Expression of phospholipase D, the major virulence factor of Corynebacterium pseudotuberculosis, is regulated by multiple environmental factors and plays a role in macrophage death.
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Corynebacterium pseudotuberculosis is the aetiological agent of caseous lymphadenitis, a disease affecting sheep and goats. Phospholipase D (Pld), a major virulence determinant of C. pseudotuberculosis, is believed to play a critical role in dissemination of bacteria from the site of infection to the lymph nodes. Although the pld gene has been studied for some time, it is only recently that it has been identified as being down-regulated following heat shock from 37 to 43 degrees C. To gain insights into the mechanisms of Pld action, this study investigated how it was regulated under varying environmental conditions. Studies measuring pld mRNA levels or utilizing a reporter construct containing the pld promoter upstream of a gfp gene were performed. These showed that pld was upregulated in a cell-density-dependent manner, was regulated by heat shock at all cell-culture densities, and was highly expressed in a tissue-culture macrophage-infection model. Finally, the expression of Pld by intracellular C. pseudotuberculosis was shown to play a small but significant role in the reduction of macrophage viability following infection. This study demonstrates that the regulation of C. pseudotuberculosis pld is complex. This regulatory complexity may play an important role in allowing the pathogen to successfully adapt to the changing host environment during infection, migration, establishment and disease progression. (+info)
A field trial to evaluate a whole cell vaccine for the prevention of caseous lymphadenitis in sheep and goat flocks.
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A field trial to evaluate a whole cell vaccine for the prevention of caseous lymphadenitis (CLA) in sheep and goats was performed in one goat herd and one sheep flock over a period of three years. In goats, there was a nonstatistically significant trend for fewer cases of CLA in the vaccinated animals compared to the controls. In sheep, from six months to 36 months postinitial vaccination, the proportion of vaccinated sheep that developed CLA was significantly less (p less than 0.05) than in the control sheep. The antibody titers to Corynebacterium pseudotuberculosis as detected by microagglutination assay were significantly different (p less than 0.0001) at all times except at the initial vaccination. Swellings occurred at the vaccination site at an incidence level of 29.6% in goats and 34.1% in sheep. The vaccine appeared to be efficacious in reducing the proportion of sheep that developed CLA when challenged naturally in a field situation. (+info)
Acute phase protein response in an experimental model of ovine caseous lymphadenitis.
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BACKGROUND: Caseous lymphadenitis (CLA) is a disease of small ruminants caused by Corynebacterium pseudotuberculosis. The pathogenesis of CLA is a slow process, and produces a chronic rather than an acute disease state. Acute phase proteins (APP) such as haptoglobin (Hp) serum amyloid A (SAA) and alpha1 acid glycoprotein (AGP) are produced by the liver and released into the circulation in response to pro-inflammatory cytokines. The concentration of Hp in serum increases in experimental CLA but it is not known if SAA and AGP respond in parallel or have differing response profiles. RESULTS: The concentration in serum of Hp, SAA and AGP in 6 sheep challenged with 2 x 105 cells of C. pseudotuberculosis showed significant increases (P < 0.05) compared to 3 unchallenged control sheep. By day 7 post infection. (p.i.) the Hp and SAA concentrations reached mean (+/- SEM) values of 1.65 +/- 0.21 g/L and 18.1 +/- 5.2 mg/L respectively. Thereafter, their concentrations fell with no significant difference to those of the control sheep by day 18 p.i.. In contrast, the serum AGP concentration in infected sheep continued to rise to a peak of 0.38 +/- 0.05 g/L on day 13 p.i., after which a slow decline occurred, although the mean concentration remained significantly higher (P < 0.05) than the control group up to 29 days p.i.. Specific IgG to phospholidase D of C. pseudotuberculosis became detectable at 11 days p.i. and continued to rise throughout the experiment. CONCLUSION: The serum concentrations of Hp, SAA and AGP were raised in sheep in an experimental model of CLA. An extended response was found for AGP which occurred at a point when the infection was likely to have been transforming from an acute to a chronic phase. The results suggest that AGP could have a role as a marker for chronic conditions in sheep. (+info)
Lymphocyte subpopulations in pyogranulomas of caseous lymphadenitis.
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Pyogranulomas of ovine caseous lymphadenitis (CLA) are encapsulated lesions resulting from infections with Corynebacterium pseudotuberculosis, a bacterial pathogen able to grow within macrophages. Immunohistology of CLA lesions showed a band of lymphocytes lining the inside of the collagen capsule in intimate contact with necrotic tissue, the intracapsular lymphocytes being organized into three layers. The innermost layer, immediately adjacent to the central necrotic tissue consisted of a narrow band of MHC class II staining macrophages. Cells staining for CD4, CD8 and gamma delta T cell markers were unevenly distributed throughout the lymphoid layer, tending to be more numerous immediately external to the macrophage layer. The intracapsular lymphoid tissue contained a high proportion of CD8+ lymphocytes (CD4:CD8, 1.5:1) and of gamma delta lymphocytes (CD4:CD8:gamma delta, 1:0.7:0.8). External to the T cell-rich zone and adjacent to the surrounding collagen capsule was a dense band of cells, a proportion of which stained atypically for CD45R and were tentatively identified as B cells. CD8+ and gamma delta+ T cells showed similar distributions and their relative abundance, compared with CD4+ T cells, was a distinguishing feature of the CLA lesion. Staining for factor VIII-related antigen clearly showed endothelial venules throughout the intracapsular lymphoid tissue. The presence of endothelial venules and the organized architecture of the lymphoid tissue teleologically argues that lymphocytes are continually recruited into chronic CLA lesions and play an important role in the ongoing disease process. (+info)
Properties of corynephage attachment site and molecular epidemiology of Corynebacterium ulcerans isolated from humans and animals in Japan.
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Sporadic reports of Corynebacterium ulcerans infection in humans and animals have become increasingly common throughout the world. Between 2001 and 2006, five human cases, in addition to isolation of the bacterium from the carcasses of Orcinus orca and Panthera leo, were reported in Japan. While an isolate from P. leo generated only phospholipase D (PLD), the other isolates produced both PLD and diphtheria-like toxin (DLT). Pulsed-field gel electrophoresis analysis showed that isolates from P. leo and humans were genetically homologous. Southern blotting found that a human isolate was lysogenized by two corynephages coding DLT. Sequence analysis of the region of the DLT gene revealed that the integration in C. ulcerans occurred in the same manner as that in C. diphtheriae. (+info)
A description of genes of Corynebacterium pseudotuberculosis useful in diagnostics and vaccine applications.
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Corynebacterium pseudotuberculosis, a Gram-positive intracellular pathogen, is the etiological agent of caseous lymphadenitis or CLA. This bacterium infects goats and sheep and causes great economic losses worldwide annually, mainly for goat producers. Despite its importance, CLA is still poorly characterized. However, with advances in the genomic field, many C. pseudotuberculosis genes have already been characterized, mainly those related to virulence such as phospholipase D. Here, we examined the use of the several available genes of C. pseudotuberculosis and reviewed their applications in vaccine construction, more efficient diagnostics for CLA, and control of this disease, among other applications. (+info)
Evaluation of three methods for DNA fingerprinting of Corynebacterium pseudotuberculosis strains isolated from goats in Poland.
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Phenotypic approaches based on metabolic and biological characteristics of Corynebacterium pseudotuberculosis have been limited due to insufficient discrimination between closely related isolates. In this paper we present performance and convenience of three molecular typing methods: BOX-PCR, random amplification of polymorphic DNA (RAPD) and amplification of DNA fragments surrounding rare restriction site (ADSRRS-fingerprinting) in genome analysis of these bacteria. Among examined 61 strains there were distinguished four, eight and 10 different genotypes by BOX-PCR, RAPD and ADSRRS-fingerprinting, respectively. The value of discrimination index was the lowest for BOX-PCR (D = 0.265), much bigger for RAPD (D = 0.539) and the highest for ADSRRS-fingerprinting (D = 0.604). The good discriminatory ability and reproducibility of RAPD and ADSRRS-fingerprinting indicates that those techniques may be particularly applied for epidemiological studies of C. pseudotuberculosis isolates. We found that ADSRRS-fingerprinting is a rapid method offering good discrimination power, excellent reproducibility and may be applied for epidemiological studies of intraspecific genetic relatedness of C. pseudotuberculosis strains. (+info)
A survey of caseous lymphadenitis in small ruminant farms from two districts in Perak, Malaysia -- Kinta and Hilir Perak.
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A survey of Caseous Lymphadenitis (CLA), a bacterial infection in sheep and goats was conducted on small ruminant farms in two districts in Perak, namely Kinta and Hilir Perak. The objective of this survey is to determine the status of CLA infection in small ruminants. A total of 8 farms were screened, involving a total of 579 animals. Agar Gel Precipitation Test (AGPT) and Enzyme Linked Immuno Absorbent Assay (ELISA) were conducted on serum samples obtained from the animals. Results show that 8.5% of the animals had a positive reaction for AGPT test. It was found that 36 samples (17%) were found positive using both AGPT and ELISA methods, 9 samples (4%) were found positive only using AGPT method, 14 samples (6%)were found positive only using ELISA and 157 samples (73%) were found negative using both methods. Since there is no available data on the prevalence of the disease in the country, further epidemiological studies as well as reliable diagnostic detection methods need to be assessed for aiding in control and eradication programmes for this disease. (+info)