RESUMEN
Enterotoxigenic Escherichia coli (ETEC) is the major diarrhoea-causing pathogen world-wide. Fimbria-receptor recognition is the primary step when attachment of ETEC to the intestine occurs. This study aims to evaluate the potential of some traditional foods, particularly those rich in ß-glucans, as analogues for fimbriae or receptors in reducing ETEC colonisation. The adhesion test (AT) demonstrated that aqueous extracts of highland barley (EHB), black rice (EBR) and little millet (ELT) at concentrations of 2% and 1% could attach to more ETEC K88ac (p < 0.001), as well as aqueous extracts of shiitake (EST) (p < 0.01). The competition test (CT) revealed that EHB and EST significantly prevented ETEC K88ac from adhering to intestinal epithelial cells (IPEC-J2) at 2% (p < 0.01) and 1% (p < 0.05). In the Exclusion Test (ET) and the displacement test (DT), the food samples were unable to impair ETEC colonisation in terms of blocking receptors or removing attached pathogens. These results demonstrate how some traditional foods such as highland barley and shiitake contain bioactive compounds that interfere with the attachment of ETEC to the intestinal epithelium, and their potential in the prevention and treatment of ETEC diarrhoea.
RESUMEN
Enterotoxigenic Escherichia coli (ETEC) is an important type of pathogenic bacteria that causes diarrhea in humans and young livestock. The pathogen has a high morbidity and mortality rate, resulting in significant economic losses in the pig industry. To effectively prevent piglet diarrhea, we developed a new tetravalent genetically engineered vaccine that specifically targets ETEC. To eliminate the natural toxin activity of ST1 enterotoxin and enhance the preventive effect of the vaccine, the mutated ST 1, K88ac, K99, and LT B genes were amplified by PCR and site-specific mutation techniques. The recombinant strain BL21(DE3)(pXKK3SL) was constructed and achieved high expression. Animal experiments showed that the inactivated vaccine had eliminated the natural toxin activity of ST1. The immune protection test demonstrated that the inclusion body and inactivated vaccine exhibited a positive immune effect. The protection rates of the inclusion body group and inactivated vaccine group were 96 and 98%, respectively, when challenged with 1 minimum lethal dose, indicating that the constructed K88ac-K99-3ST1-LTB vaccine achieved a strong immune effect. Additionally, the minimum immune doses for mice and pregnant sows were determined to be 0.2 and 2 mL, respectively. This study suggests that the novel K88ac-K99-3ST1-LTB vaccine has a wide immune spectrum and can prevent diarrhea caused by ETEC through enterotoxin and fimbrial pathways. The aforementioned research demonstrates that the K88ac-K99-3ST1-LTB vaccine offers a new genetically engineered vaccine that shows potential for preventing diarrhea in newborn piglets.
RESUMEN
To develop an attenuated vaccine candidate against K88ac enterotoxigenic Escherichia coli (ETEC), a novel Escherichia coli (E. coli) K88ac LT(S63K)ΔSTb with LT(S63K) mutation and ST1 deletion was generated using site mutagenesis and λ-Red homologous recombination based on wild paternal ETEC strain C83902. E. coli K88ac LT(S63K)ΔSTb showed very similar fimbriae expression and growth kinetics to the wild strain C83902, but it was significantly attenuated according to the results of a rabbit ligated ileal loop assay and mouse infection study. Oral inoculation with E. coli K88ac LT(S63K)ΔSTb stimulated the mucosa immune response and induced the secretion of IgA to K88ac in the intestines in mice. A challenge experiment revealed that the attenuated strain provided efficient protection against C83902 in the following 7 days and at the 24th day post-inoculation, suggesting that the attenuated isolate could act as an ecological protectant and vaccine in preventing K88ac ETEC.
RESUMEN
The study evaluated whether a transgenic carrot vaccine could induce a K88-specific immune response in sows and whether the resultant maternal antibody could protect piglets against enterotoxigenic Escherichia coli (ETEC) K88ac infection. Sows (n = 15) selected randomly from a farm in Korea were assigned to three groups (n = 5 per group: control [untreated]), group A (orally inoculated with a non-transgenic and transgenic carrot vaccines at 2 and 4 weeks ante partum, respectively), and group B (conventionally vaccinated according to the manufacturer's instructions). After 7 days of lactation, 5 piglets selected randomly from each group were challenged with 1 x 1010 colony forming units/mL ETEC K88ac. Group C had the lowest mean fecal consistency score on post-challenge days 1 and 7. Histiologically, On post-challenge day 7, group C showed an increased duodenum and ileum villus:crypt ratio, compared to group A in the duodenum, with group B displaying the highest ratio. Groups B and C had more increased villus width than group A in the jejunum. Group C displayed the greatest increase in villus width in the ileum. The colostrums and serum from groups B and C displayed higher concentrations of IgA and IgG against ETEC K88, compared to group A. Based on the results, it was concluded that the transgenic carrot vaccine in sow per oral may have an effect on preventing piglet diarrhea as good as commercial recombinant vaccine.