Reduced use of antimicrobials after vaccination of pigs against porcine proliferative enteropathy in a Danish SPF herd. (25/50)


Interstrain diversity of 2-keto-3-deoxyoctonate content in lipopolysaccharides of Desulfovibrio desulfuricans. (26/50)

Bacteria of Desulfovibrio desulfuricans species are Gram-negative, anaerobic rods selectively reducing sulphates and colonizing oxygen-free ecosystems. They are ubiquitous in the natural environment and have been also found to reside in the human digestive tract. They are suggested to be involved in the pathogenesis ofulcerative colitis and Crohn's disease. The D. desulfuricans wild strains were isolated from feces and bioptate of patients suffering from various digestive tract disorders. LPSs were isolated from the wild enteric strains and soil type strain La 2226 of D. desulfuricans and analyzed in terms of their 2-keto-3-deoxyoctulosonic acid (Kdo) component content. The obtained spectrophotometric data indicate that Kdo content is characteristic of each of the investigated strains and it ranges from 0.48% to 2.86% (w/w) of the total LPS mass. Statistically significant interstrain differences of Kdo quantity seem to suggest the differences in the O-antigen content. Comparative analysis of Kdo content in LPSs of D. desulfuricans strains in relation to that of the reference endotoxin from Salmonella spp. allows us to suggest that D. desulfuricans bacteria possess O-antigen polysaccharides composed of diverse number of carbohydrate units.  (+info)

A TaqMan quantitative polymerase chain reaction assay for the detection of Lawsonia intracellularis in fecal and tissue samples from pigs. (27/50)

In the present study, a TaqMan quantitative polymerase chain reaction (qPCR) assay for detecting the 16S ribosomal RNA gene of Lawsonia intracellularis in porcine native ileal mucosal scrapings, fecal samples, and formalin-fixed and paraffin-embedded (FFPE) ileal samples is described. Samples from 62 pigs were examined. The results of the qPCR were compared with results obtained with conventional detection methods (PCR, immunohistochemistry, in situ hybridization, and silver staining) from a previous study and correlated well. The qPCR assay proved to be very sensitive and specific. In particular, the sensitivity of TaqMan PCR was significantly higher than conventional PCR on FFPE tissues because of a much shorter amplicon. A higher number of copies per gram of sample material was detected in native mucosa and FFPE tissue compared with feces, especially in highly positive animals. The detection limit for the qPCR was at 4 copies per well in native mucosal scrapings and 18 copies per well in feces and FFPE tissue, respectively. Inhibition of the qPCR reaction was checked by simultaneous detection of a recombinant beta-actin plasmid using a second fluorescent probe. A decreased signal from this internal control plasmid revealed inhibition of the PCR reaction in 21% of native mucosal samples and 1.6% of fecal samples. With a 10-fold dilution of template, the inhibition could be overcome.  (+info)

Application of a pig ligated intestinal loop model for early Lawsonia intracellularis infection. (28/50)


A quantitative polymerase chain reaction assay for detection and quantification of Lawsonia intracellularis. (29/50)

Lawsonia intracellularis, a causative agent of porcine proliferative enteropathy, is an obligate intracellular bacterium that is difficult to culture, propagate, and quantify. The intestinal epithelial cell line (IEC-18, derived from rat small intestine crypt cells) has been used to isolate and propagate this pathogen. However, the lack of rapid and simple quantification methods has led to mixed results when using the rat cell line, complicating Lawsonia studies. To overcome these limitations, a SYBR green quantitative polymerase chain reaction (qPCR) assay targeting a unique hypothetical protein was developed for detecting and quantifying L. intracellularis in IEC-18 rat epithelial cells, porcine fecal samples collected from different farms, and experimentally infected pigs. The method was optimized to detect as few as 3 copies per qPCR reaction of the bacterium growing in IEC-18 cells, providing a new and necessary approach to assess the growth of L. intracellularis in these cell lines. Furthermore, the qPCR assay was successful in detecting L. intracellularis in fecal samples collected from pigs with and without a history of Lawsonia infections, as well as in experimentally infected pigs, which further confirmed the suitability of the qPCR assay for studying the epidemiology of this pathogen.  (+info)

Evidence of cell-mediated immune response and specific local mucosal immunoglobulin (Ig) A production against Lawsonia intracellularis in experimentally infected swine. (30/50)

The purpose of this study was to detect cell-mediated and local humoral immune responses to Lawsonia intracellularis in pigs inoculated with a pure culture of the pathogenic isolate or with an intestinal mucosa homogenate. Twenty-four 5-week-old pigs were inoculated with a pure culture of L. intracellularis (n = 10), an intestinal mucosa homogenate from proliferative enteropathy diseased pigs (n = 10), or a control solution (n = 4). All animals were bled 0, 7, 14, and 20 d post-inoculation (pi). Serum was tested for immunoglobulin (Ig) G against L. intracellularis and for the production of interferon (IFN)-gamma by peripheral blood mononuclear cells (PBMC) after inoculation with L. intracellularis total proteins. Delayed-type hypersensitivity (DTH) reactions were evaluated 24 and 48 h after intra-dermal injection of different concentrations of L. intracellularis antigen 20 d pi. All animals were euthanized on day 22, intestinal lavages of ileum and IgA titrations were done. Weak IFN-gamma production was detected in 1 pig from the pure culture group and 2 pigs from the mucosal homogenate group 14 d pi, and in 2 animals from both groups 20 d pi. All pigs, in both inoculated groups, were seropositive for IgG on day 20. Inoculated pigs from both groups showed very weak dose-dependent DTH reactions, which were more evident at 24 h than 48 h pi. Eight pigs from the pure culture group and 7 from the mucosa homogenate group had detectable IgA titers in the intestinal lavage 22 d pi. In conclusion, specific local intestinal humoral and weak cell-mediated immune responses can be detected in pigs experimentally infected with L. intracellularis.  (+info)

Diagnostic performance of different fecal Lawsonia intracellularis-specific polymerase chain reaction assays as diagnostic tests for proliferative enteropathy in pigs: a review. (31/50)

Traditionally, diagnosis of Lawsonia intracellularis-associated proliferative enteropathy (PE) has depended on necropsy and histology. Since the establishment of the etiologic role of L. intracellularis, a number of specific polymerase chain reaction (PCR) assays have been developed for the detection of DNA in feces. The present article is a systematic review of peer-reviewed publications on the application of L. intracellularis-specific fecal PCR as an antemortem diagnostic test for histologic lesions of PE in pigs. Based on this information, a range of diagnostic sensitivities (36-100%) and specificities (50-100%) of the published tests was calculated. Validity and confidence limits of the estimates varied considerably. The positive and negative predictive values of 6 different PCR assays were calculated for PE prevalence of 15%, 30%, 45%, 60%, 75%, and 90%, using a histologic case definition of PE and based on the reported test sensitivities and specificities. The simulated predictive values suggested that applying the fecal PCR assay as a diagnostic test is more likely to overestimate than underestimate the number of pigs having histologic lesions of PE under field conditions.  (+info)

Polymicrobial bloodstream infection with Eggerthella lenta and Desulfovibrio desulfuricans. (32/50)