Is Oral Vaccination against Escherichia coli Influenced by Zinc Oxide?

BACKGROUND: Although zinc oxide has been banned at therapeutic doses in the EU, its use is still legal in most countries with industrial pig farming. This compound has been shown to be very effective in preventing E. coli-related diseases. However, another strategy used to control this pathogen is vaccination, administered parenterally or orally. Oral vaccines contain live strains, with F4 and F18 binding factors. Since zinc oxide prevents E. coli adhesion, it is hypothesised that its presence at therapeutic doses (2500 ppm) may alter the immune response and the protection of intestinal integrity derived from the vaccination of animals. METHODS: A group of piglets were orally vaccinated at weaning and divided into two subgroups; one group was fed a feed containing 2500 ppm zinc oxide (V + ZnO) for the first 15 days post-vaccination (dpv) and the other was not (V). Faeces were sampled from the animals at 6, 8, 11, 13, and 15 dpv. Unvaccinated animals without ZnO in their feed (Neg) were sampled simultaneously and, on day 15 post-vaccination, were also compared with a group of unvaccinated animals with ZnO in their feed (ZnO). RESULTS: Differences were found in E. coli excretion, with less quantification in the V + ZnO group, and a significant increase in secretory IgA in the V group at 8 dpv, which later equalised with that of the V + ZnO group. There was also some difference in IFNα, IFNγ, IL1α, ILß, and TNFα gene expression when comparing both vaccinated groups (p < 0.05). However, there was no difference in gene expression for the tight junction (TJ) proteins responsible for intestinal integrity. CONCLUSIONS: Although some differences in the excretion of the vaccine strain were found when comparing both vaccinated groups, there are no remarkable differences in immune stimulation or soluble IgA production when comparing animals orally vaccinated against E. coli in combination with the presence or absence of ZnO in their feed. We can conclude that the immune response produced is very similar in both groups.

Effect of ß-Mannanase Addition during Whole Pigs Fattening on Production Yields and Intestinal Health.

The presence of ß-mannans in feed can produce a futile and chronic immune stimulation in fattening pigs. In this trial, a 1-4-endo-D-ß-mannanase was added to the feed (HC) during growth and fattening (0.03% of Hemicell HT) and physical performance and pathological data were recorded, and intestinal integrity and immune activation were studied by molecular biomarkers, compared to a control group (CON). The treatment diet was reduced in energy content by 40 Kcal/kg NE. From each group, 113 and 112 animals housed in 8 pens were individually identified and weighed three times: at 7th, 63rd and 116th days in feed. The FCR was calculated for groups of two pens and ADG individually. There was no difference in ADG (CON = 0.836, HC = 0.818) nor in FCR between groups (p = 0.486). During growth, there was a higher frequency of normal feces in HC and there were also no differences in the frequency of gastric lesions. A significant increase in Claudin, Occludin, IFN-γ and IL8 was observed in the CON in feces and a significant decrease in IL-6 in HC. In tissues, there were differences for IL-12p40, TNF-alpha in jejunum (increased CON) and TGF-ß in ileum and jejunum, (decreased HC). The economic performance was EUR 4.7 better in the treated group. In conclusion, the addition of 1-4-endo-D-ß--mannanase to the feed with a 1.6% reduction in net energy compared to the control, allowed the animals to perform as well as the animals on the higher energy diet, with lower prevalence of diarrhea.

Oral and Parenteral Vaccination against Escherichia coli in Piglets Results in Different Responses.

The available E. coli vaccines involve two main types (inactivated and live non-pathogenic) and two routes of administration (oral and parenteral) but the mechanism by which both vaccines and routes of administration work is not yet fully elucidated. The influence of a parenteral vaccine (PV) and an oral one (OV) was studied by analyzing the gene expression of biomarkers indicating cellular infiltration (calprotectin, CAL), tight junction proteins (occludin OCL, and zonulin ZON) that maintain intestinal paracellular integration and two proinflammatory (IFN-γ) and anti-inflammatory (TGF-ß) mediator cytokines, as well as histomorphology and IgA production cell density. Differences were observed in CAL, more infiltrated in orally vaccinated animals; OCL also increased in orally vaccinated animals, and higher density of IgA-producing cells in ileum for orally vaccinated groups. Cytokine expression is also different; and there is a lower mRNA for IFN-γ in the parenteral than in the oral vaccinated animals. Finally, the villus height-to-crypt depth ratio was higher in the orally vaccinated groups. The data collectively show clear and different effects derived from the use of each type of vaccine, route of administration and regimen. The results suggest a more rapid and direct effect of oral vaccination and a state of suppression in the absence of a second oral stimulus by the pathogen.