Effects of Kudoa septempunctata genotype ST3 isolate from Korea on ddY suckling mice

Kudoa septempunctata Spores Cause Acute Gastroenteric Symptoms in Mouse and Musk Shrew Models as Evidenced In Vitro in Human Colon Cells

Kudoa septempunctata is a myxosporean parasite that infects the trunk muscles of olive flounder (Paralichthys olivaceus) and has been reported to cause foodborne illnesses in humans. However, the molecular mechanisms underlying K. septempunctata spore toxicity remain largely unknown. In this study, the gastroenteropathy of K. septempunctata was examined in human colon adenocarcinoma cells as well as experimental mice inoculated with spores. We found that K. septempunctata decreased transepithelial resistance and disrupted epithelial tight junctions by deleting ZO-1 in Caco-2 monolayers. Additionally, serotonin (5-HT), an emetic neurotransmitter, was increased in K. septempunctata-inoculated cells. In vivo, K. septempunctata spores induced diarrhea in suckling mice (80% in ddY and 70% in ICR mice), with a minimum provocative dose of 2 × 10⁵ K. septempunctata spores. In house musk shrews, K. septempunctata induced emesis within 1 h and induced serotonin secretion in the intestinal epithelium. In conclusion, K. septempunctata may induce diarrhea and emesis by increasing intestinal permeability and serotonin secretion.

Immune-triggering effect of the foodborne parasite Kudoa septempunctata through the C-type lectin Mincle in HT29 cells

Kudoa septempunctata is a myxozoan parasite that causes food poisoning in individuals consuming olive flounder. The present study aimed to investigate the currently insufficiently elucidated early molecular mechanisms of inflammatory responses in the intestine owing to parasite ingestion. After Kudoa spores were isolated from olive flounder, HT29 cells were exposed to spores identified to be alive using SYTO-9 and propidium iodide staining or to antigens of Kudoa spores (KsAg). IL-1β, IL-8, TNF-α and NFKB1 expression and NF-κB activation were assessed using real-time PCR, cytokine array and western blotting. The immunofluorescence of FITC-conjugated lectins, results of ligand binding assays using Mincle-Fc and IgG-Fc, CLEC4E expres-sions in response to KsAg stimulation, and Mincle-dependent NF-κB activation were assessed to clarify the early immunetriggering mechanism. Inflammatory cytokines (IL-1β, GM-CSF and TNF-α), chemokines (IL-8, CCL2, CCL5 and CXCL1) and NF-κB activation (pNF-κB/NF-κB) in HT29 cells increased following stimulation by KsAg. The immunofluorescence results of spores and lectins (concanavalin A and wheat germ agglu-tinin) suggested the importance of Mincle in molecular recog-nition between Kudoa spores and intestinal cells. Practically, data for Mincle-Fc and KsAg binding affinity, CLEC4E mRNA expression, Mincle immunofluorescence staining and hMincle-dependent NF-κB activation demonstrated the involvement of Mincle in the early immune-triggering mechanism. The present study newly elucidated that the molecular recognition and immune-triggering mechanism of K. septempunctata are associated with Mincle on human intestinal epithelial cells.

Kudoa ogawai (Myxosporea: Kudoidae) Infection in Cultured Olive Flounder Paralichthys olivaceus

Since Kudoa septempuntata was identified as a causative agent of food poisoning associated with raw olive flounder Paralichthys olivaceus, interest and concern regarding the parasite have increased. However, there have been no investigations or reports of other Kudoa species infecting the fish (except for K. paralichthys, which infects the brain) in Korea. We found cysts filled with myxospores of Kudoa species in muscles of cultured olive flounder specimens and identified these to the species level. Mature spores were quadrate, measuring 8.7±0.5 μm in length, 9.2±0.4 μm in thickness, and 12.9±0.6 μm in width. The spores containing 4 polar capsules had a length of 2.1±0.2 μm and a width of 1.8±0.3 μm. The partial 18S and 28S rDNA of isolates showed 99–100% similarities with K. ogawai. Using these morphological and molecular analyses, the species was identified as K. ogawai. This study is the first report of K. ogawai infection in cultured olive flounder in Korea.

Foodborne Illness Outbreaks in Gyeonggi Province, Korea, Following Seafood Consumption Potentially Caused by Kudoa septempunctata between 2015 and 2016

OBJECTIVES

Investigations into foodborne illness, potentially caused by Kudoa septempunctata, has been ongoing in Korea since 2015. However, epidemiological analysis reporting and positive K septempunctata detection in feces in Korea has been limited. The aim of this study was to provide epidemiologic data analysis of possible food poisoning caused by K septempunctata in Korea.

METHODS

This study reviewed 16 Kudoa outbreak investigation reports, including suspected cases between 2015 and 2016 in Gyeonggi province, Korea. Suspected Kudoa foodborne illness outbreak was defined as "evidence of K septempunctata in at least one sample." The time and place of outbreak, patient symptoms and Kudoa (+) detection rate in feces was analyzed.

RESULTS

Kudoa foodborne illness outbreaks occurred in most patients in August (22.6%) and in most outbreaks in April (25%). The attack rate was 53.9% and the average attack rate in patients who had consumed olive flounder was 64.7%. The average incubation period was 4.3 hours per outbreak. Diarrhea was the most common symptom which was reported by 91.5% patients. The Kudoa (+) detection rate in feces was 69.2% of cases.

CONCLUSION

Monthly distribution of Kudoa foodborne illness was different from previous studies. The Kudoa (+) detection rate in feces decreased rapidly between 25.5 and 28.5 hours of the time interval from food intake to epidemiologic survey. To identify effective period of time of investigation, we believe additional study with extended number of cases is necessary.

Evaluation of the inflammatory response to Kudoa septempunctata genotype ST3 isolated from olive flounder (Paralichthys olivaceus) in Caco-2 cells

Kudoa septempunctata (Myxosporea, Multivalvulida) is a parasite of the trunk muscle of cultured olive flounder (Paralichthys olivaceus). We investigated whether K. septempunctata genotype ST3 spores induce cell damage and the secretion of inflammatory mediators in Caco-2 cells, which exhibit characteristics similar to human intestinal epithelial cells. Purified K. septempunctata spores were heated at 95 °C for 5 min. Lactate dehydrogenase (LDH) release was measured to determine the efficacy of denaturation. Naïve and heated spores, lipopolysaccharide (positive control) and vehicle (negative control) were added to Caco-2 cells. Cells were subjected to the cytotoxic LDH assay and western blot analysis to examine the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Supernatants were collected to measure nitric oxide (NO) and prostaglandin E2 (PGE2). Most spores were denaturated by heating, and the spore morphology was found to be wrinkled with shell valves and polar capsules. In addition, cytotoxicity and inflammatory mediators, such as NO, PGE2, iNOS, and COX-2, remained unchanged in Caco-2 cells following exposure to naïve and heated spores compared with the positive controls. Collectively, the findings of this study imply that spores of K. septempunctata genotype ST3 do not cause inflammation in Caco-2 cells.

Relationship between shipping amounts of olive flounder aquacultured from Jejudo and the reported events of acute food poisoning by Kudoa septempunctata in 2015, South Korea: an ecological study

OBJECTIVES

Confirmation of Kudoa septempunctata (K. septempunctata) as the pathogenic agent causing acute food poisoning remains under debate owing to inconsistencies in the reproducibility of experimental evidence. Higher intake of olive flounder infected with K. septempunctata would result in increased diagnosis of food poisoning by K. septempunctata, if the latter was one of the causal agents of acute food poisoning. The aim was to evaluate the relationship between the shipping amount of olive flounder aquacultured from Jejudo and the incidence of K. septempunctata food poisoning in 2015, Korea.

METHODS

Data of shipping amounts between March 2014 and February 2016 and of monthly reported events of Kudoa food poisoning were taken from Jejudo Fish-Culture Fisheries Cooperatives and Korea Centers for Disease Control and Prevention, respectively. Non-parametric correlation analyses were conducted.

RESULTS

Shipping amounts indicated the seasonal changes according to variation of consumption. Spearman’s rho and Kendall’s tau-a between the monthly shipping amounts and the reported events in 2015 were 0.39 (p=0.21) and 0.27 (p=0.20), respectively.

CONCLUSIONS

An independent relationship was noted between the shipping amount and the reported events, which contrasted with the claim that the virulence of K. septempunctata caused acute food poisoning.

Immune response of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata

This study evaluated the pathophysiological, biochemical, and immunological status of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata. Flounder fish collected from Kudoa-infected and uninfected farms were confirmed by microscopic and TaqMan probe-based quantitative PCR screening. Morphological, biochemical, histological, and immune gene expression analyses were performed on uninfected and infected hosts to assess the effect of K. septempunctata. Histological studies confirmed the presence of Kudoa myxospores in the trunk muscles of infected flounder fish. Serum biochemical parameters, including the levels of myeloperoxidase activity, superoxide dismutase activity, alanine aminotransferase, alkaline phosphatase, amylase, bilirubin, total protein, cholesterol, calcium, potassium, sodium, phosphorus, glucose, and galactose, were found to exhibit no significant variations (p > 0.05) between uninfected and infected flounder fish. However, immune-related genes such as Mx, lysozyme, signal transducer and activator of transcription 1, interferon-γ, interferon regulatory factor, and tumour necrosis factor showed significantly elevated expression (p < 0.05) in the trunk muscles of infected flounder fish while no significant differences were noted in uninfected fish trunk muscle and head-kidney of infected and uninfected flounder fish.

Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis

OBJECTIVES

Recently kudoa septempuctata in olive flounders is suggested as a cause of food poisoning, however whether kudoa septempuctata can affect human gastrointestinal systems is controversial and its pathogenecity remains unclear. In view of the field epidemiology, food poisonings caused by kudoa septempuctata should be distinguished from those caused by Staphylococcus aureus and bacillus cereus.

METHODS

The statistics of food poisoning investigations published by Korea Centers for Disease Control and Prevention in 2013-2015 were reviewed. The characteristics of kudoa septempuctata food poisoning reported by Korea Centers for Disease Control and Prevention were reviewed. Information regarding clinical symptoms or epidemiology was extracted.

RESULTS

Total eleven kudoa septempuctata food poisoning cases were analyzed. Food poisonings caused by kudoa septempuctata, Staphylococcus aureus and bacillus cereus have clinical and epidemiological similarities. Forty five percent of food poisoning outbreaks occurred in Korea was concluded as unknown. The food poisoning caused by Staphylococcus aureus and bacillus cereus accounted for 4.5% (50/1,092) of all food poisoning outbreaks in Korea between 2013 and 2015.

CONCLUSIONS

This study suggests the possibilities of misdiagnosis in the investigations of food poisoning by Staphylococcus aureus and bacillus cereus with kudoa septempuctata.

In vitro effect of two commercial anti-coccidial drugs against myxospores of Kudoa septempunctata genotype ST3 (Myxozoa, Multivalvulida)

Kudoa septempunctata (Myxozoa: Multivalvulida) myxospores infect the trunk muscles of olive flounder (Paralichthys olivaceus). In this study, two popular commercially formulated anti-coccidial drugs (amprolium hydrochloride and toltrazuril) were serially diluted and incubated with purified mature Kudoa septempunctata myxospores. The viability of K. septempunctata spores was determined after a 2-day incubation followed by Hoechst 33342 and propidium iodide staining, and scanning electron microscopy. Amprolium hydrochloride significantly decreased spore viability (18% of control) at a concentration of 920 μg/mL, whereas toltrazuril showed almost no effect (83% of control). Viability of the control (untreated spores) was 90%. In vivo studies are required to confirm the efficacy of amprolium hydrochloride in fish infected with K. septempunctata myxospores on their growth and immune system performance.

Is there evidence that Kudoa septempunctata can cause an outbreak of acute food poisoning?

After publishing results of a study that revealed diarrheagenic and emetic activity in 4-5-day old mice infected with Kudoa septempunctata (K. septempunctata) spores, the Korea Centers for Disease Control and Prevention reported 11 events of "Kudoa food poisoning" in 2015. The epidemiological design of the previous study was descriptive rather than analytical; therefore, this study aimed to further investigate the pathogenicity of K. septempunctata. Academic articles showing evidence of the pathogenicity of K. septempunctata were searched via PubMed using the citation discovery tool. Information regarding the kinds of experimental animals and inoculum spores used, as well as study results were extracted. Four articles evaluating the pathogenicity of Myxospran parasites were selected; the first article suggested the pathogenicity of K. septempunctata, while the remaining three articles reported no abnormal symptoms or histopathologic changes. Our findings indicate that there is weak evidence supporting the pathogenicity of K. septempunctata. Further studies evaluating the pathogenicity of K. septempunctata are needed urgently.