Swine dysentery is causally associated with Brachyspira hampsonii and B. hyodysenteriae infection. Given the importance of transmission models in understanding re-emergent diseases and developing ...control strategies such as vaccines, the objective of this experiment was to evaluate two experimental natural transmission (seeder pig) models in grower pigs, each with 24 animals. Seeder pigs were intragastrically inoculated using broth cultures of either B. hampsonii strain 30446 (genomovar II) or B. hyodysenteriae strain G44. In trial 1, three seeder pigs were placed into two pens containing nine susceptible contact pigs creating a 1:3 seeder:contact ratio. This was sufficient to achieve natural B. hampsonii infection of 13/18 (72%) contact pigs, however, the incidence of mucoid or mucohemorrhagic diarrhea (MMHD) in contact pigs differed significantly between pens (4/9 versus 9/9; P = 0.03). In trial 2, eight seeder pigs inoculated intragastrically with B. hampsonii did not develop MMHD but when re-inoculated with B. hyodysenteriae 14 days later, all developed mucohemorrhagic diarrhea within 13 days of re-inoculation. Two seeder pigs were placed into each of 4 contact pens each containing 4 pigs. This 1:2 seeder:contact ratio resulted in natural infection of 14/16 (87%) contact pigs with incubation period ranging from 9-15 days. There were no significant differences among pens in incubation period, duration, clinical period or severity of diarrhea. These trials demonstrated that a 1:2 seeder:contact ratio with groups of six grower pigs per pen sustained natural transmission of B. hyodysenteriae G44 with greater consistency in the incidence of MMHD among pens compared to a B. hampsonii 30446 transmission model using 1:3 seeder:contact ratio in pens of 12. Understanding why B. hampsonii intragastric inoculation failed in one experiment warrants additional research.
Swine dysentery is causally associated with
Brachyspira hampsonii
and
B
.
hyodysenteriae
infection. Given the importance of transmission models in understanding re-emergent diseases and developing ...control strategies such as vaccines, the objective of this experiment was to evaluate two experimental natural transmission (seeder pig) models in grower pigs, each with 24 animals. Seeder pigs were intragastrically inoculated using broth cultures of either
B
.
hampsonii
strain 30446 (genomovar II) or
B
.
hyodysenteriae
strain G44. In trial 1, three seeder pigs were placed into two pens containing nine susceptible contact pigs creating a 1:3 seeder:contact ratio. This was sufficient to achieve natural
B
.
hampsonii
infection of 13/18 (72%) contact pigs, however, the incidence of mucoid or mucohemorrhagic diarrhea (MMHD) in contact pigs differed significantly between pens (4/9 versus 9/9;
P
= 0.03). In trial 2, eight seeder pigs inoculated intragastrically with
B
.
hampsonii
did not develop MMHD but when re-inoculated with
B
.
hyodysenteriae
14 days later, all developed mucohemorrhagic diarrhea within 13 days of re-inoculation. Two seeder pigs were placed into each of 4 contact pens each containing 4 pigs. This 1:2 seeder:contact ratio resulted in natural infection of 14/16 (87%) contact pigs with incubation period ranging from 9–15 days. There were no significant differences among pens in incubation period, duration, clinical period or severity of diarrhea. These trials demonstrated that a 1:2 seeder:contact ratio with groups of six grower pigs per pen sustained natural transmission of
B
.
hyodysenteriae
G44 with greater consistency in the incidence of MMHD among pens compared to a
B
.
hampsonii
30446 transmission model using 1:3 seeder:contact ratio in pens of 12. Understanding why
B
.
hampsonii
intragastric inoculation failed in one experiment warrants additional research.
Swine dysentery (SD) is a worldwide production-limiting disease of growing-finishing pigs in commercial farms. The importance of the large intestinal microbiota in the swine dysentery pathogenesis ...has been established, but not well characterized. The objective of this study was to characterize the fecal bacterial microbiota of pigs immediately prior to developing clinical signs of swine dysentery. A total of 60 fecal samples were collected from 15 pigs with SD. Sampling times included a time point prior to SD (d0, n=15), 2 days before mucohaemorrhagic diarrhea was observed (d-2SD, n=15), 1 day before mucohaemorrhagic diarrhea was observed (d-1SD, n=15), and the day when pigs developed mucohemorragic diarrhea (MHD, n=15). Sequencing of cpn60 amplicons was used to profile the microbiome, and analyses were performed on QIIME2. Increased Chao1 index in d-1SD and MHD samples when compared to the d0 was the only change observed in alpha diversity. No differences between sampling times on beta diversity (Bray-Curtis dissimilarity) were found. Although a small sample size was investigated, differential abundance analysis revealed that Alistipes dispar and Parabacteroides gordonii were increased in MHD fecal samples when compared to d-2SD and d-1SD. It is suggested that these taxa may play a role in the pathogenesis of SD, which is known to require the presence of Brachyspira spp. and an anaerobe for severe disease development.
Swine dysentery (SD) caused by pathogenic Brachyspira spp. is an economic challenge for the swine industry. In research settings, experimental reproduction of swine dysentery typically relies on ...intragastric inoculation which has shown variable success. This project aimed to improve the consistency of the experimental inoculation protocol used for swine dysentery in our laboratory. Over six experiments, we evaluated the influence of group housing in inoculated pigs using a frozen-thawed broth culture of strongly hemolytic B. hyodysenteriae strain D19 (Trial A), compared the relative virulence of B. hyodysenteriae strains D19 and G44 (Trial B), compared inoculum volumes (50 mL vs 100 mL) for G44 and B. hampsonii 30446 (Trial C), and performed three independent trials evaluating intragastric inoculation using different oral inoculation methods: oral feed balls (Trial D), and oral syringe bolus of 100 mL (Trial E) or 300 mL (Trial F). Intragastric inoculation with a fresh broth culture of B. hyodysenteriae strain G44 resulted in a shorter incubation period and a higher proportionate duration of mucohemorrhagic diarrhea (MMHD) compared to D19. Intragastric inoculation with either 50 or 100 mL of B. hampsonii 30446 or B. hyodysenteriae (G44) were statistically equivalent. Oral inoculation with 100 mL or 300 mL also yielded similar results to intragastric inoculation but was more expensive due to the additional work and supplies associated with syringe training. Our future research will use intragastric inoculation with 100 mL of a fresh broth culture containing B. hyodysenteriae strain G44 as it yields a high incidence of mucohaemorrhagic diarrhea with a reasonable cost.
Brachyspira hampsonii causes dysentery-like disease in infected pigs. Serial passage of a virulent swine isolate (P13) one-hundred times in laboratory culture medium was conducted to produce an ...attenuated strain, and to identify genomic determinants of virulence through comparison of genome sequences of the original and passaged strains. The resulting strain, P113, did not differ from P13 in terms of diagnostic biochemical characteristics but had an enhanced growth rate in culture, indicating laboratory adaptation. Whole genome sequencing of P113 revealed several single-nucleotide changes including a T to C transition that results in an R to G amino acid change in a putative mannose-1-phosphate guanylytransferase that is implicated in production of lipo-oligosaccharide. P113 was partially attenuated in a mouse model of infection, indicated by significantly fewer observations of abnormal feces in mice infected with P113 relative to P13. No differences were detected in bacterial shedding in feces, demonstrating that the ability of the organism to colonize mice was not affected. Passage through a mouse did not further alter the virulence of P113. Results of this study provide insight into genomic determinants of virulence in B. hampsonii and a live attenuated vaccine candidate.
Background
Most interactions between pathogenic microorganisms and their target host occur on mucosal surfaces of internal organs such as the intestine. In vitro organ culture (IVOC) provides an ...unique tool for studying host-pathogen interactions in a controlled environment. However, this technique requires a complex laboratory setup and specialized apparatus. In addition, issues arise when anaerobic pathogens are exposed to the hyperoxic environment required for intestinal culture. The objective of this study was to develop an accessible 3D–printed device that would allow manipulation of the gas mixture used to supply the tissue culture media separately from the gas mixture exposed to the mucosal side of explants.
Results
Porcine colon explants from 2 pigs were prepared (
n
= 20) and cultured for 0h, 8h, 18h and 24h using the device. After the culture period, explants were fixed in formalin and H&E stained sections were evaluated for histological defects of the mucosa. At 8h, 66% of samples displayed no histological abnormalities, whereas samples collected at 18h and 24h displayed progressively increasing rates of superficial epithelial erosion and epithelial metaplasia.
Conclusions
The 3D–design reported here allows investigators to setup intestinal culture explants while manipulating the gas media explants are exposed to, to support tissue viability for a minimal of 8h. The amount of media necessary and tissue contamination are potential issues associated with this apparatus.
Swine dysentery is causally associated with Brachyspira hampsonii and B. hyodysenteriae infection. Given the importance of transmission models in understanding re-emergent diseases and developing ...control strategies such as vaccines, the objective of this experiment was to evaluate two experimental natural transmission (seeder pig) models in grower pigs, each with 24 animals. Seeder pigs were intragastrically inoculated using broth cultures of either B. hampsonii strain 30446 (genomovar II) or B. hyodysenteriae strain G44. In trial 1, three seeder pigs were placed into two pens containing nine susceptible contact pigs creating a 1:3 seeder:contact ratio. This was sufficient to achieve natural B. hampsonii infection of 13/18 (72%) contact pigs, however, the incidence of mucoid or mucohemorrhagic diarrhea (MMHD) in contact pigs differed significantly between pens (4/9 versus 9/9; P = 0.03). In trial 2, eight seeder pigs inoculated intragastrically with B. hampsonii did not develop MMHD but when re-inoculated with B. hyodysenteriae 14 days later, all developed mucohemorrhagic diarrhea within 13 days of re-inoculation. Two seeder pigs were placed into each of 4 contact pens each containing 4 pigs. This 1:2 seeder:contact ratio resulted in natural infection of 14/16 (87%) contact pigs with incubation period ranging from 9-15 days. There were no significant differences among pens in incubation period, duration, clinical period or severity of diarrhea. These trials demonstrated that a 1:2 seeder:contact ratio with groups of six grower pigs per pen sustained natural transmission of B. hyodysenteriae G44 with greater consistency in the incidence of MMHD among pens compared to a B. hampsonii 30446 transmission model using 1:3 seeder:contact ratio in pens of 12. Understanding why B. hampsonii intragastric inoculation failed in one experiment warrants additional research.
In 2019, Streptococcus equi subsp. zooepidemicus was recognized as an emerging pathogen of swine, associated with sudden deaths, increased abortion rates and septicaemia. Limited data are available ...regarding this disease in pigs. The objectives of this study were to clarify clinical progression, pathogen shedding, transmission, gross and microscopic lesions following infection in pigs. Six weeks old pigs were inoculated with either S. zooepidemicus sequence type 194 (inoculated, n = 6) or sham inoculated with sterile culture broth (sentinels, n = 4). Animals were housed in the same room, in two pens 2 m apart. Pigs were monitored twice daily for clinical signs, and rectal, nasal and oral swabs were collected once daily. A full necropsy was performed if welfare was a concern or at 5 days post‐inoculation (dpi). All sentinels remained disease free and their samples tested negative for the pathogen of interest. All inoculated pigs developed fever within 8 h of inoculation, and severe disease was observed after 2 dpi. A total of 4/6 inoculated pigs developed clinical signs that compromised animal welfare and were euthanized. Nasal swabs (15/23), followed by rectal swabs (9/23) yield the highest number of positive ante‐mortem samples. Clinically healthy, inoculated pigs had detectable levels of S. zooepidemicus in rectal and nasal swabs. Reactive submandibular lymph nodes, kidney petechiae and splenomegaly were found in six of six inoculated pigs. These data suggest that subclinically infected pigs may spread the pathogen through nasal secretions and faeces. Direct contact seems to be required for transmission.
Streptococcus equi subsp. zooepidemicus is an emerging pathogen of pigs, resulting in high-mortality outbreaks of septicaemia and abortions. Here, we investigated the early pathogenesis of S. ...zooepidemicus in pigs following oronasal inoculation. Fourteen pigs were inoculated with live cultures of S. zooepidemicus ST-194, and monitored at 2,4, 8, and 24 h post-inoculation. Necropsies were performed to assess gross lesions and collect samples for bacterial culture and PCR analysis at each time point. Our findings revealed that S. zooepidemicus was detectable in various organs as early as 2 h post-inoculation, including liver and spleen, demonstrating rapid dissemination within the host. Tonsil samples consistently harboured live S. zooepidemicus throughout the study period, suggesting their potential for epidemiological sampling and diagnostics. Moreover, the presence of varying bacterial loads in mesenteric lymph nodes indicated persistence, replication, and a potential source for shedding. Further studies are required to determine the initial site of replication.
•ETN is suggested as an infectious disease, not related to viruses.•Intradermal inoculation triggers the initial lesions characteristic of ETN and resulted in partial loss of pinnae cartilage.•The ...full aetiology, particularly related to progression, remains unclear.
Swine ear-tip necrosis (ETN) is a disease of global presence and unclear aetiology. Little evidence is available regarding the nature of this disease. The aim of this work was to investigate if ETN is an infectious disease that could be replicated using a lesion macerate inoculum.
A source farm with a history of ear-tip necrosis was identified and five weeks-old pigs (n = 12) from this farm were housed under controlled conditions and intradermally inoculated with ETN lesion macerates (right ear, n = 10) or sterile inoculum (left ear, n = 10). Two pigs were not inoculated, serving as sentinels. All animals were clinically monitored daily during 21 days, and a ETN ear score was used to follow disease progression. Anaerobic (n = 2) and aerobic (n = 2) overnight cultures, as well as raw aliquots of the lesion macerate inoculum (n = 2) and control inoculum (n = 2) were submitted for metagenomic sequencing. All inoculated ears developed lesions suggestive of early ETN, but none progressed to result in loss of the ear pinna. All completely resolved 21 days post-inoculation. Post-mortem investigation revealed areas of fibrosis, characterized by a granulomatous response in the inoculated ears (5/10) and in 1/10 control ears. Metagenomic analysis identified the presence of previously suggested bacterial etiological agents, but no relevant viral, fungal or protozoan agents in the inoculum. ETN etiology remains unclear, but an infectious cause and bacterial agents are suggested to be at least partially implicated in disease pathogenesis. Virus and fungi do not seem to significantly contribute to disease.
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