Methodology and application of Escherichia coli F4 and F18 encoding infection models in post-weaning pigs

Abstract

The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets. The growing global concern regarding antimicrobial resistance (AMR) has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC. A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection. Thus, the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority. The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models; it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge. Based on the current review, it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs, and the timing and dosage of the ETEC inoculation. Furthermore, the evaluation of the ETEC challenge response should include both clinical parameters (such as the occurrence of diarrhea, rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18 (such as antibody production, specific F4/F18 immunoglobulins (Igs), ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders). On the basis of the review, the piglets’ response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development, on ETEC fecal shedding and in the piglets’ immunological antibody response. This information was considered to be relevant to correctly define the experimental protocol, the data recording and the sample collections. Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement, reduction and refinement (3R) approach, and to be able to evaluate the efficiency of a given feeding, nutritional or vaccination intervention in order to combat ETEC infection.

Contribution of L-Arginine supplementation during gestation on sow productive performance and on sow microbial faecal profile

“…Considering the additional parameters related to the sows' health status collected in the present study, no effect of Arg supplementation has been observed on the salivary Igs concentration. Saliva collection has the advantage of being non-invasive sampling as it causes minimal stress during collection, thus it represents an ideal tool for stress physiology and health evaluation (Luise et al 2019b;Escribano et al 2015). The concentrations of IgA and IgG observed in the present study are in line with the values observed by Escribano et al (2012); although the diet did not affect the Igs concentrations, it is noteworthy the quadratic effect observed for the sow parity on salivary IgA, in which a maximum concentration has been observed for the third parity sows.…”

Oral Immunogenicity in Mice and Sows of Enterotoxigenic Escherichia Coli Outer-Membrane Vesicles Incorporated into Zein-Based Nanoparticles

“…These vaccines, which are mainly applied parenterally, contain different virulence factors such as fimbriae, LPS, outer membrane proteins (OMPs) and LT enterotoxins [24][25][26]. However, they tend to stimulate the systemic rather than the mucosal immune system required to provide protection against ETEC bacteria in the gut [17]. Oral immunization might overcome that problem but faces several barriers [27].…”

“…ETEC strains expressing F4 or F18 fimbriae are the most commonly associated with diarrhea in weaned pigs. The presence of F4 or f18 fimbrial adhesins has been found to be significantly correlated with pathogenicity, but there are also significant differences in host response after F4 or F18 infection, for instance, different patterns in the elicited immune response, the lapse and intensity of the symptoms (i.e., diarrhea of piglets) or the timing in the intermittent bacterial shedding have been described [17]. In this study, we propose the use of outer membrane vesicles (OMVs) from the F4 and F18 serotypes, the main ETEC strains involved in piglet infection, as the source of relevant antigens.…”

Synbiotic Effects of Enzyme and Probiotics on Intestinal Health and Growth of Newly Weaned Pigs Challenged With Enterotoxigenic F18+Escherichia coli

“…The fecal score was recorded by the same trained person from the d 3 to d 7 of the study to analyze the effects of the synbiotic in the pre-challenge period and to confirm that pigs assigned to the challenge group are in normal fecal score before the E. coli F18 + inoculation. The fecal score was also recorded from d 8 to d 20 of the study to analyze the effects of ETEC infection (24,25). The fecal score was recorded using a 1-5 scale: (1) very firm stool, (2) normal firm stool, (3) moderately loose stool, (4) loose, watery stool, and (5) very watery stool.…”