Complete Circular Genome Sequences of Brachyspira hyodysenteriae Isolates of the Four Different Sequence Types Causing Swine Dysentery in Switzerland.
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SUBMITTER: Garcia-Martin AB
PROVIDER: S-EPMC8483663 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Swine dysentery (SD) is a mucohaemorrhagic colitis of grower/finisher pigs classically resulting from infection by the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. This study aimed to determine whether B. hyodysenteriae isolates from pigs in three healthy German multiplier herds supplying gilts to other farms differed from isolates from nine German production herds with SD. Isolates were subjected to whole genomic sequencing, and in silico multilocus sequence typing showed that those from the three multiplier herds were of previously undescribed sequence types (ST132, ST133 and ST134), with all isolates from the same herd having the same ST. All isolates were examined for the presence of 332 genes encoding predicted virulence or virulence lifestyle associated factors, and these were well conserved. Isolates from one multiplier herd were atypical in being weakly haemolytic: they had 10 amino acid substitutions in the haemolysin III protein and five in the haemolysin activation protein compared to reference strain WA1, and had a disruption in the promoter site of the hlyA gene. These changes likely contribute to the weakly haemolytic phenotype and putative lack of virulence. These same isolates also had nine base pair insertions in the iron metabolism genes bitB and bitC and lacked five of six plasmid genes that previously have been associated with colonisation. Other overall differences between isolates from the different herds were in genes from three of five outer membrane proteins, which were not found in all the isolates, and in members of a block of six plasmid genes. Isolates from three herds with SD had all six plasmid genes, while isolates lacking some of these genes were found in the three healthy herds-but also in isolates from six herds with SD. Other differences in genes of unknown function or in gene expression may contribute to variation in virulence; alternatively, superior husbandry and better general health may have made pigs in the two multiplier herds colonised by "typical" strongly haemolytic isolates less susceptible to disease expression.
| S-EPMC4973917 | biostudies-literature
Project description:The spirochete Brachyspira hyodysenteriae is the causative agent of swine dysentery, a severe colonic infection of pigs that has a considerable economic impact in many swine-producing countries. In spite of its importance, knowledge about the global epidemiology and population structure of B. hyodysenteriae is limited. Progress in this area has been hampered by the lack of a low-cost, portable, and discriminatory method for strain typing. The aim of the current study was to develop and test a multiple-locus variable-number tandem-repeat analysis (MLVA) method that could be used in basic veterinary diagnostic microbiology laboratories equipped with PCR technology or in more advanced laboratories with access to capillary electrophoresis. Based on eight loci, and when performed on isolates from different farms in different countries, as well as type and reference strains, the MLVA technique developed was highly discriminatory (Hunter and Gaston discriminatory index, 0.938 [95% confidence interval, 0.9175 to 0.9584]) while retaining a high phylogenetic value. Using the technique, the species was shown to be diverse (44 MLVA types from 172 isolates and strains), although isolates were stable in herds over time. The population structure appeared to be clonal. The finding of B. hyodysenteriae MLVA type 3 in piggeries in three European countries, as well as other, related, strains in different countries, suggests that spreading of the pathogen via carrier pigs is likely. MLVA overcame drawbacks associated with previous typing techniques for B. hyodysenteriae and was a powerful method for epidemiologic and population structure studies on this important pathogenic spirochete.
| S-EPMC2916602 | biostudies-literature
Project description:Swine dysentery caused by Brachyspira hyodysenteriae, results in substantial economic losses in swine producing countries worldwide. Although a number of different vaccine approaches have been explored with regard to this disease, they show limitations and none of them have reached the market. We here determine the vaccine potential of a weakly haemolytic B. hyodysenteriae strain. The virulence of this strain was assessed in experimental infection trials and its protection against swine dysentery was quantified in a vaccination-challenge experiment using a seeder infection model. Systemic IgG production and local IgA production were monitored in serum and faeces respectively. Across all trials, pigs that were colonized by virulent, strongly haemolytic B. hyodysenteriae strains consistently developed swine dysentery, in contrast to none of the pigs colonized by the weakly haemolytic B. hyodysenteriae vaccine strain. In the seeder vaccination trial nearly all immunised animals developed swine dysentery on subsequent challenge with a virulent strain, but the speed of spread of swine dysentery and faecal score were significantly reduced in animals immunised with the weakly haemolytic strain compared to sham-immunised animals. The IgA response of immunised animals upon challenge with a virulent B. hyodysenteriae strain significantly correlated to a later onset of disease. The correlation between local IgA production and protection induced by a weakly haemolytic B. hyodysenteriae strain provides leads for future vaccine development against swine dysentery.
| S-EPMC5629781 | biostudies-literature
Project description:Brachyspira hyodysenteriae is an etiological agent of swine dysentery (SD). Diet fermentability plays a role in development of SD, but the mechanism(s) of action are largely unknown. Thus, this study aimed to determine whether replacing lowly fermentable fiber with highly fermentable fiber would mitigate a 42 d B. hyodysenteriae challenge. Thirty-nine barrows were allocated to dietary treatment groups: (1) 20% corn distillers dried grain with solubles (DDGS), 0% beet pulp (BP) or resistant starch (RS; lowly fermentable fiber (LFF)); (2) 10% DDGS, 5% BP, 5% RS (medium fermentable fiber (MFF)); and (3) 0% DDGS, 10% BP, 10% RS (highly fermentable fiber (HFF)). On day post inoculation 0, pigs were inoculated with B. hyodysenteriae. Overall, 85% LFF pigs developed clinical SD, 46% of MFF pigs developed SD, and 15% of HFF pigs developed SD (p < 0.05). Overall average daily gain (ADG) differed among all treatments (p < 0.001), with LFF pigs having the lowest ADG. For HFF pigs, ADG was 37% greater than LFF pigs (p < 0.001) and 19% greater than MFF pigs (p = 0.037). The LFF diet had greater relative abundance of Shuttleworthia and Ruminococcus torques. Further, microbiota of pigs that developed SD had enriched Prevotellaceae. Collectively, replacing DDGS with highly fermentable fiber reduced clinical SD, improved performance, and modulated fecal microbiota during B. hyodysenteriae challenge.
| S-EPMC7915590 | biostudies-literature
Project description:Brachyspira hyodysenteriae is the aetiological agent of swine dysentery, a globally distributed disease that causes profound economic loss, impedes the free trade and movement of animals, and has significant impact on pig health. Infection is generally treated with antibiotics of which pleuromutilins, such as tiamulin, are widely used for this purpose, but reports of resistance worldwide threaten continued effective control. In Brachyspira hyodysenteriae pleuromutilin resistance has been associated with mutations in chromosomal genes encoding ribosome-associated functions, however the dynamics of resistance acquisition are poorly understood, compromising stewardship efforts to preserve pleuromutilin effectiveness. In this study we undertook whole genome sequencing (WGS) and phenotypic susceptibility testing of 34 UK field isolates and 3 control strains to investigate pleuromutilin resistance in Brachyspira hyodysenteriae. Genome-wide association studies identified a new pleuromutilin resistance gene, tva(A) (tiamulin valnemulin antibiotic resistance), encoding a predicted ABC-F transporter. In vitro culture of isolates in the presence of inhibitory or sub-inhibitory concentrations of tiamulin showed that tva(A) confers reduced pleuromutilin susceptibility that does not lead to clinical resistance but facilitates the development of higher-level resistance via mutations in genes encoding ribosome-associated functions. Genome sequencing of antibiotic-exposed isolates identified both new and previously described mutations in chromosomal genes associated with reduced pleuromutilin susceptibility, including the 23S rRNA gene and rplC, which encodes the L3 ribosomal protein. Interesting three antibiotic-exposed isolates harboured mutations in fusA, encoding Elongation Factor G, a gene not previously associated with pleuromutilin resistance. A longitudinal molecular epidemiological examination of two episodes of swine dysentery at the same farm indicated that tva(A) contributed to development of tiamulin resistance in vivo in a manner consistent with that seen experimentally in vitro. The in vitro studies further showed that tva(A) broadened the mutant selection window and raised the mutant prevention concentration above reported in vivo antibiotic concentrations obtained when administered at certain doses. We show how the identification and characterisation of tva(A), a new marker for pleuromutilin resistance, provides evidence to inform treatment regimes and reduce the development of resistance to this class of highly important antimicrobial agents.
| S-EPMC6018095 | biostudies-literature
Project description:The anaerobic intestinal spirochaete Brachyspira hyodysenteriae colonises the large intestine of pigs and causes swine dysentery (SD), a severe mucohaemorrhagic colitis. SD occurs worldwide, and control is hampered by a lack of vaccines and increasing antimicrobial resistance. B. hyodysenteriae strains typically produce strong beta-haemolysis on blood agar, and the haemolytic activity is thought to contribute to the pathogenesis of SD. Recently, weakly haemolytic variants of B. hyodysenteriae have been identified in Europe and Australia, and weakly haemolytic strain D28 from Belgium failed to cause disease when used experimentally to infect pigs. Moreover, pigs colonised with D28 and then challenged with virulent strongly haemolytic strain B204 showed a delay of 2-4 days in developing SD compared to pigs not exposed to D28. The current study aimed to determine whether Australian weakly haemolytic B. hyodysenteriae strain MU1, which is genetically distinct from D28, could cause disease and whether exposure to it protected pigs from subsequent challenge with strongly haemolytic virulent strains. Three experimental infection studies were undertaken in which no diseases occurred in 34 pigs inoculated with MU1, although mild superficial lesions were found in the colon in 2 pigs in one experiment. In two experiments, significantly fewer pigs exposed to MU1 and then challenged with strongly haemolytic virulent strains of B. hyodysenteriae developed SD compared to control pigs not previously exposed to MU1 (p?=?0.009 and p?=?0.0006). These data indicate that MU1 lacks virulence and has potential to be used to help protect pigs from SD.
| S-EPMC6585146 | biostudies-literature
Project description:Brachyspira (Serpulina) hyodysenteriae, the etiologic agent of swine dysentery, uses the enzyme NADH oxidase to consume oxygen. To investigate possible roles for NADH oxidase in the growth and virulence of this anaerobic spirochete, mutant strains deficient in oxidase activity were isolated and characterized. The cloned NADH oxidase gene (nox; GenBank accession no. U19610) on plasmid pER218 was inactivated by replacing 321 bp of coding sequence with either a gene for chloramphenicol resistance (cat) or a gene for kanamycin resistance (kan). The resulting plasmids, respectively, pCmDeltaNOX and pKmDeltaNOX, were used to transform wild-type B. hyodysenteriae B204 cells and generate the antibiotic-resistant strains Nox-Cm and Nox-Km. PCR and Southern hybridization analyses indicated that the chromosomal wild-type nox genes in these strains had been replaced, through allelic exchange, by the inactivated nox gene containing cat or kan. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblot analysis revealed that both nox mutant cell lysates were missing the 48-kDa Nox protein. Soluble NADH oxidase activity levels in cell lysates of Nox-Cm and Nox-Km were reduced 92 to 96% compared to the activity level in parent strain B204. In an aerotolerance test, cells of both nox mutants were at least 100-fold more sensitive to oxygen exposure than were cells of the wild-type parent strain B204. In swine experimental infections, both nox mutants were less virulent than strain B204 in that fewer animals were colonized by the mutant cells and infected animals displayed mild, transient signs of disease, with no deaths. These results provide evidence that NADH oxidase serves to protect B. hyodysenteriae cells against oxygen toxicity and that the enzyme, in that role, contributes to the pathogenic ability of the spirochete.
| S-EPMC91677 | biostudies-literature
Project description:BackgroundThe development of a mouse model as an in vivo pathogenicity screening tool for Brachyspira spp. has advanced the study of these economically important pathogens in recent years. However, none of the murine models published to date have been used to characterize the clinical signs of disease in mice, instead focusing on pathology following oral inoculation with various Brachyspira spp. The experiments described herein explore modifications of published models to characterize faecal consistency, faecal shedding and pathology in mice challenged with "Brachyspira hampsonii" clade II (Bhamp).Methods and resultsIn Experiment 1, 24 CF-1 mice were randomly allocated to one of three inoculation groups: sham (Ctrl), Bhamp, or B. hyodysenteriae (Bhyo; positive control). Half of each group was fed normal mouse chow (RMH) while the other received a low-zinc diet (TD85420). In Experiment 2, eight CF-1 mice and nine C3H/HeN mice were divided into Ctrl or Bhamp inoculation groups, and all fed TD85420. In Experiment 1, mice fed TD85420 demonstrated more severe mucoid faeces (P = 0.001; Kruskal Wallis) and faecal shedding for a significantly greater number of days (P = 0.005; Kruskal Wallis). Mean faecal scores of Bhamp inoculated mice trended higher than Ctrl (P = 0.06; Wilcoxon rank-sum) as did those of Bhyo mice (P = 0.0; Wilcoxon rank-sum). In Experiment 2, mean faecal scores of inoculated CF-1 mice were significantly greater than in C3H mice (P = 0.049; Kruskal Wallis) but no group differences in faecal shedding were observed. In both experiments, mice clustered based on the severity of colonic and caecal histopathology but high lesion scores were not always concurrent with high fecal scores.ConclusionIn our laboratory, CF-1 mice and the lower-zinc TD85420 diet provide a superior murine challenge model of "Brachyspira hampsonii" clade II.
| S-EPMC5568335 | biostudies-literature
Project description:Swine dysentery (SD) is an economically important diarrheal disease in pigs caused by different strongly hemolytic Brachyspira (B.) species, such as B. hyodysenteriae, B. suanatina and B. hampsonii. Possible associations of epidemiologic data, such as multilocus sequence types (STs) to virulence gene profiles and antimicrobial susceptibility are rather scarce, particularly for B. hyodysenteriae isolates from Germany. In this study, B. hyodysenteriae (n = 116) isolated from diarrheic pigs between 1990 and 2016 in Germany were investigated for their STs, susceptibility to the major drugs used for treatment of SD (tiamulin and valnemulin) and genes that were previously linked with virulence and encode for hemolysins (tlyA, tlyB, tlyC, hlyA, BHWA1_RS02885, BHWA1_RS09085, BHWA1_RS04705, and BHWA1_RS02195), outer membrane proteins (OMPs) (bhlp16, bhlp17.6, bhlp29.7, bhmp39f, and bhmp39h) as well as iron acquisition factors (ftnA and bitC). Multilocus sequence typing (MLST) revealed that 79.4% of the isolates belonged to only three STs, namely ST52 (41.4%), ST8 (12.1%), and ST112 (25.9%) which have been observed in other European countries before. Another 24 isolates belonged to twelve new STs (ST113-118, ST120-123, ST131, and ST193). The temporal distribution of STs revealed the presence of new STs as well as the regular presence of ST52 over three decades (1990s-2000s). The proportion of strains that showed resistance to both tiamulin und valnemulin (39.1%) varied considerably among the most frequent STs ranging from 0% (0/14 isolates resistant) in ST8 isolates to 46.7% (14/30), 52.1% (25/48), and 85.7% (6/7) in isolates belonging to ST112, ST52, and ST114, respectively. All hemolysin genes as well as the iron-related gene ftnA and the OMP gene bhlp29.7 were regularly present in the isolates, while the OMP genes bhlp17.6 and bhmp39h could not be detected. Sequence analysis of hemolysin genes of selected isolates revealed co-evolution of tlyB, BHWA1_RS02885, BHWA1_RS09085, and BHWA1_RS02195 with the core genome and suggested independent evolution of tlyA, tlyC, and hlyA. Our data indicate that in Germany, swine dysentery might be caused by a limited number of B. hyodysenteriae clonal groups. Major STs (ST8, ST52, and ST112) are shared with other countries in Europe suggesting a possible role of the European intra-Community trade of pigs in the dissemination of certain clones. The identification of several novel STs, some of which are single or double locus variants of ST52, may on the other hand hint towards an ongoing diversification of the pathogen in the studied area. The linkage of pleuromutilin susceptibility and sequence type of an isolate might reflect a clonal expansion of the underlying resistance mechanism, namely mutations in the ribosomal RNA genes. A linkage between single virulence-associated genes (VAGs) or even VAG patterns and the phylogenetic background of the isolates could not be established, since almost all VAGs were regularly present in the isolates.
| S-EPMC5764319 | biostudies-literature
Project description:BACKGROUND: Mucohaemorrhagic diarrhea caused by Brachyspira hyodysenteriae, swine dysentery, is a severe production limiting disease of swine. Recently, pigs in western Canada with clinical signs indistinguishable from swine dysentery were observed. Despite the presence of spirochetes on fecal smears, recognized Brachyspira spp. including B. hyodysenteriae could not be identified. A phylogenetically distinct Brachyspira, called "B. hampsonii" strain 30446, however was isolated. The purpose of this study was to experimentally reproduce mucohaemorrhagic colitis and characterize strain 30446 shedding following inoculation. METHODS AND FINDINGS: Eighteen 13-week-old pigs were randomly assigned to inoculation (n?=?12) or control (n?=?6) groups in each of two trials. In trial 1, pigs were inoculated with a tissue homogenate collected from clinically affected field cases. In trial 2, pigs were inoculated with a pure broth culture of strain 30446. In both trials, mucohaemorrhagic diarrhea was significantly more common in inoculated pigs than controls, all of which remained healthy. In animals with mucohaemorrhagic diarrhea, significantly more spirochetes were observed on Gram stained fecal smears, and higher numbers of strain 30446 genome equivalents were detected by quantitative PCR (qPCR). Strain 30446 was cultured from colon and/or feces of all affected but no control animals at necropsy. CONCLUSIONS: "Brachyspira hampsonii" strain 30446 causes mucohaemorrhagic diarrhea in pigs following a 4-9 day incubation period. Fecal shedding was detectable by day 4 post inoculation, and rarely preceded the onset of mucoid or haemorrhagic diarrhea by more than 2 days. Culture and 30446-specific qPCR are reliable methods of detection of this organism in feces and tissues of diarrheic pigs. The emergence of a novel Brachyspira spp., such as "B. hampsonii", creates diagnostic challenges including higher risk of false negative diagnostic tests. We therefore recommend diagnostic laboratories routinely use Brachyspira culture, nox-based and species-specific PCR, and DNA sequencing to diagnose Brachyspira-associated colitis in pigs.
| S-EPMC3584117 | biostudies-literature