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Immunological alterations during the clinical and recovery phases of experimental swine dysentery.

The aim of this study was to examine changes in the systemic immune response during the incubation period and following the onset of clinical swine dysentery, including the recovery period. Ten healthy conventional pigs were inoculated with Brachyspira hyodysenteriae. Blood was sampled at pre-inoculation, at days 4 and 14 post-inoculation, during the first 4 days with clinical signs of dysentery and at days 1, 3, 7, 11 and 15 of the recovery period. Eight pigs developed haemorrhagic diarrhoea. Flow-cytometric analyses of lymphocyte subpopulations showed that all animals, including the two that remained healthy, had an increase in CD8alpha+ CD4- cells and gammadelta T cells at days 4 and 14 post-inoculation. In addition, an increase in CD4+ CD8alpha+ cells and CD8alpha+ CD8beta+ cells was observed at days 4 and 14 post-inoculation in animals that developed dysentery. During clinical signs of dysentery, the acute-phase protein serum amyloid A was increased. There was a two- to threefold increase in both neutrophils and monocytes during signs of dysentery and at the beginning of the recovery period. The numbers of CD8alpha+ CD8beta- CD4-, CD45RA- lymphocytes also increased during the dysentery period. Circulating CD21+ cells and CD21+ CD45RA- cells decreased at the end of the incubation period, during signs of dysentery and at the beginning of the recovery period. The dysentery-affected animals developed antibodies to B. hyodysenteriae-specific antigens (approximately 16 kDa and approximately 30 kDa) from the first day of recovery, and gammadelta T cells showed an increase during the recovery period. In comparison with pre-inoculation, increased numbers of monocytes, neutrophils, CD8alpha+ CD8beta- CD4- lymphocytes and CD45RA- lymphocytes were observed during clinical dysentery. Increased numbers of neutrophils, gammadelta T cells and specific antibodies were seen during the recovery period.

Animals↗

Analysis of genes of tetrahydrofolate-dependent metabolism from cultivated spirochaetes and the gut community of the termite Zootermopsis angusticollis.

The hindguts of wood-feeding termites are the sites of intense, CO2-reductive acetogenesis. This activity profoundly influences host nutrition and methane emissions. Homoacetogens previously isolated from diverse termites comprised novel taxa belonging to two distinct bacterial phyla, Firmicutes and Spirochates. Little else is known about either the diversity or abundance of homoacetogenic species present in any given termite or the genetic details underlying CO2-reductive acetogenesis by Spirochaetes. A key enzyme of CO2-reductive acetogenesis is formyltetrahydrofolate synthetase (FTHFS). A previously designed primer set was used to amplify FTHFS genes from three isolated termite-gut spirochaetes. Sequencing DNA flanking the FTHFS gene of Treponema strain ZAS-2 revealed genes encoding two acetogenesis-related enzymes, methenyltetrahydrofolate cyclohydrolase and methylenetetrahydrofolate dehydrogenase. Although termite-gut spirochaetes are only distantly related to clostridia at the ribosomal level, their tetrahydrofolate-dependent enzymes appear to be closely related. In contrast, homologous proteins identified in the non-homoacetogenic oral spirochaete Treponema denticola were only distantly related to those from clostridia and the termite-gut treponemes. Having demonstrated their utility with spirochaete pure cultures, the FTHFS primers were used to construct a 91-clone library from the termite-gut community DNA. From this, 19 DNA and eight amino acid FTHFS types were identified. Over 75 % of the retrieved clones formed a novel, coherent cluster with the FTHFS homologues obtained from the termite-gut treponemes. Thus, FTHFS gene diversity in the gut of the termite Zootermopsis angusticollis appears to be dominated by spirochaetes. The homoacetogenic capacity of termite-gut spirochaetes may have been acquired via lateral gene transfer from clostridia.

Animals↗

Unification of the genera Serpulina and Brachyspira, and proposals of Brachyspira hyodysenteriae Comb. Nov., Brachyspira innocens Comb. Nov. and Brachyspira pilosicoli Comb. Nov.

The phylogenetic positions of Serpulina hyodysenteriae, Serpulina innocens, Serpulina pilosicoli and Brachyspira aalborgi were studied. Complete 16S ribosomal DNA sequences of these three species and B. aalborgi revealed that their 16S rDNA sequences were related more than 96.0%. The mol% guanine plus cytosine (G+C) of B. aalborgi DNA was 27.1, and was similar to those of the 3 members of the genus Serpulina. The homologous rates using 31P-labeled B. aalborgi chromosome DNA in DNA-DNA reassociation tests were 22.0% to S. hyodysenteriae, 19.1% to S. innocens and 17.2% to S. pilosicoli. Therefore, we propose to transfer the three species of the genus Serpulina to the genus Brachyspira. Descriptions of Brachyspira hyodysenteriae comb. nov., Brachyspira innocens comb. nov. and Brachyspira pilosicoli comb. nov., and an emended description of B. aalborgi are given. Phenotypic characteristics of the 4 members of the genus Brachyspira were also studied. They fermented fructose, galactose, glucose, lactose, maltose, mannose, raffinose and trehalose; however, B. aalborgi did not ferment raffinose. All of them hydrolyzed esculin but did not produce indole except for B. hyodysenteriae. The protein profile of B. aalborgi was different from those of the four strains of B. hyodysenteriae, B. innocens and B. pilosicoli, but the heavy bands with molecular sizes of 49.4 and 52.3 kDa of B. aalborgi were quite similar to those of B. innocens in the points of quantity and molecular size. In immunoblotting tests, B. aalborgi reacted well with anti-B. innocens and B. pilosicoli sera, but reacted weakly with anti-B. hyodysenteriae serum. Only one heavy band and several faint bands were revealed by the reaction between B. aalborgi and anti-B. hyodysenteriae serum, and the heavy band was common among these strains.

Bacterial Typing Techniques↗

Polymerase chain reaction for identification of human and porcine spirochaetes recovered from cases of intestinal spirochaetosis.

A polymerase chain reaction (PCR) amplification of 16S rDNA was developed to identify spirochaetes recovered from cases of intestinal spirochaetosis in humans and pigs; these bacteria belong to a distinct genetic group of spirochaetes, with the proposed name 'Anguillina coli'. The PCR incorporated a universal eubacterial 16S rDNA sequencing primer (1492r), and a 21-base forward primer designed to include a nucleotide sequence specific for 'A. coli'. The PCR was used to correctly identify DNA extracted from 43 isolates of 'A. coli' from humans and pigs, whilst no product was produced from Escherichia coli, or from other intestinal spirochaetes, including 38 isolates of Serpulina spp., and one each of Treponema succinifaciens and Brachyspira aalborgi. The amplification provided a rapid and simple means of identifying DNA from isolates of 'A. coli', and could be used on boiled whole 'A. coli' cells, with a detection limit equivalent to 2.5 x 10(2) cells. The reaction was used to detect and identify these spirochaetes from selective agar plates inoculated with stool specimens from infected pigs.

Animals↗

A monoclonal antibody reacting with the cell envelope of spirochaetes isolated from cases of intestinal spirochaetosis in pigs and humans.

A monoclonal antibody (mAb) designed BJL/AC1 was prepared against the cell envelope of an intestinal spirochaete (strain 3295) that was isolated from a pig with intestinal spirochaetosis. The mAb reacted with a band of approximately 29 kDa in cell envelope preparations from 13 porcine and 11 human spirochaetes isolated from cases of intestinal spirochaetosis, but did not react with preparations made from a range of other intestinal spirochaetes. Immunogold labelling demonstrated that the reactive epitope was located on the cell envelope of the strains causing intestinal spirochaetosis. The mAb was used in an indirect immunofluorescence test to detect spirochaetes in the faeces of pigs with experimentally induced intestinal spirochaetosis. The mAb should prove to be a useful reagent for detection and identification of spirochaetes that are specifically associated with intestinal spirochaetosis.

Animals↗

Spirochaetes and other bacterial species associated with bovine digital dermatitis.

The 16S rRNA genes from spirochaetes associated with digital dermatitis of British cattle were amplified by polymerase chain reaction from digital dermatitis lesion biopsies using one universal and one treponeme-specific primer. Two treponemal sequences were identified both of which shared a high degree of homology with the oral pathogen Treponema denticola (98%). Two further 16S rRNA gene sequences were obtained and shared similarity to Bacteroides levii (99%) and Mycoplasma hyopharyngis (98%). Polymerase chain reaction with T. denticola-specific primers amplified a potential virulence gene from digital dermatitis lesions which shared a high degree of homology to the 46-kDa haemolysin gene of T. denticola. The significance of the presence of organisms in digital dermatitis lesions of the bovine foot which are closely related to oral pathogens is discussed.

Amino Acid Sequence↗

Phylogenetic relationships of symbiotic spirochetes in the gut of diverse termites.

Phylogenetic relationships of symbiotic spirochetes in the gut of diverse termites were analyzed without cultivation of these microorganisms. A portion of the 16S rDNA (ca. 850 bp) was amplified directly from DNA of the mixed population in the gut by PCR and cloned. A total of 30 spirochetal phylotypes affiliated with the treponemes were identified from four termite species and they were compared with those already reported from other termites. They represented separate lines of descent from any known species of Treponema, and they were divided into two discrete clusters; one was related to Spirochaeta stenostrepta and S. caldaria, and the other was grouped together with members of the Treponema bryantii subgroup. Although some sequences from evolutionarily related termites showed close similarity, most of the sequences of spirochetes were dissimilar among different termite species, and spirochetal sequences from a single termite species occurred in several distinct phylogenetic positions. These findings suggest that termites constitute a rich reservoir of novel spirochetal diversity and that evolution of the symbiosis is not simple.

Animals↗

Nitrogen fixation by symbiotic and free-living spirochetes.

Spirochetes from termite hindguts and freshwater sediments possessed homologs of a nitrogenase gene (nifH) and exhibited nitrogenase activity, a previously unrecognized metabolic capability in spirochetes. Fixation of 15-dinitrogen was demonstrated with termite gut Treponema ZAS-9 and free-living Spirochaeta aurantia. Homologs of nifH were also present in human oral and bovine ruminal treponemes. Results implicate spirochetes in the nitrogen nutrition of termites, whose food is typically low in nitrogen, and in global nitrogen cycling. These results also proffer spirochetes as a likely origin of certain nifHs observed in termite guts and other environments that were not previously attributable to known microbes.

Acetylene↗

Acetogenesis from H2 plus CO2 by spirochetes from termite guts.

Pure cultures of termite gut spirochetes were obtained and were shown to catalyze the synthesis of acetate from H2 plus CO2. The 16S ribosomal DNA sequences of two strains were 98 percent similar and were affiliated with those of the genus Treponema. However, neither was closely related to any known treponeme. These findings imply an important role for spirochetes in termite nutrition, help to reconcile the dominance of acetogenesis over methanogenesis as an H2 sink in termite hindguts, suggest that the motility of termite gut protozoa by means of attached spirochetes may be based on interspecies H2 transfer, and underscore the importance of termites as a rich reservoir of novel microbial diversity.

Acetates↗

Small pectinolytic spirochetes from the rumen.

Two strains of small spirochetes utilizing pectin as sole source of energy for growth were isolated from the rumen of cattle and partially characterized. The pectinolytic enzyme produced by one of the organisms was classified as a poly-1,4-alpha-D-galacturonide lyase (EC 4.2.2.2). A pectinesterase (EC 3.1.1.11) was also produced.

Animals↗

Phylogeny of not-yet-cultured spirochetes from termite guts.

Comparisons of 16S rDNA sequences were used to determine the phylogeny of not-yet-cultured spirochetes from hindguts of the African higher termite, Nasutitermes lujae (Wasmann). The 16S rRNA genes were amplified directly from spirochete-rich hindguts by using universal primers, and the amplified products were cloned into Escherichia coli. Clones were screened with a spirochete-specific DNA probe. Analysis of 1,410 base positions of the 16S rDNA insert from one spirochete clone, designated NL1, supported its assignment to the genus Treponema, with average interspecies similarities of ca. 85%. The sequence of NL1 was most closely related (ca. 87 to 88% similarity) to sequences of Spirochaeta stenostrepta and Spirochaeta caldaria and to a previously published sequence (ca. 87% similarity) of spirochetal clone MDS1 from the Australian lower termite, Mastotermes darwiniensis (Froggatt). On the basis of 16S rRNA sequence comparisons and individual base signatures, clones NL1 and MDS1 clearly represent two novel species of Treponema, although specific epithets have not yet been proposed. The gross morphology of NL1 was determined from in situ hybridization experiments with an NL1-specific, fluorescently labeled oligonucleotide probe. Cells were approximately 0.3 to 0.4 by 30 microns in size, with a wavelength and amplitude of about 10 microns and 0.8 to 1.6 micron, respectively. Moreover, electron microscopy of various undulate cells present in gut contents confirmed that they possessed ultrastructural features typical of spirochetes, i.e., a wavy protoplasmic cylinder, periplasmic flagella, and an outer sheath. The sequence data suggest that termite gut spirochetes may represent a separate line of descent from other treponemes and that they constitute a significant reservoir of previously unrecognized spirochetal biodiversity.

Animals↗

Phylogenetic diversity of the intestinal bacterial community in the termite Reticulitermes speratus.

The phylogenetic diversity of the intestinal microflora of a lower termite, Reticulitermes speratus, was examined by a strategy which does not rely on cultivation of the resident microorganisms. Small-subunit rRNA genes (16S rDNAs) were directly amplified from the mixed-population DNA of the termite gut by the PCR and were clonally isolated. Analysis of partial 16S rDNA sequences showed the existence of well-characterized genera as well as the presence of bacterial species for which no 16S rDNA sequence data are available. Of 55 clones sequenced, 45 were phylogenetically affiliated with four of the major groups of the domain Bacteria: the Proteobacteria, the spirochete group, the Bacteroides group, and the low-G+C-content gram-positive bacteria. Within the Proteobacteria, the 16S rDNA clones showed a close relationship to those of cultivated species of enteric bacteria and sulfate-reducing bacteria, while the 16S rDNA clones in the remaining three groups showed only distant relationships to those of known organisms in these groups. Of the remaining 10 clones, among which 8 clones formed a cluster, there was only very low sequence similarity to known 16S rRNA sequences. None of these clones were affiliated with any of the major groups within the domain Bacteria. The 16S rDNA gene sequence data show that the majority of the intestinal microflora of R. speratus consists of new, uncultured species previously unknown to microbiologists.

Animals↗

Phylogenetic position and in situ identification of ectosymbiotic spirochetes on protists in the termite gut.

Phylogenetic relationships, diversity, and in situ identification of spirochetes in the gut of the termite Neotermes koshunensis were examined without cultivation, with an emphasis on ectosymbionts attached to flagellated protists. Spirochetes in the gut microbial community investigated so far are related to the genus Treponema and divided into two phylogenetic clusters. In situ hybridizations with a 16S rRNA-targeting consensus oligonucleotide probe for one cluster (known as termite Treponema cluster I) detected both the ectosymbiotic spirochetes on gut protists and the free-swimming spirochetes in the gut fluid of N. koshunensis. The probe for the other cluster (cluster II), which has been identified as ectosymbionts on gut protists of two other termite species, Reticulitermes speratus and Hodotermopsis sjoestedti, failed to detect any spirochete population. The absence of cluster II spirochetes in N. koshunensis was confirmed by intensive 16S ribosomal DNA (rDNA) clone analysis, in which remarkably diverse spirochetes of 45 phylotypes were identified, almost all belonging to cluster I. Ectosymbiotic spirochetes of the three gut protist species Devescovina sp., Stephanonympha sp., and Oxymonas sp. in N. koshunensis were identified by their 16S rDNA and by in situ hybridizations using specific probes. The probes specific for these ectosymbionts did not receive a signal from the free-swimming spirochetes. The ectosymbionts were dispersed in cluster I of the phylogeny, and they formed distinct phylogenetic lineages, suggesting multiple origins of the spirochete attachment. Each single protist cell harbored multiple spirochete species, and some of the spirochetes were common among protist species. The results indicate complex relationships of the ectosymbiotic spirochetes with the gut protists.

Animals↗

Variation in a major surface protein of Lyme disease spirochetes.

Two monoclonal antibodies (H6831 and H5TS) differed in their indirect immunofluorescence reactivity when tested against 14 strains of Lyme disease spirochetes. Strains were bound by both antibodies, by H6831 or H5TS alone, or by neither. Western blot and immunoprecipitation studies revealed that the determinants of both antibodies were associated with abundant proteins with apparent subunit molecular weights of ca. 34,000 (34K-range proteins). The following results indicated that the 34K-range proteins were exposed on the surface of the spirochetes. (i) Antibody H6831 agglutinated the spirochetes; (ii) immune electron microscopy showed that the H6831 determinant was associated with the outer membrane; (iii) radiolabeled H6831 bound to live organisms; and (iv) proteases effectively removed the 34K-range proteins from intact cells. With their demonstrated variability and exposure on the surface, the 34K-range proteins may contribute to the serotype specificity of Lyme disease spirochetes.

Agglutination Tests↗

Genetic relationship of lyme disease spirochetes to Borrelia, Treponema, and Leptospira spp.

Genetic studies were performed on the following spirochetes: three Lyme disease spirochetes isolated from Ixodes ticks and from human spinal fluid; three species of North American borreliae; four species of Treponema; and two species of Leptospira. The mol% G+C values for Lyme disease spirochetes were 27.3 to 30.5%, similar to values of 28.0 to 30.5% for Borrelia species but different from the values of Leptospira or Treponema species which ranged from 35.3 to 53%. Lyme disease spirochetes represent a new species of Borrelia, with DNA homologies of 31 to 59% with the three North American strains of Borrelia studied. These studies also showed that Lyme disease spirochetes from three sources constituted a single species, with DNA homologies ranging from 76 to 100%. A high degree of relatedness was also seen between the three North American borreliae, with homology varying from 77 to 95%, indicating that these spirochetes represent a single species. Lyme disease spirochetes and Borrelia species exhibited almost no homology with Leptospira and Treponema species (0 to 2%). Plasmids were detected in the three Lyme disease spirochetes and in the three North American borreliae.

Animals↗

DNA characterization of the spirochete that causes Lyme disease.

Lyme disease, a tick-borne disease long recognized in Europe but only recently recognized in the United States, was shown in 1982-1983 to be caused by a spirochete, the Lyme disease spirochete. Whether one or more species of the spirochete exists is unknown, as is its taxonomic status. To answer these questions, we determined (i) the DNA base (guanidine-plus-cytosine) content for five strains; (ii) the DNA relatedness of 10 strains from Europe or the United States (isolated from ticks, humans, and a mouse) by DNA hybridization (hydroxyapatite assay at 50 and 65 degrees C); and (iii) the DNA relatedness to other pathogenic spirochetes. The guanine-plus-cytosine content of the Lyme disease spirochete strains was 27.5 to 29.0 mol%, most similar to those of Borrelia hermsii (30.6 mol%) and Treponema hyodysenteriae (25.6 mol%) among the other spirochetes tested. DNA hybridization studies with 32P-labeled DNA from Lyme disease spirochete strain TLO-005, a human blood isolate, revealed divergence (unpaired bases) within related nucleotide sequences of only 0.0 to 1.0% for all nine Lyme disease spirochete strains tested for relatedness to TLO-005. Relatedness values of seven strains to TLO-005 were 58 to 98% (mean, 71%) in 50 degrees C reactions and 50 to 93% (mean, 69%) in 65 degrees C reactions. Two other strains, from which very low yields of DNA were obtained, showed less relatedness (36 to 50 degrees C, 38 to 47% at 65 degrees C). These were nonetheless considered to belong to the same species because of the low amount of divergence in the sequences related to TLO-005 and the absence of decreased relatedness in reactions done at 65 degrees Celsius compared with those done at 50 degrees Celsius. DNA from strain TLO-005 showed relatedness of 1% to DNAs of two leptospires and 16% relatedness to DNA from T. hyodysenteriae. B. hermsii DNA was 30 to 40% related to three Lyme disease spirochete strains in 50 degrees Celsius reactions. Divergence in these reactions was 16.5 to 18.5%, and relatedness in 65 degree Celsius reactions was 8 to 10%. On the bases of phenotypic similarity, guanine-plus-cytosine content, and DNA relatedness to B. hermsii, we conclude the Lyme disease spirochete is single previously undescribed species which belongs in the genus Borrelia.

Animals↗