Carrier state of enterotoxigenic Escherichia coli virulence markers in pigs: Effects on gut microbiota modulation and immune markers transcription.

Enterotoxigenic Escherichia coli (ETEC) causes diarrhea in pigs at early age, leading to high mortality rates and significant economic losses in the swine industry. ETEC effect on gut microbiota and immune system is mostly studied in diarrheic model under controlled laboratory conditions, however its impact on asymptomatic carriers remains unknown. Thus, we investigated whether ETEC can modulate gut microbiota or regulate the transcription of immune markers in asymptomatic pigs in farm environment. Stool samples from newborn piglets, nursery and growing pigs, and sows were screened for ETEC markers, then submitted to 16S-rDNA sequencing to explore gut microbiota composition in carriers (ETEC+) and non-carriers (ETEC-) animals. We observed a reduced α-diversity in ETEC+ animals (p < 0.05), while bacterial compositions were mostly driven by ageing (p > 0.05). Prevotella marked ETEC-carrier group, while Rikenellaceae RC9 gut group was a marker for a healthy gut microbiota, suggesting that they might be biomarker candidates for surveillance and supplementation purposes. Furthermore, we observed transcription regulation of il6 and tff2 genes in ETEC+ in newborn and nursery stages, respectively. Our findings indicate that ETEC presence modulate gut microbiota and the immune response in asymptomatic pigs; nevertheless, further studies using a probabilistic design must be performed to assess the effect of ETEC presence on gut imbalance in pigs despite the age bias.

The colonization factor CS6 of enterotoxigenic Escherichia coli contributes to host cell invasion.

Enterotoxigenic Escherichia coli (ETEC) is one of the main causes of diarrhea in children and travelers in low-income regions. The virulence of ETEC is attributed to its heat-labile and heat-stable enterotoxins, as well as its colonization factors (CFs). CFs are essential for ETEC adherence to the intestinal epithelium. However, its invasive capability remains unelucidated. In this study, we demonstrated that the CS6-positive ETEC strain 4266 can invade mammalian epithelial cells. The invasive capability was reduced in the 4266 ΔCS6 mutant but reintroduction of CS6 into this mutant restored the invasiveness. Additionally, the laboratory E. coli strain Top 10, which lacks the invasive capability, was able to invade Caco-2 cells after gaining the CS6-expressing plasmid pCS6. Cytochalasin D inhibited cell invasion in both 4266 and Top10 pCS6 cells, and F-actin accumulation was observed near the bacteria on the cell membrane, indicating that CS6-positive bacteria were internalized via actin polymerization. Other cell signal transduction inhibitors, such as genistein, wortmannin, LY294002, PP1, and Ro 32-0432, inhibited the CS6-mediated invasion of Caco-2 cells. The internalized bacteria of both 4266 and Top10 pCS6 strains were able to survive for up to 48 h, and 4266 cells were able to replicate within Caco-2 cells. Immunofluorescence microscopy revealed that the internalized 4266 cells were present in bacteria-containing vacuoles, which underwent a maturation process indicated by the recruitment of the early endosomal marker EEA-1 and late endosomal marker LAMP-1 throughout the infection process. The autophagy marker LC3 was also observed near these vacuoles, indicating the initiation of LC-3-associated phagocytosis (LAP). However, intracellular bacteria continued to replicate, even after the initiation of LAP. Moreover, intracellular filamentation was observed in 4266 cells at 24 h after infection. Overall, this study shows that CS6, in addition to being a major CF, mediates cell invasion. This demonstrates that once internalized, CS6-positive ETEC is capable of surviving and replicating within host cells. This capability may be a key factor in the extended and recurrent nature of ETEC infections in humans, thus highlighting the critical role of CS6.

Lactobacillus plantarum and Lactobacillus brevis Alleviate Intestinal Inflammation and Microbial Disorder Induced by ETEC in a Murine Model.

The purpose of this research is to explore the positive effects of Lactobacillus plantarum and Lactobacillus brevis on the tissue damage and microbial community in mice challenged by Enterotoxigenic Escherichia coli (ETEC). Twenty-four mice were divided into four groups randomly: the CON group, ETEC group, LP-ETEC group and LB-ETEC group. Our results demonstrated that, compared with the ETEC group, the LP-ETEC and LB-ETEC groups experienced less weight loss and morphological damage of the jejunum. We measured proinflammatory factors of colonic tissue and found that L. plantarum and L. brevis inhibited the expression of proinflammatory factors such as IL-ß, TNF-α, and IL-6 and promoted that of the tight junction protein such as claudin-1, occludin, and ZO-1. Additionally, L. plantarum and L. brevis altered the impact of ETEC on the intestinal microbial community of mice, significantly increased the abundance of probiotics such as Lactobacillus, and reduced that of pathogenic bacteria such as Proteobacteria, Clostridia, Epsilonproteobacteria, and Helicobacter. Therefore, we believe that L. plantarum and L. brevis can stabilize the intestinal microbiota and inhibit the growth of pathogenic bacteria, thus protecting mice from the gut inflammation induced by ETEC.

Effects of IQW and IRW on Inflammation and Gut Microbiota in ETEC-Induced Diarrhea.

METHODS: The mice were randomly distributed into four groups: (a) control (CTRL) group, (b) ETEC group, (c) IQW-ETEC group, and (d) IRW-ETEC group. Villus length and crypt depth were measured after hematoxylin and eosin staining. The inflammatory reaction was analyzed via inflammatory cytokines (i.e., TNF-α, IL-1ß, IL-6, and IL-10) using the enzyme-linked immunosorbent assay (ELISA). The microbiota in the colon was sequenced using 16S ribosomal RNA. RESULTS: The villus length decreased, the crypt depth decreased, and the expression of inflammatory cytokines (i.e., TNF-α, IL-1ß, IL-6, and IL-10) increased due to ETEC. In the IRW-ETEC and IQW-ETEC groups, the Shannon index decreased (P < 0.05). IQW and IRW increased the abundance of Firmicutes, Proteobacteria, Clostridiales, Lachnospiraceae, and Alloprevotella; contrastingly, it decreased the abundance of Epsilonproteobacteria, Erysipelotrichales, Prevotellaceae, and Flavobacteriaceae compared to the ETEC group (P <0.05). CONCLUSION: This study ascertained that the addition of IQW and IRW could alleviate jejunal inflammation and increase microbiota community diversity.

Changing the locks on intestinal signaling.

Endogenous peptides and structurally similar bacterial heat-stable enterotoxins (ST) bind guanylate cyclase-C (GC-C), resulting in fluid homeostasis or diarrhea, respectively. In this issue of Cell Host & Microbe, Carey et al., show how bats have evolutionarily maintained homeostatic signaling while avoiding pathogenic effects of ST.

Protective Effects of Selenium Nanoparticle-Enriched Lactococcus lactis NZ9000 against Enterotoxigenic Escherichia coli K88-Induced Intestinal Barrier Damage in Mice.

Composite microecological agents have received widespread attention due to their advantageous properties, including safety, multiple effects, and low cost. This study was conducted to evaluate the protective effects of selenium (Se) nanoparticle (SeNP)-enriched Lactococcus lactis NZ9000 (L. lactis NZ9000-SeNPs) against enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal barrier damage in C57BL/6 mice. The oral administration of L. lactis NZ9000-SeNPs significantly increased the villus height and the number of goblet cells in the ileum; reduced the levels of serum and ileal interleukin-1ß (IL-1ß), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ); and increased the activities of thioredoxin reductase (TrxR) and glutathione peroxidase (GSH-Px) compared with the ETEC K88-infected group not treated with L. lactis NZ9000-SeNPs. In addition, L. lactis NZ9000-SeNPs significantly attenuated the reduction of the expression levels of occludin and claudin-1, dysbiosis of the gut microbiome, and activation of the Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB)-mediated signaling pathway induced by ETEC K88. These findings suggested that L. lactis NZ9000-SeNPs may be a promising and safe Se supplement for food or feed additives. IMPORTANCE The beneficial effects of microecological agents have been widely proven. Se, which is a nutritionally essential trace element for humans and animals, is incorporated into selenoproteins that have a wide range of pleiotropic effects, ranging from antioxidant to anti-inflammatory effects. However, sodium selenite, a common addition form of Se in feed and food, has disadvantages such as strong toxicity and low bioavailability. We investigated the protective effects of L. lactis NZ9000-SeNPs against ETEC K88-induced intestinal barrier injury in C57BL/6 mice. Our results show that L. lactis NZ9000-SeNPs effectively alleviate ETEC K88-induced intestinal barrier dysfunction. This study highlights the importance of developing a promising and safe Se supplement for the substitution of sodium selenite applied in food, feed, and biomedicine.

In Vitro Evaluation of Dietary Fiber Anti-Infectious Properties against Food-Borne Enterotoxigenic Escherichia coli.

Dietary fibers have well-known beneficial effects on human health, but their anti-infectious properties against human enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is the main agent of travelers' diarrhea, against which targeted preventive strategies are currently lacking. ETEC pathogenesis relies on multiple virulence factors allowing interactions with the intestinal mucosal layer and toxins triggering the onset of diarrheal symptoms. Here, we used complementary in vitro assays to study the antagonistic properties of eight fiber-containing products from cereals, legumes or microbes against the prototypical human ETEC strain H10407. Inhibitory effects of these products on the pathogen were tested through growth, toxin production and mucus/cell adhesion inhibition assays. None of the tested compounds inhibited ETEC strain H10407 growth, while lentil extract was able to decrease heat labile toxin (LT) concentration in culture media. Lentil extract and specific yeast cell walls also interfered with ETEC strain H10407 adhesion to mucin beads and human intestinal cells. These results constitute a first step in the use of dietary fibers as a nutritional strategy to prevent ETEC infection. Further work will be dedicated to the study of fiber/ETEC interactions within a complex gut microbial background.

Diarrheal pathogens trigger rapid evolution of the guanylate cyclase-C signaling axis in bats.

The pathogenesis of infectious diarrheal diseases is largely attributed to enterotoxins that cause dehydration by disrupting intestinal water absorption. We investigated patterns of genetic variation in mammalian guanylate cyclase-C (GC-C), an intestinal receptor targeted by bacterially encoded heat-stable enterotoxins (STa), to determine how host species adapt in response to diarrheal infections. Our phylogenetic and functional analysis of GC-C supports long-standing evolutionary conflict with diarrheal bacteria in primates and bats, with highly variable susceptibility to STa across species. In bats, we further show that GC-C diversification has sparked compensatory mutations in the endogenous uroguanylin ligand, suggesting an unusual scenario of pathogen-driven evolution of an entire signaling axis. Together, these findings suggest that conflicts with diarrheal pathogens have had far-reaching impacts on the evolution of mammalian gut physiology.

Ligilactobacillus salivarius Strains Isolated From the Porcine Gut Modulate Innate Immune Responses in Epithelial Cells and Improve Protection Against Intestinal Viral-Bacterial Superinfection.

Previously, we constructed a library of Ligilactobacillus salivarius strains from the intestine of wakame-fed pigs and reported a strain-dependent capacity to modulate IFN-ß expression in porcine intestinal epithelial (PIE) cells. In this work, we further characterized the immunomodulatory activities of L. salivarius strains from wakame-fed pigs by evaluating their ability to modulate TLR3- and TLR4-mediated innate immune responses in PIE cells. Two strains with a remarkable immunomodulatory potential were selected: L. salivarius FFIG35 and FFIG58. Both strains improved IFN-ß, IFN-λ and antiviral factors expression in PIE cells after TLR3 activation, which correlated with an enhanced resistance to rotavirus infection. Moreover, a model of enterotoxigenic E. coli (ETEC)/rotavirus superinfection in PIE cells was developed. Cells were more susceptible to rotavirus infection when the challenge occurred in conjunction with ETEC compared to the virus alone. However, L. salivarius FFIG35 and FFIG58 maintained their ability to enhance IFN-ß, IFN-λ and antiviral factors expression in PIE cells, and to reduce rotavirus replication in the context of superinfection. We also demonstrated that FFIG35 and FFIG58 strains regulated the immune response of PIE cells to rotavirus challenge or ETEC/rotavirus superinfection through the modulation of negative regulators of the TLR signaling pathway. In vivo studies performed in mice models confirmed the ability of L. salivarius FFIG58 to beneficially modulate the innate immune response and protect against ETEC infection. The results of this work contribute to the understanding of beneficial lactobacilli interactions with epithelial cells and allow us to hypothesize that the FFIG35 or FFIG58 strains could be used for the development of highly efficient functional feed to improve immune health status and reduce the severity of intestinal infections and superinfections in weaned piglets.

Antibacterial and Antibiofilm Activities of Novel Antimicrobial Peptides against Multidrug-Resistant Enterotoxigenic Escherichia Coli.

Post-weaning diarrhea due to enterotoxigenic Escherichia coli (ETEC) is a common disease of piglets and causes great economic loss for the swine industry. Over the past few decades, decreasing effectiveness of conventional antibiotics has caused serious problems because of the growing emergence of multidrug-resistant (MDR) pathogens. Various studies have indicated that antimicrobial peptides (AMPs) have potential to serve as an alternative to antibiotics owing to rapid killing action and highly selective toxicity. Our previous studies have shown that AMP GW-Q4 and its derivatives possess effective antibacterial activities against the Gram-negative bacteria. Hence, in the current study, we evaluated the antibacterial efficacy of GW-Q4 and its derivatives against MDR ETEC and their minimal inhibition concentration (MIC) values were determined to be around 2~32 µg/mL. Among them, AMP Q4-15a-1 with the second lowest MIC (4 µg/mL) and the highest minimal hemolysis concentration (MHC, 256 µg/mL), thus showing the greatest selectivity (MHC/MIC = 64) was selected for further investigations. Moreover, Q4-15a-1 showed dose-dependent bactericidal activity against MDR ETEC in time-kill curve assays. According to the cellular localization and membrane integrity analyses using confocal microscopy, Q4-15a-1 can rapidly interact with the bacterial surface, disrupt the membrane and enter cytosol in less than 30 min. Minimum biofilm eradication concentration (MBEC) of Q4-15a-1 is 4× MIC (16 µg/mL), indicating that Q4-15a-1 is effective against MDR ETEC biofilm. Besides, we established an MDR ETEC infection model with intestinal porcine epithelial cell-1 (IPEC-1). In this infection model, 32 µg/mL Q4-15a-1 can completely inhibit ETEC adhesion onto IPEC-1. Overall, these results suggested that Q4-15a-1 may be a promising antibacterial candidate for treatment of weaned piglets infected by MDR ETEC.

Screening of probiotic candidates in a simulated piglet small intestine in vitro model.

The CoMiniGut in vitro model mimicking the small intestine of piglets was used to evaluate four probiotic strains for their potential as a preventive measure against development of diarrhea in weaned pigs. In the in vitro system, piglet digesta was inoculated with pathogenic enterotoxigenic Escherichia coli F4 (ETEC F4), and the short-chain fatty acid profile and the gut microbiota composition were assessed. A total of four probiotic strains were evaluated: Enterococcus faecium (CHCC 10669), Lactobacillus rhamnosus (CHCC 11994), Bifidobacterium breve (CHCC 15268) and Faecalibacterium prausnitzii (CHCC 28556). The significant differences observed in metabolite concetration and bacterial enumeration were attributed to variation in inoculating material or pathogen challenge rather than probiotic treatment. Probiotic administration influenced the microbiota composition to a small extend. Learnings from the present study indicate that the experimental setup, including incubation time and choice of inoculating material, should be chosen with care.

Aetiology of acute diarrhoea in children in Shanghai, 2015-2018.

Diarrhoea remains a major cause of childhood morbidity and mortality worldwide. This study aimed to monitor the aetiology of acute diarrhoea in children in Shanghai. Paediatric outpatients with acute diarrhoea were enrolled in the study from Jan 2015 to Dec 2018. Faecal samples were collected for testing. Enteric bacteria were identified and typed by culture and serotyping, respectively. Enteric viruses were identified by real-time PCR. Enteric pathogens were identified in 1572 (58.4%) of the 2692 enrolled children with acute diarrhoea. Viruses were detected more frequently than bacteria (41.3% versus 25.0%). Nontyphoidal Salmonella spp. (NTS) was the most common (10.3%) bacteria isolated, followed by enteropathogenic Escherichia coli (EPEC) (6.5%), enteroaggregative Escherichia coli (EAEC) (6.2%), Campylobacter spp. (3.6%), enterotoxigenic Escherichia coli (ETEC) (1.1%), Shigella spp. (0.2%), and enterohemorrhagic Escherichia coli (EHEC) (0.1%). Rotavirus was the most common (16.0%) virus detected, followed by norovirus (15.5%), adenovirus (7.2%), sapovirus (3.0%) and astrovirus (2.7%). Rotavirus, norovirus and NTS were the major pathogens responsible for diarrhoea in Shanghainese children. Improving uptake of the rotavirus vaccine and strengthening foodborne-pathogen prevention will aid in reducing the burden of diarrhoeal disease in children in Shanghai.

Virulence and antimicrobial resistance genes are enriched in the plasmidome of clinical Escherichia coli isolates compared with wastewater isolates from western Kenya.

Many low-middle income countries in Africa have poorly-developed infectious disease monitoring systems. Here, we employed whole genome sequencing (WGS) to investigate the presence/absence of antimicrobial resistance (AMR) and virulence-associated (VA) genes in a collection of clinical and municipal wastewater Escherichia coli isolates from Kakamega, west Kenya. We were particularly interested to see whether, given the association between infection and water quality, the isolates from these geographically-linked environments might display similar genomic signatures. Phylogenetic analysis based on the core genes common to all of the isolates revealed two broad divisions, corresponding to the commensal/enterotoxigenic E. coli on the one hand, and uropathogenic E. coli on the other. Although the clinical and wastewater isolates each contained a very similar mean number of antibiotic resistance-encoding genes, the clinical isolates were enriched in genes required for in-host survival. Furthermore, and although the chromosomally encoded repertoire of these genes was similar in all sequenced isolates, the genetic composition of the plasmids from clinical and wastewater E. coli was more habitat-specific, with the clinical isolate plasmidome enriched in AMR and VA genes. Intriguingly, the plasmid-borne VA genes were often duplicates of genes already present on the chromosome, whereas the plasmid-borne AMR determinants were more specific. This reinforces the notion that plasmids are a primary means by which infection-related AMR and VA-associated genes are acquired and disseminated among these strains.

Molecular mechanism of Escherichia coli H10407 induced diarrhoea and its control through immunomodulatory action of bioactives from Simarouba amara (Aubl.).

Enterotoxigenic Escherichia coli (ETEC) infection is a major cause of death in children under the age of five in developing countries. ETEC (O78:H11:CFA/I:LT+:ST+) mechanism has been studied in detail with either heat labile (LT) or heat stable (ST) toxins using in vitro and in vivo models. However, there is no adequate information on ETEC pathogenesis producing both the toxins (LT, ST) in BALB/c mice model. In this study, female mice have been employed to understand ETEC H10407 infection induced changes in physiology, biochemical and immunological patterns up to seven days post-infection and the antidiarrhoeal effect of Simarouba amara (Aubl.) bark aqueous extract (SAAE) has also been looked into. The results indicate that BALB/c is sensitive to ETEC infection resulting in altered jejunum and ileum histomorphology. Withal, ETEC influenced cAMP, PGE2, and NO production resulting in fluid accumulation with varied Na+, K+, Cl-, and Ca2+ levels. Meanwhile, ETEC subverted expression of IL-1ß, intestine alkaline phosphatase (IAP), and myeloperoxidase (MPO) in jejunum and ileum. Our data also indicate the severity of pathogenesis reduction which might be due to attainment of equilibrium after reaching optimum rate of infection. Nevertheless, degree of pathogenesis was highly significant (p < 0.01) in all the studied parameters. Besides that, SAAE was successful in reducing the infectious diarrhoea by inhibiting ETEC H10407 in intestine (jejunum and ileum), and shedding in feces. SAAE decreased cAMP, PGE2, and fluid accumulation effectively and boosted the functional activity of immune system in jejunum and ileum IAP, MPO, IL-1ß, and nitric oxide.

A new multidrug-resistant enterotoxigenic Escherichia coli pulsed-field gel electrophoresis cluster associated with enrofloxacin non-susceptibility in diseased pigs.

AIMS: To describe the temporal trends in Escherichia coli pathotypes and antimicrobial resistance detected in isolates from diseased-pig cases submitted to the EcL from 2008 to 2016, in Quebec, Canada, and to investigate the presence of spatiotemporal and phylogenetic clusters. METHODS AND RESULTS: Detection of 12 genes coding for virulence factors in pathogenic E. coli in pigs by PCR and antimicrobial resistance standard disc diffusion assay were performed. Demographic and clinical data were entered in the Animal Pathogenic and Zoonotic E. coli (APZEC) database. ETEC:F4 was the most prevalent pathovirotype among the 3773 cases submitted. The LT:STb:F4 virotype was predominant until 2014, then was overtaken by the LT:STb:STa:F4 virotype. More than 90% of the ETEC:F4 isolates were multidrug resistant. A spatiotemporal cluster of LT:STb:STa:F4 isolates non-susceptible to enrofloxacin was detected between 4/2015 and 9/2016. Pulsed-field gel electrophoresis analysis of 137 ETEC:F4 isolates revealed the presence of a cluster composed mainly of LT:STb:STa:F4 isolates non-susceptible to enrofloxacin. CONCLUSIONS: The APZEC database was useful to highlight temporal trends in E. coli pathotypes. A high-risk ETEC:F4 clone might disseminate in the pig population in Quebec since 2015. SIGNIFICANCE AND IMPACT OF THE STUDY: Surveillance is crucial to identify new clones and develop control strategies.

Lactobacillus plantarum inhibited the inflammatory response induced by enterotoxigenic Escherichia coli K88 via modulating MAPK and NF-κB signalling in intestinal porcine epithelial cells.

AIMS: To investigate the effects of Lactobacillus plantarum on inflammatory responses induced by ETEC K88 and explore the underlying molecular mechanisms. METHODS AND RESULTS: Intestinal porcine cells (IPEC-1) were incubated with 0 or 1 × 108  CFU per well L. plantarum for 4 h, and then these cells were challenged with 0 or 1 × 108  CFU per well ETEC K88 for 2 h. The results showed that pre-treatment of IPEC-1 cells with L. plantarum prevented the increases in the transcript abundance of interleukin-1α (IL-1α), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α) (P < 0·05) caused by ETEC K88. Additionally, L. plantarum inhibited the reduction in peroxisome proliferator-activated receptor-γ (PPAR-γ) expression caused by ETEC K88 (P < 0·05). Moreover, L. plantarum pre-treatment downregulated the phosphorylation levels of c-Jun N-terminal kinase (JNK), extracellular regulated protein kinases 1 and 2 (ERK1/2) and p38 and the nuclear concentration of nuclear factor kappa B p65 (NF-κB p65) (P < 0·05) compared with ETEC K88 group. Silencing experiment further supported that the protective effect of L. plantarum P might mediated by suppression of ETEC-provoked activation of MAPK and NF-κB signalling pathways. CONCLUSIONS: Lactobacillus plantarum inhibited the inflammatory response induced by ETEC K88 in IPEC-1 cells via modulating MAPK and NF-κB signalling. SIGNIFICANCE AND IMPACT OF THE STUDY: This study elucidated the underlying mechanism in which probiotics protect against intestinal inflammation caused by ETEC K88.

Heat-stable enterotoxin inhibits intestinal stem cell expansion to disrupt the intestinal integrity by downregulating the Wnt/ß-catenin pathway.

Enterotoxigenic Escherichia coli causes severe infectious diarrhea with high morbidity and mortality in newborn and weanling pigs mainly through the production of heat-stable enterotoxins (STs). However, the precise regulatory mechanisms involved in ST-induced intestinal epithelium injury remain unclear. Consequently, we conducted the experiments in vivo (mice), ex vivo (mouse and porcine enteroids), and in vitro (MODE-K and IPEC-J2 cells) to explore the effect of STp (one type of STa) on the integrity of the intestinal epithelium. The results showed that acute STp exposure led to small intestinal edema, disrupted intestinal integrity, induced crypt cell expansion into spheroids, and downregulated Wnt/ß-catenin activity in the mice. Following a similar trend, the enteroid-budding efficiency and the expression of Active ß-catenin, ß-catenin, Lgr5, PCNA, and KRT20 were significantly decreased after STp treatment, as determined ex vivo. In addition, STp inhibited cell proliferation, induced cell apoptosis, destroyed cell barriers, and reduced Wnt/ß-catenin activity by downregulating its membrane receptor Frizzled7 (FZD7). In contrast, Wnt/ß-catenin reactivation protected the IPEC-J2 cells from STp-induced injury. Taking these findings together, we conclude that STp inhibits intestinal stem cell expansion to disrupt the integrity of the intestinal mucosa through the downregulation of the Wnt/ß-catenin signaling pathway.

Evaluation of the probiotic and functional potential of Lactobacillus agilis 32 isolated from pig manure.

Escherichia coli is a symbiotic bacterium in humans and animals and an important pathogen of humans and animals. Prevention and suppression of E. coli infection is of great concern. In this study, we isolated a strain of Lactobacillus agilis 32 from pig manure and evaluated its biological characteristics, and found that its bacterial survival rate was 25% after 4 h of treatment at pH 2, and under the condition of 0·5% bile concentration, its survival rate exceeds 30%. In addition, L. agilis 32 has a cell surface hydrophobicity of 77·8%, and exhibits 67·1% auto-aggregation and 63·2% aggregation with Enterotoxigenic E. coli 10 (ETEC 10). FITC fluorescence labelling showed that the fluorescence intensity of cecum was significantly higher than that of duodenum, jejunum or colon (P < 0·05), but no significant difference from ileum. Lactobacillus agilis 32 bacterial culture and CFS showed average inhibition zone diameters of 14·2 and 15·4 mm respectively. Lactobacillus agilis 32 CFS treatment can significantly reduce the pathogenicity of ETEC 10. These results show that L. agilis 32 is an active and potential probiotic, and it has a good antibacterial effect on ETEC10, which provides basic research for probiotics to prevent and treat intestinal diarrhoea pathogen infection.

Establishment and Validation of Pathogenic CS17+ and CS19+ Enterotoxigenic Escherichia coli Challenge Models in the New World Primate Aotus nancymaae.

Enterotoxigenic Escherichia coli (ETEC) is a common cause of diarrheal illness in the military, travelers, and children living in low- to middle-income countries. Increased antibiotic resistance, the absence of a licensed vaccine, and the lack of broadly practical therapeutics perpetuate the significant health and financial burden resulting from ETEC infection. A critical step in the evaluation of vaccines and therapeutics is preclinical screening in a relevant animal disease model that closely replicates human disease. We previously developed a diarrheal model of class 5a colonization factor (CF) CFA/I-expressing ETEC in the New World owl monkey species Aotus nancymaae using ETEC strain H10407. In order to broaden the use of the model, we report here on the development of A. nancymaae models of ETEC expressing the class 5b CFs CS17 and CS19 with strains LSN03-016011/A and WS0115A, respectively. For both models, we observed diarrheal attack rates of ≥80% after oral inoculation with 5 × 1011 CFU of bacteria. These models will aid in assessing the efficacy of future ETEC vaccine candidates and therapeutics.

Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial.

BACKGROUND: Human challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6+LT+ST+) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea. METHODS: An initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 108 or 109 colony forming units (cfu) or a 90-minute fast at doses of 109 or 1010 cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed. RESULTS: Among subjects receiving 108 cfu of B7A, overnight fast, or 109 cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 109 cfu, overnight fast, or 1010 cfu, 90-minute fast. Upon rechallenge with 109 cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups. CONCLUSIONS: An overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.