited by P. haemolytica, P. multocida and S. typhimurium lipopolysaccharide (LPS) whose biological activity is well known. Variations in NO release and iNOS mRNA expression due to variable concentrations of porins were recorded and compared. We also investigated the synergism between bacterial products and interferon gamma (IFN-gamma). With this aim cells were incubated with porins together with murine rIFN-gamma prior to assessing the presence of NO in the supernatant and mRNA analysis. Porins in themselves were not able to induce NO release by resident peritoneal macrophages. Incubation of macrophages with IFN-gamma in the presence of porins increased NO release, whereas incubation in the presence of the arginine analog N(G)-monomethyl-L-arginine (NMA) inhibited NO release. The greatest NO release was obtained using porins at a concentration of 5 microg/mL. Porins, together with IFN-gamma, were also able to upregulate the mRNA expression of iNOS. Our findings suggest that gram-negative porins are able to modulate inflammatory and immunological responses by affecting the release of NO and the expression of iNOS gene in activated macrophages.

Role of Pasteurella multocida porin on cytokine expression and release by murine splenocytes

The aim of this study was to verify whether Pasteurella multocida porin can affect the expression and release of IL-1alpha, IL-6, TNF-alpha, IL-4, IFN-gamma, IL-10 and IL-12 by murine splenocytes in vitro. P. multocida porin and lipopolysaccharide (LPS) were able to induce the release of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 in a dose-dependent fashion. The greatest release of these cytokines was obtained using P. multocida porin at a concentration of 5 microg ml(-1) and LPS at a concentration of 1 microg ml(-1). The time-courses of release showed that P. multocida LPS was able to stimulate the production of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 earlier than porin and at a greater rate. No effect was observed on IL-4 and IL-10 release under the same experimental conditions. P. multocida porin and LPS were also able to up-regulate the mRNA expression of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 p40. Our findings suggest that P. multocida porin is able to modulate inflammatory and immunological responses by affecting the release of several cytokines and the expression of their genes.

Adaptive acquisition of novobiocin resistance in Pasteurella multocida strains of avian origin

Naturally occurring strains of Pasteurella multocida are atypically susceptible to hydrophobic antibiotics such as novobiocin, despite their Gram-negative cell envelope ultrastructure. Four strains adaptively resistant to 1000 micrograms/ml of novobiocin were obtained by sequentially subculturing cell surface hydrophobic variants of avian origin in the presence of increasing antibiotic concentrations. Adaptive novobiocin resistance was accompanied in all cases by the concomitant acquisition of resistance to coumermycin, a hydrophobic antibiotic possessing the same mechanism of action, but not to the functionally disparate hydrophobic antibiotic rifamycin. The acquisition of resistance was not accompanied by alterations in the lipid composition of the cell envelope. Subsequent growth of adaptively resistant strains in the absence of novobiocin did not result in the restoration of susceptibility to either novobiocin or coumermycin. Acquisition of adaptive resistance in encapsulated parental strains resulted in an inability to synthesize capsular material and enhanced cell surface hydrophobicity; however, parental encapsulation and decreased cell surface hydrophobicity were restored upon removal of novobiocin. These data suggest that acquisition of adaptive resistance to novobiocin conferred in this manner is the result of a stable genetic event affecting the mechanistic target of both novobiocin and coumermycin rather than a physiological adaptation involving outer membrane impermeability.

Immunogenicity of purified lipopolysaccharide or protein-oligosaccharide conjugates of Pasteurella multocida type 6:B in mice

Purified lipopolysaccharide (LPS) of Pasteurella multocida type 6:B, while toxic at higher doses, was protective at lower dose levels against experimentally-induced pasteurellosis in mice. However, the observed protection was abrogated if such LPS was digested with proteinase K prior to use in immunisation. The O-antigen polysaccharide side-chain (OS) of LPS did not appear to contribute to the observed protection as judged by the fact that immunisation of mice with purified OS or OS-protein conjugates, all of which were nontoxic, failed to confer protection against challenge with homologous virulent organisms. This was despite generation of significant levels of OS-specific antibodies, predominantly either of the IgM or IgG isotypes, in immunised mice.

Cloning and characterization of the major outer membrane protein gene (ompH) of Pasteurella multocida X-73

The major outer membrane protein (OmpH) of Pasteurella multocida X-73 was purified by selective extraction with detergents, followed by size exclusion chromatography. The planar lipid bilayer assay showed that OmpH has pore-forming function. The average single channel conductance in 1.0 M KCl was 0.62 nS. The gene (ompH) encoding OmpH has been isolated and sequenced by construction of a genomic library and PCR techniques. The coding region of this gene is 1,059 bp long. The predicted primary protein is composed of 353 amino acids, with a 20-amino-acid signal peptide. The mature protein is composed of 333 amino acids with a molecular mass of 36.665 kDa. The ompH gene encoding mature protein has been expressed in Escherichia coli by using a regulatable expression system. The ompH gene was distributed among 15 P. multocida serotypes and strain CU. Protection studies showed that OmpH was able to induce homologous protection in chickens. These findings demonstrate that OmpH is a protective outer membrane porin of strain X-73 and is conserved among P. multocida somatic serotypes.

Outer membrane proteins of bovine Pasteurella multocida serogroup A isolates

The outer membrane proteins (OMPs) of P. multocida serotypes A3 (7 isolates), A4 (2 isolates), A3,4 and A2 (one isolate each) obtained from pneumonic cattle (10 isolates) and from one pig isolate were investigated to identify potential immunogens. SDS-PAGE of P. multocida OM isolated by SDG centrifugation of spheroplasts revealed eight major OMPs. Outer membranes isolated by sarcosyl extraction or SDG had similar protein composition on Coomassie blue-stained SDS-PA gel and on immunoblots. Two major OMPs (M(r)s of 35 and 46 kDa at 100 degrees C) demonstrated heat modifiability with apparent M(r)s of 30 and 34 kDa at 37 degrees C, respectively. The N-terminal aa sequences of these heat modifiable proteins revealed homology with E. coli OmpA and Hib P1 proteins, respectively. Protease treatment of whole cells followed by western immunoblots using bovine convalescent sera identified several immunogenic, surface-exposed and conserved OMPs among the eleven P. multocida isolates examined. The whole organism SDS-PAGE profiles of the eleven P. multocida isolates differed such that six patterns were seen. These patterns could potentially be used as a typing system for P. multocida bovine isolates based on the molecular weights of whole cell proteins. The above observations have potentially important implications relative to the immunity to infection.

Passive immune cross-protection in mice produced by rabbit antisera against different serotypes of Pasteurella multocida

Haemorrhagic septicaemia (HS) and fowl cholera (FC) are specific diseases caused by certain serotypes of Pasteurella multocida. Strains that usually cause HS in cattle and water buffalo do not produce FC in avian species, and strains that cause FC do not produce HS in cattle and water buffalo. A variety of P. multocida serotypes, including unusual strains which can cause HS in wild ruminants, were evaluated in passive immune protection studies to determine the immunological relationship between strains associated with HS and FC. Various degrees of cross-protection were seen among the strains. Antiserum against a serotype B:3,4 strain protected against strains capable of causing HS (serotypes B:1, B:2, B:3,4, B:4 and E:2) and FC (serotypes A:1, A:3 and A:5). Antiserum against an FC strain (serotype A:5) similarly protected against strains capable of causing HS and FC. Antigenic analyses indicated that cross-protection was not necessarily induced by serotype-specific capsular (beta) or somatic (gamma) antigens or major porin protein. SDS-PAGE and immunoblots of whole cell lysates of the different HS and FC strains showed many protein-staining bands with similar mobilities and antigenic activity. These cross-reactive antigenic bands occurred in the 20- to 120-kDa range. Adsorption of antiserum with a heterologous serotype removed its reactivity with most of these bands, as well as its ability to cross-protect.

Biochemical characterization of lipopolysaccharides extracted from a hydrophobic strain of Pasteurella multocida

Lipopolysaccharides were extracted from freeze-dried cells of Pasteurella multocida strain P-1581 (serotype 8) by the phenol-chloroform-petroleum ether method and biochemically analysed using standard procedures. The primary neutral sugars were glucose, galactose and heptose. No deoxy sugars were detected. Amino sugars included galactosamine, glucosamine and glucosamine-6-phosphate. 3-Deoxy-D-manno-2-octulosonic acid was present at a relatively low concentration. The analyses included identification and quantification of phosphate and alanine. The primary fatty acids and their approximate relative ratios were 3-hydroxytetradecanoate and tetradecanoate 2:1. Tetradecanoic acid was bound almost exclusively by ester linkages. 3-Hydroxytetradecanoic acid was bound primarily by amide linkages, although significant numbers of ester-bound residues were noted. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analyses indicated that the lipopolysaccharides were of low molecular weight.

The 32 kDa major outer-membrane protein of Pasteurella multocida capsular serotype D

The major outer-membrane protein (MOMP) of Pasteurella multocida serotype D strain P210, with an apparent molecular mass of 32 kDa, was purified and characterized. The purification method involved selective extraction of MOMP with N-lauroylsarcosine and SDS, followed by immunoaffinity chromatography using a murine monoclonal antibody (mAb). The N-terminal sequence and amino acid composition of the MOMP showed considerable similarity to other Gram-negative bacterial porins, notably to the 37 kDa MOMP (porin H) of P. multocida. Immunoelectron microscopy and colony blotting assays were used to demonstrate the surface localization of the 32 kDa MOMP on bacterial cells. The colony blotting assay provided a simple, sensitive and rapid screening method for visualizing accessibility of the antibody on the cells. In a Western blot assay, murine polyclonal hyperimmune serum against the purified 32 kDa MOMP recognized both serotype B and D strains bearing either a 32 kDa or a 37 kDa MOMP, whereas the mAb recognized only serotype D strains bearing a 32 kDa but not a 37 kDa MOMP. The present data indicate that the 32 kDa MOMPs of P. multocida are antigenically heterogeneous and possess both specific and cross-reacting epitopes. Detection of type-specific epitopes on the 32 kDa MOMP using an mAb may have potential implications regarding the feasibility of developing a serotyping system for P. multocida.

Identification and characterization of outer membrane proteins of Pasteurella multocida serotype D by using monoclonal antibodies

Monoclonal antibodies (MAbs) against Pasteurella multocida serotype D were obtained by fusion of spleen cells from BALB/c mice immunized with outer membrane proteins (OMPs) with SP2/0-Ag 14 murine myeloma cells. Desirable MAbs were selected by enzyme-linked immunosorbent assay (ELISA) with OMP as the antigen. MAbs MT1 and MT2 identified two different proteins (H [heavy] and W [weak]), each with a molecular mass of 32 kDa, in Western blots (immunoblots). Treatment of the OMPs with proteolytic enzymes and sodium periodate indicated that the binding sites of MAbs MT1 and MT2 are of protein and glycoprotein natures, respectively. The epitopes reactive with MAbs were surface exposed, as visualized by immunoelectron microscopy. Among field isolates of P. multocida serotype D, two distinct OMP patterns were recognized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and these patterns were designated types I and II. In both the ELISA and the Western blot, MAb MT1 recognized only type I isolates, whereas MAb MT2 recognized both type I and II isolates. Neither MAb MT1 nor MAb MT2 reacted with either reference strains of capsular serotypes A, B, E, and F or field isolates of capsular serotype A of P. multocida. This is the first report of MAbs identifying the serotype D-specific OMP of P. multocida.

Isolation and partial characterization of the major protein of the outer membrane of Pasteurella haemolytica and Pasteurella multocida

The N-terminal amino acid sequence of the 35 kDa (p35) major outer membrane protein (MOMP) of P. multocida shared a strong homology with those of homotrimeric nonspecific porins of gram-negative bacteria. The capacity of outer membrane protein (OMP) preparations of P. multocida to bind to respiratory mucosal surface preparations was inhibited significantly by using a polyclonal anti-p35 antiserum in an adhesion ELISA. Anti-p35 antiserum cross-reacted with a 44 kDa (p44) MOMP of P. haemolytica. N-terminal sequencing of MOMP p44 revealed a homology of 81% with the putative porin MOMP p35 of P. multocida.

Cloning and expression of two Pasteurella multocida genes in Escherichia coli

A library of cloned Pasteurella multocida (toxigenic strain 9222, serotype D2) genomic sequences was constructed in Escherichia coli by incorporating TaqI digestion fragments into the plasmid vector pUC19. Immunological screening with antibodies directed against porin H, the major protein of the P multocida outer membrane, allowed the identification of a recombinant plasmid containing a 2.9-kbp DNA insert. This plasmid encoded the synthesis of two polypeptides, p25 (25 kDa) and p28 (28 kDa) which were detected in the different compartments of the E coli transformant. The peptide p25 was more abundant in the periplasm whereas p28 was mainly found in the cell envelope and in the cytosol. Immunological analysis indicates that p25, in contrast to p28, is antigenically related to porin H of P multocida. The expression in E coli of the gene encoding p28 was enhanced by induction of the lac promoter.

Immunogens of Pasteurella

The family Pasteurellaceae Pohl contains Gram-negative, facultatively anaerobic and fermentative bacteria of the genera Pasteurella, Haemophilus, and Actinobacillus. Approximately 20 different species of the genus Pasteurella have been identified using phenotypic and genetic analyses. Of these species, P. multocida and P. haemolytica are the most prominent pathogens in domestic animals causing severe diseases and major economic losses in the cattle, swine, sheep, and poultry industries. Mechanisms of immunity to these bacteria have been difficult to determine, and efficacious vaccines have been a challenge to develop and evaluate. Pasteurella multocida of serogroups A and D are mainly responsible for disease in North American poultry and pigs and to a lesser extent in cattle. Fowl cholera in chickens and turkeys is caused by various serotypes of P. multocida serogroup A and characterized by acute septicemia and fibrinous pneumonia or chronic fibrinopurulent inflammation of various tissues. Current biologicals in use are live P. multocida vaccines and bacterins. Potency tests for avian P. multocida biologicals are a bacterial colony count for vaccines and vaccination and challenge of birds for bacterins. Somatic antigens, particularly lipopolysaccharide (LPS), appear to be of major importance in immunity. In North American cattle, P. multocida serogroup A is associated mainly with bronchopneumonia (enzootic pneumonia) in young calves; however, it is occasionally isolated from fibrinous pleuropneumonia of feedlot cattle (shipping fever). Biologicals currently available are modified-live vaccines and bacterins. The potency test for vaccines is bacterial colony counts. The test for bacterin potency is vaccination and challenge of mice. Important immunogens have not been well characterized for P. multocida infection in cattle. In swine, P. multocida infection is sometimes associated with pneumonia; however, its major importance is in atrophic rhinitis. A protein toxin (dermonecrotic toxin), produced by toxigenic strains of P. multocida types A and D, and concurrent infection with Bordetella bronchiseptica appear to be the major factors in development of atrophic rhinitis. Currently available biologicals are bacterins and inactivated toxins (toxoids). The toxin appears to be the major immunogen for preventing atrophic rhinitis. There are, however, no standardized requirements for potency testing of P. multocida type D toxoid. Various serotypes of P. haemolytica biotype A are responsible for severe fibrinous pleuropneumonia of cattle and sheep, occasionally septicemia of lambs, and mastitis in ewes. Several serotypes of P. haemolytica biotype T are isolated from acute septicemia of lambs. The currently available P. haemolytica biologicals are modified-live vaccines, bacterins, bacterial surface extracts, and culture supernates that contain an exotoxin (leukotoxin).(ABSTRACT TRUNCATED AT 400 WORDS)

Immunobiology of Acinetobacter baumannii and genospecies 3

Five representative, taxonomically and serologically defined clinical isolates of Acinetobacter baumannii and genospecies 3, and A. baumannii strain ATCC 19606 were examined for immunogenicity in rabbits following experimental bacteremia. All rabbits seroconverted as determined with the aid of the tube O-agglutination, indirect hemagglutination, and enzyme-linked immunosorbent assay (ELISA) procedures. Immunoblots detected over twenty immunogenic, proteinase-K-degradable polypeptide antigens in trichloroacetic acid extracts, outer membrane protein fractions, and mechanically disrupted (type MM2 mixer drill) cell preparations. Sodium periodate-susceptible phenol-water and phenol-chloroform-light petroleum lipopolysaccharide (LPS) extracts proved to be immunogenic for the rabbits as well. Convalescent sera from two patients with documented bacteremia due to genospecies 3, serovar 4, likewise revealed numerous anti-polypeptide and anti-LPS antibodies comprising the immunoglobulin G (IgG) and the IgM class.

Purification and characterization of protein H, the major porin of Pasteurella multocida

Protein H (B. Lugtenberg, R. van Boxtel, D. Evenberg, M. de Jong, P. Storm, and J. Frik, Infect. Immun. 52:175-182, 1986) is the major polypeptide of the outer membrane of Pasteurella multocida, a bacterium pathogenic for humans and animals. We have purified this protein to homogeneity by size exclusion chromatography after selective extraction with surfactants and demonstrated its pore-forming ability after reincorporation into planar lipid bilayers. In these experiments, the current through the pores was a linear function of the applied voltage in the range of -50 to +50 mV. Voltages beyond +/- 50 mV tended to partially close the channels, giving rise to apparent negative resistances. These observations suggest that protein H channels are probably not voltage regulated in vivo. With the patch clamp technique, single-channel conductance fluctuations of 0.33 nS were recorded in 1 M KCl. Electrophoretic and circular dichroism analyses showed that protein H forms homotrimers stable in sodium dodecyl sulfate at room temperature, with a high content of beta-sheet secondary structure. Upon boiling, the trimers were fully dissociated into monomers with an increase of alpha helix and irregular structure, at the expense of beta sheets. The apparent molecular mass of fully denatured monomers ranged between 37 and 41.8 kDa, depending on the electrophoretic system used for analysis. The trimeric arrangement of protein H was confirmed by image analysis of negatively stained, two-dimensional crystal arrays. This morphological study revealed, in agreement with electrophoretical data, a trimeric structure with an overall diameter of 7.7 nm. Each monomer appeared to contain a pore with an average diameter of 1 nm. Quantitative comparisons revealed that the amino acid composition (hydropathy index of -0.40) and the N-terminal sequence (determined over 36 residues) of protein H are similar to those of bacterial general porins, notably porin P2 of Haemophilus influenzae. We conclude from this set of structural and functional data that protein H of P. multocida is a pore-forming protein related to the superfamily of the nonspecific bacterial porins.

Enhanced adherence of Pasteurella multocida to porcine tracheal rings preinfected with Bordetella bronchiseptica

Adherence of 25 isolates of Pasteurella multocida to porcine tracheal rings was evaluated. Results indicated that adherence was not related to the isolate's origin, capsular or somatic types, dermonecrotoxin production or hemagglutination activity. The effect of a preinfection with Bordetella bronchiseptica on the colonization by P. multocida was then studied. On rings infected with P. multocida alone, bacteria initially adhered to the epithelium, but within a few hours, the level of colonization decreased progressively. On rings preinfected with B. bronchiseptica, or pretreated with a cell-free B. bronchiseptica culture supernate (or filtrate), a high level of P. multocida colonization was maintained for at least 24 hours. Results indicate that B. bronchiseptica appears to facilitate upper respiratory tract colonization by P. multocida by a process which involves a low molecular weight (less than or equal to 1000) heat-stable substance, possibly the tracheal cytotoxin.

Cell surface characteristics and virulence in mice of Pasteurella multocida

The virulence of three avian strains of Pasteurella multocida was evaluated in mice. Strains P-1059I (serotype A:3) and its uncapsulated variant P-1059B and strain 2723 (serotype A:16) were compared. Capsular material thickness after polycationic ferritin labelling of dextrose starch agar (DSA)-grown P. multocida was shown to vary with the strain and was not always related to virulence. Addition of alpha,alpha' bipyridyl (BIP) (160 microM) to the culture medium did not affect capsule production but increased virulence of strains P-1059B and 2723. None of the strains tested showed dermonecrotic activity. Using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), outer membrane protein (OMP) profiles indicated for strains P-1059I and P-1059B three proteins of 30, 35, and 38 KDa with the 30 KDa protein being the major one. Strain 2723 showed the same OMP profile but the 38 KDa protein was the major one. DSA + BIP-grown strains showed the same OMP profiles. Whole cell profiles were similar for all strains tested. However, addition of BIP to the culture media increased the virulence of strains P-1059B and 2723 and for all strains a 39 KDa protein was induced by the iron chelator. The results indicate that encapsulation may be important for virulence, but other surface components such as OMPs may be required as well.

In vitro binding of Pasteurella multocida cell wall preparations to tracheal mucus of cattle and swine and to a tracheal epithel cell wall preparation of cattle

Outer membrane preparations of various Pasteurella isolates (Pasteurella multocida and some other Pasteurella species) from cattle and swine were extracted by N-lauryl-sarcosine sodium salt. Capsular extracts were prepared by heat treatment. Both preparations bound to epithel cell wall preparations (ECW) of trachea from cattle and to tracheal mucus of cattle and swine. Binding was demonstrated by an enzyme-linked immunosorbent assay (ELISA). Distinct high adherence values were shown by the greater part of membrane preparations of mucoid Pasteurella strains, especially when originating from cattle.

Purification of rough-type lipopolysaccharides of Neisseria meningitidis from cells and outer membrane vesicles in spent media

A procedure for the purification of Neisseria meningitidis lipopolysaccharide (LPS) from outer membrane vesicles (OMV) in spent growth media was developed. Five different LPS strains of group A N. meningitidis were grown in tryptic soy broth with vigorous aeration for 36-48 h, and centrifuged to collect both cells and supernatants. The amount of LPS in the OMV in the supernatants was higher or at least equal to that in the cells. The OMV in each supernatant were concentrated, pelleted by ultracentrifugation, and treated with 2% sodium deoxycholate to dissociate LPS from OMV. The LPS was then separated from capsular polysaccharides, proteins and phospholipids by gel filtration on Sephacryl S-300 column in 1% sodium deoxycholate, and precipitated from the column fractions in 70% ethanol. In addition, LPS was also extracted from cells with hot phenol-water, ultracentrifuged once after treatment with ribonuclease, and purified on Sephacryl S-300. When compared with an improved phenol-water extraction method, the LPS obtained from either OMV or cells by the above methods gave a 40-180% increase in yield. The LPS also had much higher activities in limulus amebocyte lysate assay, rabbit pyrogenic test, and enzyme-linked immunosorbent assay. The LPS purified from cells and from OMV were indistinguishable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis.

Restriction endonuclease analysis of porcine Pasteurella multocida isolates from Quebec

We have used restriction endonuclease analysis (REA) of genomic DNA to classify porcine Pasteurella multocida isolates with similar capsular and somatic serotypes, and to monitor the distribution of isolates from 12 different herds in Quebec. Within herds, P. multocida isolates of similar capsular and somatic serotypes showed similar REA fingerprints. Between herds, some isolates had similar REA fingerprints. However, differences in REA enabled subtyping of many P. multocida isolates with the same antigen types. Our data indicate that REA would enable accurate epidemiological typing of P. multocida in conjunction with classical capsular and somatic typing.

Comparisons of Pasteurella multocida lipopolysaccharides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to determine relationship between group B and E hemorrhagic septicemia strains and serologically related group A strains

Lipopolysaccharides (LPSs) purified from 16 reference somatic serotypes of Pasteurella multocida were examined and compared by discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Resolution of LPS patterns in a gel was optimum when sample wells were cast separately from the stacking gel and the running gel consisted of 15% T (total monomer) polyacrylamide and 4 M deionized urea. Band patterns of P. multocida LPSs in a gel differed from control Salmonella minnesota wild-type and core mutant LPSs. Although the band patterns and mobilities of LPSs from some P. multocida reference serotypes were similar, none were identical. Evidence for O antigens similar to those produced by enterobacteria was not observed. Proteinase K digestion of whole P. multocida cells resulted in LPS band patterns similar to those of purified LPS. The presence or absence of a capsule on a strain had no major influence on band patterns in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Comparisons of LPS patterns of group B and E hemorrhagic septicemia strains with those of serologically related group A strains of P. multocida indicated that they were similar. Typing antisera made with purified serotype 2 or 5 LPS reacted with electroblots of all these strains. However, the reactions did not distinguish strains as being serotype 2 or 5.

Development and epidemiological applications of a bacteriophage typing system for typing Pasteurella multocida

A bacteriophage typing system was developed for typing toxigenic and nontoxigenic strains of Pasteurella multocida. A phage set of 24 phages with different lytic spectra was isolated after mitomycin treatment of P. multocida strains, isolated mainly from pigs from herds with atrophic rhinitis. On a test set of 97 different strains isolated from pigs, these 24 phages were able to type 87% of the strains. The 97 test strains could be subdivided into 31 different types by reaction with the 24 phages. The reproducibility after subculture and storage of the strains was good (95%). Phage typing of 217 toxigenic P. multocida field isolates from 37 pig herds predominately with clinically atrophic rhinitis resulted in 18 different phage types and an overall typability of 68%. Of 24 herds from which more than three isolates of toxigenic P. multocida were obtained, a single phage type was demonstrated in 5 herds, while in 9 herds a single phage type represented at least half of the isolates. The phage types in the remaining 10 herds revealed no dominating phage type. The phage typing system described appears to be a valuable epidemiological tool for studying the spread of P. multocida.

Susceptibility to hydrophobic molecules and phospholipid composition in Pasteurella multocida and Actinobacillus lignieresii

Despite its typically gram-negative cell envelope ultrastructure, Pasteurella multocida is susceptible to the hydrophobic antibiotic novobiocin and is unable to initiate growth on MacConkey agar, a parameter often used to effect is differentiation from other members of the family Pasteurellaceae such as Actinobacillus lignieresii. However, growth on basal medium supplemented with individual selective factors and an agar diffusion assay revealed the bile salts contained in MacConkey agar to be toxic to both organisms. Four P. multocida surface hydrophobicity variants exhibited consistent in vitro susceptibility to the hydrophobic antibiotics novobiocin, rifamycin SV, and actinomycin D as determined by broth dilution. Readily extractable lipid fractions were obtained by chloroform-methanol extraction of freeze-dried whole cells from exponential-phase cultures. No major differences in total cellular readily extractable lipid content were observed among the P. multocida and A. lignieresii strains examined, although hydrophobic P. multocida strains appeared to contain slightly more than did hydrophilic strains. Analytical thin-layer chromatography and quantitation of resolved readily extractable lipid components revealed the major cell envelope phospholipids of both organisms to be phosphatidylethanolamine and phosphatidylglycerol in a molar ratio of approximately 4:1 regardless of cell surface hydrophobicity properties. Similar results were obtained for Pseudomonas aeruginosa, which is notably refractory to hydrophobic molecules. These data support the conclusion that the permeability of the P. multocida cell envelope to structurally unrelated, hydrophobic molecules is not dependent on cell surface hydrophobicity and cannot be explained on the basis of anomalous polar lipid composition.

Atrophic rhinitis: antibiotic treatment

Atrophic rhinitis is a term used to describe a rare nasal infection. Although it does not have a fatal outcome, cause osteomyelitis, or produce pain, it does induce bilateral nasal obstruction and a persistent foul odor of which the subject and others are painfully aware. The organism most often associated with atrophic rhinitis is Klebsiella ozenae. Antibiotic susceptibility patterns of this microorganism have made treatment with orally administered antibiotics difficult. K ozenae was cultured from the nasal cavity of three patients. Two patients were treated for two weeks with tobramycin (MIC, 4 micrograms/ml; 4 mg/kg/day). Odor decreased in one patient, but K ozenae failed to clear. In the second patient both odor and K ozenae disappeared. The third patient was treated for 1 week with tobramycin (MIC, 4 micrograms/ml; 4 mg/kg/day); odor decreased, but K ozenae could still be cultured. She was treated for an additional 2 weeks with topical gentamicin (MIC, 0.5 micrograms/ml) with disappearance of both odor and K ozenae. Intravenous aminoglycoside may be helpful in treating atrophic rhinitis, but topical aminoglycoside may provide an effective and cheaper form of treatment.

Immunotype epitopes of Neisseria meningitidis lipooligosaccharide types 1 through 8

Lipooligosaccharides (LOS) of the eight immunotypes found in serogroup B Neisseria meningitidis were purified from their prototype strains grown in tryptic soy broth. Rabbit antisera to these LOS were prepared. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining revealed that most of the LOS antigens contained two major components; the larger components had apparent molecular weights (Mrs) in the range of 4,800 +/- 300, and the smaller components had an apparent Mr of 4,300. Immunoblot analysis showed that the larger major component of an LOS, in general, was much more immunogenic because the rabbits produced antibodies exclusively or primarily to this component even though the LOS immunogen contained both large and small major components. Antibodies to the smaller 4,300-Mr components were infrequently observed but, when present, were cross-reactive with the same-size components of all heterologous LOS. Hence, the immunotype epitopes reside in the larger major components of all immunotypes except type 5, in which a smaller major component having an apparent Mr of 4,400 carries the epitope. Rabbit antisera to types 1, 5, and 6 were immunotype specific. Antisera to other types had cross-reactivities with some heterologous LOS, and the larger components, but not the 4,300-Mr components, of the LOS were primarily responsible for the cross-reactivities. This finding suggests that the larger components of cross-reactive LOS have a similar structure in addition to their type-specific sugar moieties. The LOS of N. meningitidis M986, a strain used for the production of a serotype 2a vaccine, was found to contain the immunotype 7 epitope.

Hemagglutination by Pasteurella multocida of porcine origin

A total of 25 fresh isolates of Pasteurella multocida from pigs were tested for the ability to agglutinate erythrocytes of different origins. Of the 18 isolates from pigs with atrophic rhinitis (AR), 8 (44%) agglutinated human type O erythrocytes, whereas none of the 7 isolates from pigs without AR did so. Hemagglutination was mannose sensitive, and the activity was destroyed by heating and by trypsinization but was not affected by formaldehyde treatment or by homogenization of bacterial cells. The other 14 erythrocyte species tested, including human types A and B, were not agglutinated by P. multocida. The present study provides evidence that certain P. multocida isolates from pigs with AR possess a mannose-sensitive hemagglutinin.

A method for purification of bacterial R-type lipopolysaccharides (lipooligosaccharides)

A new gel filtration method was developed for purification of R-type lipopolysaccharides (lipooligosaccharides) from some nonenteric gram-negative bacteria, including Neisseria meningitidis, Haemophilus influenzae, and Bordetella pertussis. These wild-type lipooligosaccharides are poorly extractable by the phenol-chloroform-ether extraction method of C. Galanos, O. Luderitz, and O. Westphal [1969) Eur. J. Biochem. 9, 245-249) and therefore a new procedure was developed for their isolation. The lipooligosaccharides (LOS) were first extracted by hot phenol-water, treated with RNase, then disaggregated in deoxycholic acid, and purified by gel filtration on Sephadex G-75. By comparison the conventional hot phenol-water purification method using repeated ultracentrifugations yielded less LOS. The yield of LOS by gel filtration was 30 to 108% higher and the purity was better.

Variability of cell surface hydrophobicity among Pasteurella multocida somatic serotype and Actinobacillus lignieresii strains

Pasteurella multocida possesses a characteristically gram-negative ultrastructure, yet its inability to grow in the presence of hydrophobic compounds and the general penicillin susceptibility of genera making up the family Pasteurellaceae suggest a cell envelope having atypical permeability properties. The cell surface hydrophobicity properties of strains representing 15 of the 16 somatic serotypes of P. multocida and three strains of Actinobacillus lignieresii were assessed with hydrocarbon adherence and hydrophobic interaction chromatographic assays. These methods revealed surface hydrophobicity to vary dramatically among strains in both species. No direct correlation was observed with species, growth rate, or susceptibility to the antibiotics oxytetracycline (polar), polymyxin B (amphiphilic), or novobiocin (nonpolar) as measured with MIC determinations. All strains were susceptible to the antibiotics, although A. lignieresii was significantly less susceptible than P. multocida to novobiocin. These data suggest that cell surface hydrophobicity in P. multocida may be influenced by the type of lipopolysaccharide present but is not directly related to permeability of the antibiotics examined. The wide diversity of hydrophobic properties exhibited by strains of both P. multocida and A. lignieresii precludes the use of this parameter as a taxonomic acid.

A field evaluation of Nobi-Vac atrophic rhinitis vaccine

A field trial was carried out with Nobi-Vac AR vaccine in 11 swine breeding herds. One herd suffered from severe B. bronchiseptica (BB+) rhinitis in piglets, while no clinical Atrophic Rhinitis (AR) was observed. Ten herds were described as AR problem herds, because clinical AR was observed for at least 1 year in spite of the fact that medication of sows and piglets was carried out and adequate housing and management systems were available in most herds. BB+ was isolated in 9 of these 10 farms and the AR pathogenic P. multocida (PM+) in all these farms. The trial started when piglets were born of sows which had been vaccinated 3 times. All piglets between 7 and 10 weeks old were examined clinically for AR. Nasal swabs from 20 pigs on each farm were screened bacteriologically for BB+ and PM+ every other month. A severe reoccurrence of AR was found in 2 of the 10 AR problem farms. In these 2 herds the 'all in-all out' system was not applied in farrowing and weaning houses. In the 8 other AR problem herds the percentage of pigs with AR decreased significantly below the average level of 1% per year. The percentage of pigs infected with BB+ and PM+ also decreased significantly. PM+ was significantly related to the percentage of clinical AR piglets. Seasonal effects contributed to a minor extent to the percentage of AR piglets. After 2.5 years of this trial PM+ could not be isolated during the last 12 months in six of the remaining AR problems herds. The conclusion is that Nobi-Vac AR vaccination of the sow gave protection against clinical AR in piglets on those farms (80%) which provided adequate housing and management systems.

Pasteurellosis in laboratory rabbits: characterization of lipopolysaccharides of Pasteurella multocida by polyacrylamide gel electrophoresis, immunoblot techniques, and enzyme-linked immunosorbent assay

The lipopolysaccharides (LPSs) of five isolates of Pasteurella multocida from rabbits were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblots, and enzyme-linked immunosorbent assay. Silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of purified unaggregated LPSs resembled those of semirough strains of gram-negative enterobacteria and consisted of one or two bands that migrated within an interval just ahead or slightly behind the migration of the Ra chemotype of "Salmonella minnesota," which has a molecular size of 4.3 kilodaltons. Polyclonal rabbit antisera to P. multocida whole cells used in Western blots and enzyme-linked immunosorbent assays of unabsorbed and LPS-absorbed antisera revealed that the LPS of these isolates of P. multocida contained at least two types of antigens: a nonserospecific antigen and a serospecific antigen. The LPSs of four isolates each had a different serospecific antigen. The nonserospecific antigen was expressed in two isolates and was the only demonstrable LPS antigen in one other isolate.

Biochemical and immunological characterization of cell surface proteins of Pasteurella multocida strains causing atrophic rhinitis in swine

In a previous paper (B. Lugtenberg, R. van Boxtel, and M. de Jong, Infect. Immun., 46:48-54, 1984) we showed that among 34 isolates from swine the membrane protein and lipopolysaccharide (LPS) patterns, as analyzed by sodium dodecyl sulfate-gel electrophoresis, could be classified into three and six patterns, respectively. In all cases a certain LPS pattern was correlated with a certain protein pattern. Certain combinations of types of cell surface proteins and LPSs were correlated with pathogenicity, the latter property being judged by the guinea pig skin test. In the present paper the immunological and biochemical properties of cell surface constituents were analyzed. The reaction between electrophoretically separated cell surface constituents with guinea pig and sow antisera showed that LPS as well as several proteins were immunogenic. Among these is protein H, whose electrophoretic mobility is the main criterium for typing of cell envelope protein patterns. Protein H was the most heavily labeled component when whole cells were iodinated by the Iodo-Gen procedure showing its accessibility at the cell surface. These properties of protein H make it an attractive vaccine candidate. Further biochemical analyses revealed that protein H shares many properties with pore proteins of members of the family Enterobacteriaceae. One of these properties, association between pore proteins and peptidoglycan, was used as the basis for a simple procedure developed to partially purify protein H.