Evidence for niche adaptation in the genome of the bovine pathogen Streptococcus uberis.

BACKGROUND: Streptococcus uberis, a Gram positive bacterial pathogen responsible for a significant proportion of bovine mastitis in commercial dairy herds, colonises multiple body sites of the cow including the gut, genital tract and mammary gland. Comparative analysis of the complete genome sequence of S. uberis strain 0140J was undertaken to help elucidate the biology of this effective bovine pathogen. RESULTS: The genome revealed 1,825 predicted coding sequences (CDSs) of which 62 were identified as pseudogenes or gene fragments. Comparisons with related pyogenic streptococci identified a conserved core (40%) of orthologous CDSs. Intriguingly, S. uberis 0140J displayed a lower number of mobile genetic elements when compared with other pyogenic streptococci, however bacteriophage-derived islands and a putative genomic island were identified. Comparative genomics analysis revealed most similarity to the genomes of Streptococcus agalactiae and Streptococcus equi subsp. zooepidemicus. In contrast, streptococcal orthologs were not identified for 11% of the CDSs, indicating either unique retention of ancestral sequence, or acquisition of sequence from alternative sources. Functions including transport, catabolism, regulation and CDSs encoding cell envelope proteins were over-represented in this unique gene set; a limited array of putative virulence CDSs were identified. CONCLUSION: S. uberis utilises nutritional flexibility derived from a diversity of metabolic options to successfully occupy a discrete ecological niche. The features observed in S. uberis are strongly suggestive of an opportunistic pathogen adapted to challenging and changing environmental parameters.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

The pathogenicity of Escherichia coli which cause diarrhoea in calves with particular reference to the characterisation, distribution and role of adhesins.

6 were partiallypurified from a K99 - variant of E. coli B41. One was identical to the anionic antigen, adhered to calf brush borders and did not have a regular fimbrial structure. The second was a polymer of two polypeptide subunits with molecular weights of 49,500 and 48,000; it was antigenically distinct from K99 and the anionic antigen, did not adhere to brush borders or isolated villi and had a fimbrial structure. An immunoperoxidase test indicated that the second haemagglutinin was produced in the ileum of a gnotobiotic calf infected with E, coli B41. Agglutination of sheep erythrocytes by the second haemagglutinin was inhibited by any of ten sugars. The receptor was present in glycolipid extracts of sheep erythrocytes. K99 was the only detectable adhesin on E. coli B117. This organism produced three polypeptides of similar molecular weight to the anionic antigen which did not adhere to brush borders or isolated villi. Results of an immunoradiometric assay suggested that the K99 of different strains was not identical. Calves fed colostrum which contained natural IgM antibodies that were opsonic were not protected against infection by K99 E. coli. However, the presence of a normal gut flora together with colostrum provided some protection. A blocking immunoradiometric assay which detected antibody to K99 in calves previously infected with K99 E. coli failed to detect antibody in sera from 248 calves collected between 1971 and 1975 on a progeny testing station. During the winters of 1981-1983 a survey of calves with diarrhoea in South England revealed that K99 E. coli caused approximately 4% of the outbreaks examined. An atypical E. coli isolated from calves with dysentery caused dysentery in experimentally infected gnotobiotic calves by colonising the mucosa of the colon and by production of petechial haemorrhages

The pathogenicity of Escherichia coli which cause diarrhoea in calves with particular reference to the characterisation, distribution and role of adhesins.

6 were partiallypurified from a K99 - variant of E. coli B41. One was identical to the anionic antigen, adhered to calf brush borders and did not have a regular fimbrial structure. The second was a polymer of two polypeptide subunits with molecular weights of 49,500 and 48,000; it was antigenically distinct from K99 and the anionic antigen, did not adhere to brush borders or isolated villi and had a fimbrial structure. An immunoperoxidase test indicated that the second haemagglutinin was produced in the ileum of a gnotobiotic calf infected with E, coli B41. Agglutination of sheep erythrocytes by the second haemagglutinin was inhibited by any of ten sugars. The receptor was present in glycolipid extracts of sheep erythrocytes. K99 was the only detectable adhesin on E. coli B117. This organism produced three polypeptides of similar molecular weight to the anionic antigen which did not adhere to brush borders or isolated villi. Results of an immunoradiometric assay suggested that the K99 of different strains was not identical. Calves fed colostrum which contained natural IgM antibodies that were opsonic were not protected against infection by K99 E. coli. However, the presence of a normal gut flora together with colostrum provided some protection. A blocking immunoradiometric assay which detected antibody to K99 in calves previously infected with K99 E. coli failed to detect antibody in sera from 248 calves collected between 1971 and 1975 on a progeny testing station. During the winters of 1981-1983 a survey of calves with diarrhoea in South England revealed that K99 E. coli caused approximately 4% of the outbreaks examined. An atypical E. coli isolated from calves with dysentery caused dysentery in experimentally infected gnotobiotic calves by colonising the mucosa of the colon and by production of petechial haemorrhages