Variations in the virulence, for pregnant guinea pigs, of campylobacters isolated from man

Coid, C. R.; O'sullivan, A. M.; Doré, C. J.

doi:10.1099/00222615-23-2-187

Cited by 12 publications

(7 citation statements)

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“…is based on a limited number of early studies indicating that a relatively low proportion of different strains contained plasmids and one study in which plasmid content was not associated with disease in a guinea pig model (55). However, the relevance of this model, which measures abortion of pregnant guinea pigs following intraperitoneal injection (15,50,55), to diarrheal disease is arguable. The experimental observation that strain 81-176 contains plasmids, coupled with its relatively high levels of both internalization into intestinal epithelial cells in vitro (28,38) and virulence in ferrets (19,67) and human volunteers (8), led us to reevaluate the role of plasmids in the pathogenesis of this well-characterized strain of C. jejuni.…”

Section: Discussionmentioning

confidence: 99%

Involvement of a Plasmid in Virulence of Campylobacter jejuni 81-176

et al. 2000

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Campylobacter jejuni strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. Although one of the plasmids, termed pTet, carries a tetO gene, conjugative transfer of tetracycline resistance to another strain of C. jejuni could not be demonstrated. Partial sequence analysis of the second plasmid, pVir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to Helicobacter pylori proteins, including one encoded by the cag pathogenicity island. All four of these plasmid-encoded proteins show some level of homology to components of type IV secretion systems. Mutation of one of these plasmid genes, comB3, reduced both adherence to and invasion of INT407 cells to approximately one-third that seen with wild-type strain 81-176. Mutation of comB3 also reduced the natural transformation frequency. A mutation in a second plasmid gene, a virB11 homolog, resulted in a 6-fold reduction in adherence and an 11-fold reduction in invasion compared to the wild type. The isogenic virB11 mutant of strain 81-176 also demonstrated significantly reduced virulence in the ferret diarrheal disease model. The virB11 homolog was detected on plasmids in 6 out of 58 fresh clinical isolates of C. jejuni, suggesting that plasmids are involved in the virulence of a subset of C. jejuni pathogens.Although Campylobacter jejuni is one of the major causes of bacterial diarrhea worldwide (51, 59), the details of its molecular pathogenesis are not well understood. The clinical symptoms of campylobacter infection can range from a mild, watery diarrhea to a dysentery-like illness with fecal blood and leukocytes (2). Although there are reports of numerous cytotoxins, only the cytolethal distending toxin, which arrests eukaryotic cells at the G 2 phase of the cell cycle (64), has been characterized in detail. There are numerous reports that C. jejuni strains can invade intestinal epithelial cells in vitro (20,21,24,29,30,38), although levels of invasion by different strains vary considerably (20,28,38,52). Strain 81-176, originally isolated from a diarrheal outbreak associated with raw-milk consumption (31), is one of the best-characterized strains of C. jejuni. This strain has been shown to cause an inflammatory diarrhea in two human feeding studies (8; D. Tribble, unpublished data) and to cause disease in experimental models using primates (40) and ferrets (19,67). Further, C. jejuni strain 81-176 invades INT407 cells at levels higher than those of most other C. jejuni strains (28, 38).Plasmids have been found in between 19 and 53% of C. jejuni strains (5, 9-11, 41, 53-58), and many of these have been reported to be R plasmids that are transmissible among Campylobacter spp. but not to Escherichia coli (53)(54)(55)(56)(57)(58)60). Despite the importance of plasmids to virulence in numerous other pathogens, it is generally believed that plasmids play no role in Campylobacter pathogenicity. This paradigm is based on the rather low level at which plasmids ...

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Section: Discussionmentioning

confidence: 99%

Involvement of a Plasmid in Virulence of Campylobacter jejuni 81-176

et al. 2000

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“…For example, human clinical C. jejuni isolates display low virulence and no bacteremia in guinea pigs, whereas C. fetus tends to be more aggressive and better able to induce bacteremia in these animals [98]. Infection experiments with ferrets, after feeding or by gavage challenge, revealed that 38 out of 40 animals became colonized by C. jejuni, and that the subsequent diarrhoea lasted 2-4 days, with at least 20% of the animals developing bacteremia 2-5 days after inoculation [99].…”

Section: Campylobacter Bacteremia In Animalsmentioning

confidence: 99%

Campylobacterbacteremia: A rare and under-reported event?

Louwen¹,

Baarlen²,

Vliet³

et al. 2012

European Journal of Microbiology and Immunology

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“…as well as vaccine efficacy, providing a more cost effective model compared to the cattle natural host (Bryner et al, 1988;Bryner et al, 1979;Coid et al, 1987;Corbeil, 1980;Taylor and Bryner, 1984). The guinea pig model was found to be adequate when evaluating different vaccine doses, strains and adjuvants and indicated that an oil-based adjuvant strongly improved immunisation efficacy (BonDurant, 2005;Bryner et al, 1988).…”

Section: Vaccination and Experimental Infectionmentioning

confidence: 99%

Molecular diagnostic protocols for bovine genital campylobacteriosis using comparative genomics and virulence studies

Indjein¹

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Bovine genital campylobacteriosis is difficult to identify due to problems with the isolation of its causative agent Campylobacter fetus subspecies venerealis. To optimise isolation methods, three selective culture and three transport and enrichment media (TEMs) were evaluated using a pure C. fetus subsp. venerealis culture, with and without simulated field contamination by Pseudomonas aeruginosa. For optimal C. fetus subsp. venerealis isolation and growth, TEMs should be returned from the field within 48h of collection and plated within 4h onto Campylobacter selective agar plates incubated for 48-72h at 37°C under microaerophilic conditions. Longer transport or TEM incubation resulted in overgrowth of P. aeruginosa limiting C. fetus subsp. venerealis recovery.In order to establish an isolate collection, the parA real-time PCR assay was used to screen bull preputial secretions prior to culturing positive samples. A more sensitive real-time PCR assay was designed from the ISCfe1 insertion element and used to assess additional preputial samples, compared to the parA real-time assay. A proportion of real-time negative samples was also cultured. Fourteen cultures were obtained from either ISCfe1 (8/43; 18.6%) or parA (6/51; 11.8%) negative samples. ISCfe1 and parA sequences were obtained from isolates not confirmed by conventional methods suggesting that both parA and ISCfe1 may be found in organisms other than C. fetus subsp. venerealis. Molecular testing of cultures (n=84) confirmed the presence of these sequences in isolates identified as other Campylobacter spp. or Arcobacter-like organisms, while they were not always detected in all biochemically confirmed C. fetus subsp. venerealis isolates. The lack of specificity of all methods highlights the need for more reliable C. fetus subsp. venerealis-specific gene targets.The draft genomes of two C. fetus subsp. venerealis biovars aligned to C. fetus subsp. fetus genome provided 26 unique C. fetus subsp. venerealis regions. In order to identify new diagnostic targets, 13 putative conventional and one real-time PCR assays designed from contigs common to both C. fetus subsp. venerealis biovars were developed to screen the Campylobacter-like culture collection (n=84). Isolates biochemically identified as organisms other than C. fetus subsp.venerealis were positive on the new real-time and six conventional PCR assays, indicating that they were not suitable subspecies-specific markers. Seven assays detected isolates phenotyped as C. fetus subsp. venerealis except for two aerotolerant isolates recognized as C. fetus subsp. venerealis by iii other published methods. These seven gene targets could be further investigated for real-time PCR assay development as in silico BLAST analysis confirmed their conservation in the genomes of five of our C. fetus subsp. venerealis isolates. However, further bioinformatics analysis revealed that they were found in several C. fetus subsp. fetus strains, underlining that a pan-genomics study including multiple C. fetus genomes is ne...

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Variations in the virulence, for pregnant guinea pigs, of campylobacters isolated from man

Cited by 12 publications

References 4 publications

Involvement of a Plasmid in Virulence of Campylobacter jejuni 81-176

Involvement of a Plasmid in Virulence of Campylobacter jejuni 81-176

Campylobacterbacteremia: A rare and under-reported event?

Molecular diagnostic protocols for bovine genital campylobacteriosis using comparative genomics and virulence studies

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