2F3 Monoclonal Antibody Recognizes the O26 O-Antigen Moiety of the Lipopolysaccharide of Enterohemorrhagic Escherichia coli Strain 4276

in Clinical and Diagnostic Laboratory Immunology (2004), 11(3), 532-537

Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) organisms are groups of pathogenic strains whose infections are characterized by a typical lesion of enterocyte attachment and ... [more ▼]

Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) organisms are groups of pathogenic strains whose infections are characterized by a typical lesion of enterocyte attachment and effacement. They are involved in enteric diseases both in humans and in animals, and EHEC strains can be responsible for hemolytic uremic syndrome in humans. Previously, it was shown that the 2F3 monoclonal antibody (MAb) is specific for the O26 EHEC and EPEC strains (P. Kerr, H. Ball, B. China, J. Mainil, D. Finlay, D. Pollock, I. Wilson, and D. Mackie, Clin. Diagn. Lab. Immunol. 6:610–614, 1999). As these groups of bacteria play an important role in pathology, the aim of this paper was to characterize the antigen recognized by the 2F3 MAb and its genetic determinant. A genomic locus containing the entire O-antigen gene cluster and half of the colanic acid gene cluster from an O26 EHEC strain was shown to be sufficient for the production of the antigen recognized by the 2F3 MAb in an E. coli DH5 strain. By transposon mutagenesis performed on the recombinant plasmid, all 2F3 enzyme-linked immunosorbent assay-negative mutants had their transposons inserted into the O-antigen gene cluster. The O-antigen gene cluster was also cloned from an O26 EHEC strain into the E. coli DH5 strain, which then produced a positive result with the 2F3 MAb. Further analysis of the type of lipopolysaccharides (smooth or rough) produced by the clones and mutants and of the O antigen of the 2F3-positive clones confirmed that the epitope recognized by the 2F3 MAb is located on the O antigen in the O26 EHEC and EPEC strains and that its genetic determinant is located inside the O-antigen gene cluster. [less ▲]

Pathophysiological changes occurring during Escherichia coli endotoxin and Pasteurella multocida challenge in piglets: relationship with cough and temperature and predicitive value for intensity of lesions.

in Veterinary Research (2004), 35(3), 309-324

The aims of this study were (1) to correlate cough and body temperature (BT) with the severity of bronchopneumonia in pigs, (2) to determine whether these clinical signs can be used to early diagnose ... [more ▼]

The aims of this study were (1) to correlate cough and body temperature (BT) with the severity of bronchopneumonia in pigs, (2) to determine whether these clinical signs can be used to early diagnose bronchopneumonia and (3) to assess the predictive values of cough and BT regarding lung lesions. Bronchopneumonia was induced by administering E. coli endotoxin (LPS) combined with Pasteurella multocida type A (PmA) in the trachea of 13 piglets. Saline-instilled negative controls (n = 8), PmA inoculated (n = 6) and LPS instilled (n = 5) groups were also constituted. Cough and BT were recorded daily while the bronchopneumonia severity was assessed using bronchoalveolar lavage fluid (BALF) cytology, cytokines and measurement of lung lesion volume. Changes in expiratory breathing pattern were also measured (Penh). The combination of LPS and PmA induced a subacute bronchopneumonia characterised by macrophage, neutrophil, and lymphocyte infiltration, changes in Penh and an increase in the mRNA level of IFN-gamma while IL8, IL-18 and TNF-alpha mRNA levels remained unchanged. The daily body weight gain of infected animals was significantly reduced. Cough and BT changes were proportional to the intensity of the lung inflammatory process, functional respiratory changes and to the extent of macroscopic lesions. When comparing the individual values of cough and BT to thresholds defined for both parameters, an early diagnosis of pneumonia was possible. Considering the pooled data of each group, it was possible to define thresholds allowing an early segregation between the groups of diseased and healthy piglets. The daily values of cough and BT were predictive for the volume of lung lesions recorded at the end of the trial. In conclusion, cough and BT appear as potential indicators for the intensity and the evolution of the respiratory disease. They also seem to be good predictors for the magnitude of lung lesions and weight gain recorded at the study endpoint. [less ▲]

Conservation of the uvrC gene sequence in Mycoplasma bovis and its use in routine PCR diagnosis

in Veterinary Journal (2004), 168

Mycoplasma bovis is a major cause of pneumonia and arthritis in calves, and of mastitis and genital infections in adult cows. It is responsible for high economic loss in feedlot cattle although it is ... [more ▼]

Mycoplasma bovis is a major cause of pneumonia and arthritis in calves, and of mastitis and genital infections in adult cows. It is responsible for high economic loss in feedlot cattle although it is often underestimated and is widely spread within the bovine population in enzootically infected areas. [less ▲]

Virulence factors and specific properties of invasive Escherichia coli : IV) Necrotoxigenic strains

in Annales de Médecine Vétérinaire (2004), 148(3), 121-132

Escherichia coli bacterial species is subdivided into several pathogen strains in man and animals, on the basis of their specific properties and factors which are responsible for their virulence. The ... [more ▼]

Escherichia coli bacterial species is subdivided into several pathogen strains in man and animals, on the basis of their specific properties and factors which are responsible for their virulence. The pathogenic strains are classically subdivided into strains with intestinal tropism (enterotoxigenic, enteropathogenic, enterohaemmorrhagic, verotoxigenic and enteroinvasive) and with extraintestinal tropism (uropathogenic and invasive). Invasive strains cause septicaemia and/or bacteraemia with localisations in different internal organs (systemic infections). If specific virulence properties and factors of strains with intestinal tropism are quite well known and described, those of strains with extraintestinal tropism are much less characterised, especially in animals. The purpose of this series of review articles is to present the current knowledge on specific properties and factors of extraintestinal strains. The first three manuscripts reviewed the characteristics of adhesins and colonisation factors, transmucosal transfer, survival in blood and internal organs, and toxicity. After the presentation of the animal and human invasive E. coli, this fourth manuscript reviews the current knowledge on the necrotoxigenic strains and finishes with a discussion on the meaning of the bacterial virulence in general. [less ▲]

Les mycoplasmes respiratoires bovins: prévalence et propriétés de cyto-adhésion

Report (2004)

Putative roles of the CNF2 and CDTIII toxins in experimental infections with necrotoxigenic Escherichia coli type 2 (NTEC2) strains in calves

in Microbes & Infection (2003), 5(13), 1189-1193

Newborn colostrum-restricted calves were orally inoculated with an Escherichia coli strain, identified originally as non-pathogenic, and into which the plasmid pVir was conjugally transferred. This ... [more ▼]

Newborn colostrum-restricted calves were orally inoculated with an Escherichia coli strain, identified originally as non-pathogenic, and into which the plasmid pVir was conjugally transferred. This resulted in diarrhea, intestinal lesions and extra-intestinal invasion, suggesting that factors affecting these pathogenic properties are located on pVir. In order to analyze the respective roles of the toxins CNF2 and CDTIII in the pathogenesis, colostrum-restricted calves were inoculated with isogenic mutants in the cnf2 and the cdt-III genes. The loss of cnf2 is associated with a reduction in the pathogenicity, since diarrhea does not occur in calves challenged, in spite of successful colonization of the intestine. Nevertheless, the mutant strain remains able to invade the bloodstream and to localize in the internal organs. Conversely, the calves inoculated with mutant in the cdt-III gene evolved in the same way as wild-type strain-inoculated calves with regard to clinical signs and macroscopic or microscopic lesions. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved. [less ▲]

Antibiotic susceptibilities of recent isolates of Mycoplasma bovis in Belgium

in Veterinary Record : Journal of the British Veterinary Association (2003), 153(14), 428-431

The susceptibilities of 40 recent Belgian field isolates of Mycoplasma bovis to 10 antimicrobial agents were assessed. Tiamulin was the most active antimicrobial agent against M bovis, with an initial ... [more ▼]

The susceptibilities of 40 recent Belgian field isolates of Mycoplasma bovis to 10 antimicrobial agents were assessed. Tiamulin was the most active antimicrobial agent against M bovis, with an initial inhibitory concentration (IIC50) of 0.06 microg/ml, but it is not licensed for the treatment of cattle. All three fluoroquinolones tested (danofloxacin, enrofloxacin and marbofloxacin) were effective against strains of M bovis, and had a minimum mycoplasmacidal concentration (MMC50) less than or equal to 1 microg/ml. Gentamicin was poorly effective, having an IIC50 of 8 microg/ml. Many strains of M bovis were resistant to tylosin, spectinomycin, lincomycin, tetracycline and oxytetracycline. [less ▲]

Increased nuclear Factor kappa B activity in milk cells of mastitis-affected cows

in Journal of Dairy Science (2003), 86(4), 1259-1267

Bacterial mastitis is accompanied by a drastic increase in milk somatic cell count (SCC), with neutrophils being the predominant cell type found in the infected quarters. Accumulation and activation of ... [more ▼]

Bacterial mastitis is accompanied by a drastic increase in milk somatic cell count (SCC), with neutrophils being the predominant cell type found in the infected quarters. Accumulation and activation of neutrophils at the site of infection require local expression of many inflammatory genes encoding adhesion molecules, chemokines and cytokines. Most of the inflammatory genes contain binding sites for the nuclear factor kappaB (NF-kappaB) within their promoter and therefore partly depend on NF-kappaB for their expression. We thus hypothesized that an increase in NF-kappaB activity in the mammary gland could contribute to development of the neutrophilic inflammation that characterizes mastitis. In an attempt to verify this hypothesis, we first assessed milk cells from healthy and acute and chronic mastitis-affected cows for NF-kappaB activity using electrophoretic mobility shift assays. We next studied the relationships between the intensity of NF-kappaB activity in these cells and the degree of udder inflammation. Active NF-kappaB complexes were undetectable in milk cells from healthy cows, whereas high levels of NF-kappaB activity were always found in cells from cows with acute mastitis. In milk cells obtained from chronic mastitis-affected cows, NF-kappaB activity varied from low to high. Finally, the level of NF-kappaB activity measured in milk cells from chronic mastitis-affected cows was not correlated to SCC or to the proportion of neutrophils present in milk samples, but was highly correlated with the expression level of interleukin-8 and granulocyte/macrophage colony-stimulating factor, two NF-kappaB-dependent cytokines crucially involved in initiation and perpetuation of neutrophilic inflammation. These results suggest that NF-kappaB might play a role in mastitis pathogenesis. [less ▲]

Adherence to various cell lines of Mycoplasma bovis strains differing in pathogenic and cultural features

in Veterinary Microbiology (2003), 91

Mycoplasma bovis is known to be responsible for pneumonia and arthritis in calves, as well as mastitis in dairy cows. Despite clear evidence of its pathogenic potential, little is known about mechanisms ... [more ▼]

Mycoplasma bovis is known to be responsible for pneumonia and arthritis in calves, as well as mastitis in dairy cows. Despite clear evidence of its pathogenic potential, little is known about mechanisms of cytadherence and the molecular factors involved. The purpose of this work was to compare adherence rates of M. bovis field strains to different host cell lines and study the effects of cloning and sub-culturing M. bovis strains on their adherence properties. Eighteen metabolically labeled M. bovis strains isolated from different pathological backgrounds were examined in adherence trials using four different host cell lines, i.e. embryonic bovine lung (EBL), embryonic bovine trachea (EBTr), Madin Darby bovine kidney (MDBK) and rabbit kidney (RK) cells. Although large interstrain variations in adherence rates (3.4-19.1%) were measured they could not be correlated to the pathological background (pneumonia, arthritis or mastitis). Adherence rates to the fibroblast cell line (EBTr) were significantly lower than those to the three epithelial cell lines (EBL, MDBK and RK). The only non-pathogenic strain (221/89) exhibited lower adherence rates than three isolates from clinical mastitis. Interestingly, adherence rates were significantly reduced after in vitro passaging. In contrast, no effect of single cloning of strains on adherence was observed. There was no general correlation between expression of variable surface proteins (Vsps) as monitored by immunoblotting and adherence rates, although alterations in Vsp expression profiles were seen as a consequence of passaging. As there is probably a large number of adhesins, variable and non-variable, on the surface of M. bovis cells the issue is very complex, and the most active components have yet to be identified. [less ▲]

Mycoplasma bovis dans le complexe respiratoire bovin et propriétés de cyto-adhésion in vitro

in Annales de Médecine Vétérinaire (2003), 147(4, AUG-SEP), 267-272

Mycoplasmas frequently infect cattle, causing especially respiratory diseases. Mycoplasma bovis is the most important pathogenic species in countries free of bovine contagious pleuropneumonia. This ... [more ▼]

Mycoplasmas frequently infect cattle, causing especially respiratory diseases. Mycoplasma bovis is the most important pathogenic species in countries free of bovine contagious pleuropneumonia. This species was frequently isolated in Belgium from cattle with respiratory disease. Furthermore, associations were often observed with pasteurellas and bovine respiratory syncytial virus. Of these M. bovis isolates, many were resistant to several antimicrobial agents which are used in cattle practice, except to fluoroquinolones. Inasmuch the high frequency of M. bovis isolation and antibiotic resistances, it is very important to understand the pathogenicity of this bacteria in order to optimize prophylactic tools. Therefore, the study of the cytadherence of M. bovis is essential since it represents the first step of the bacterial infection. According to our experimental results, PG45 is not representative of field isolates because of its low adherence rates to various cell lines. This could be explained by the high number of subcultures of this pathogenic strain underwent since its first isolation, which sharply contrasts with other isolates. M. bovis adheres specifically to bovine bronchial epithelial cells in primary culture. Proteins such as variable surface proteins C and F are involved in this step as observed by decreased adherence rates after trypsinization of mycoplasma cells or addition of monoclonal antibodies. [less ▲]