An avirulent Brachyspira hyodysenteriae strain elicits intestinal IgA and slows down spread of swine dysentery

Mahu, Maxime; Boyen, Filip; Canessa, Stefano; Marchan, Jackeline Cecilia Zavala; Haesebrouck, Freddy; Martel, An; Pasmans, Frank

doi:10.1186/s13567-017-0465-y

Cited by 17 publications

(25 citation statements)

References 35 publications

(43 reference statements)

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“…Thus, novel strategies for an effective control of SD, probably involving hemolysin genes as targets, are urgently required. Several attempts to develop a vaccine against B. hyodysenteriae have failed [36][37][38] or are still under progress [39]. The hemolysins TlyA and TlyC may be promising candidates for the development of a subunit vaccine to control swine dysentery in pigs.…”

Section: Resultsmentioning

confidence: 99%

Differential expression of hemolysin genes in weakly and strongly hemolytic Brachyspira hyodysenteriae strains

et al. 2020

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Background: Swine dysentery (SD) is a diarrheal disease in fattening pigs that is caused by the strongly hemolytic species Brachyspira (B.) hyodysenteriae, B. hampsonii and B. suanatina. As weakly hemolytic Brachyspira spp. are considered less virulent or even non-pathogenic, the hemolysin is regarded as an important factor in the pathogenesis of SD. Four hemolysin genes (tlyA, tlyB, tlyC, and hlyA) and four putative hemolysin genes (hemolysin, hemolysin activation protein, hemolysin III, and hemolysin channel protein) have been reported, but their role in strong hemolysis is not entirely clear. Our study aimed to assess the transcriptional activity of eight (putative) hemolysin genes in a strongly hemolytic (B204) and a weakly hemolytic (G423) B. hyodysenteriae strain during nonhemolytic and hemolytic growth stages. Results: Strongly and weakly hemolytic B. hyodysenteriae strains caused hemolysis on blood agar at different growth stages, namely during log phase (B204) and stationary/death phase (G423). During the lag, early log, late log (stationary phase in G423) and death phase (time points 1-4) strains differed in their hemolysin gene transcription patterns. At time point 1, transcription of the putative hemolysin gene was higher in B204 than in G423. At time point 2, tlyA and tlyC were upregulated in B204 during hemolysis. TlyB and hlyA were upregulated in both strains at all time points, but higher transcription rates were observed in the weakly hemolytic strain G423. The transcription activity of the hemolysin channel protein gene was quite similar in both strains, whereas the hemolysin activation protein gene was upregulated in the non-hemolytic stage of B204 at time point 4. Sequence analysis revealed deletions, insertions and single nucleotide polymorphisms in the G423 hlyA promoter, although without altering the transcription activity of this gene. Conclusion: Our data indicate a combined activity of TlyA and TlyC as the most probable underlying mechanism of strong hemolysis in B. hyodysenteriae. Further studies should verify if the expression of tlyA is upregulated by the putative hemolysin gene. Depending on their immunogenic potential TlyA and TlyC may serve as possible vaccine candidates, especially since vaccines for an effective control of swine dysentery are currently not available.

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Section: Resultsmentioning

confidence: 99%

Differential expression of hemolysin genes in weakly and strongly hemolytic Brachyspira hyodysenteriae strains

et al. 2020

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“…Haemolysin(s) produced by B. hyodysenteriae appear to be an important virulence factor, and natural weakly haemolytic strains recently have been identified in pig herds where there is little or no disease [14–16]. One weakly haemolytic strain from Belgium (D28) has been shown to be avirulent in experimentally infected pigs [17], and consequently it was hypothesised that Australian strain MU1 also may be avirulent, even if it belonged to a different genetic subgroup to D28 (MU1 is ST151 and D28 is ST172). D28 is a member of a clade of weakly haemolytic B. hyodysenteriae isolates that to date has only been described in Europe [28].…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, in pigs colonised with D28 and then challenged with virulent strongly haemolytic B. hyodysenteriae strain B204, the development of SD was delayed by an average of 2–4 days compared to pigs not previously exposed to the D28. Nevertheless, 28 of the 30 pigs in both groups succumbed to SD within 30 days, so there was not significant protection against disease [17].…”

Section: Introductionmentioning

confidence: 99%

An atypical weakly haemolytic strain of Brachyspira hyodysenteriae is avirulent and can be used to protect pigs from developing swine dysentery

Phillips

Coiacetto

et al. 2019

Vet Res

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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. Electronic supplementary material The online version of this article (10.1186/s13567-019-0668-5) contains supplementary material, which is available to authorized users.

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“…No commercial vaccines are currently available. Different experimental inactivated [ 9 – 11 ] and attenuated [ 12 , 13 ] vaccines have been tested but so far protective immunity has been limited. Three farms in this study used an autogenous vaccine.…”

Section: Introductionmentioning

confidence: 99%

Implementation and evaluation of different eradication strategies for Brachyspira hyodysenteriae

et al. 2020

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Background Brachyspira infections are causing major losses to the pig industry and lead to high antimicrobial use. Treatment of Brachyspira (B.) hyodysenteriae infections may be problematic due to the high level of antimicrobial resistance. The present study implemented and evaluated farm-specific eradication programmes for B. hyodysenteriae in 10 different infected pig farms in Belgium. Results Ten pig farms clinically infected with B. hyodysenteriae volunteered to implement a farm-specific eradication programme. The programme depended on the farm and management characteristics, antimicrobial susceptibility of the B. hyodysenteriae strain and the motivation of the farmer. Two farms practiced total depopulation, six farms partial depopulation and two farms antimicrobial medication without depopulation. In addition, all farms implemented biosecurity measures, and faeces samples were tested for the presence of B. hyodysenteriae at 6, 9 and 12 months after the start of the program. Single Brachyspira isolates from before and after the programme were typed using multilocus sequence typing (MLST). Eradication was successful in four farms. Two of them (farrow-to-finish and finishing herd) had applied total depopulation and respected a vacancy period of at least 3 weeks. A third farm (gilt farm) practised partial depopulation, the rooms remained empty for 28 days and changed the source of breeding gilts. The fourth farm practised partial depopulation, the stables remained empty for 3 weeks, and used antimicrobial medication. The eradication programme was not successful in six farms. Two of the latter farms only used medication without partial depopulation. Four farms practiced partial depopulation, one of them combined it with antimicrobial medication. The cleaning and disinfection procedures, rodent control, stand-empty period and/or other biosecurity measures in the six farms were not always implemented properly. In two of three farms, isolates belonging to the same MLST type were found before and after eradication. Conclusions Total depopulation or partial depopulation combined with implementing strict biosecurity measures allowed eradication of B. hyodysenteriae from clinically infected pig farms. Programmes based on antimicrobials without depopulation or partial depopulation without strictly adhering to all suggested biosecurity measures were not successful. Stockmanship and motivation of the farmer to permanently maintain high biosecurity standards are essential for success.

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An avirulent Brachyspira hyodysenteriae strain elicits intestinal IgA and slows down spread of swine dysentery

Cited by 17 publications

References 35 publications

Differential expression of hemolysin genes in weakly and strongly hemolytic Brachyspira hyodysenteriae strains

Differential expression of hemolysin genes in weakly and strongly hemolytic Brachyspira hyodysenteriae strains

An atypical weakly haemolytic strain of Brachyspira hyodysenteriae is avirulent and can be used to protect pigs from developing swine dysentery

Implementation and evaluation of different eradication strategies for Brachyspira hyodysenteriae

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