Maternal immunity enhances systemic recall immune responses upon oral immunization of piglets with F4 fimbriae

Abstract

F4 enterotoxigenic Escherichia coli (ETEC) cause diarrhoea and mortality in piglets leading to severe economic losses. Oral immunization of piglets with F4 fimbriae induces a protective intestinal immune response evidenced by an F4-specific serum and intestinal IgA response. However, successful oral immunization of pigs with F4 fimbriae in the presence of maternal immunity has not been demonstrated yet. In the present study we aimed to evaluate the effect of maternal immunity on the induction of a systemic immune response upon oral immunization of piglets. Whereas F4-specific IgG and IgA could be induced by oral immunization of pigs without maternal antibodies and by intramuscular immunization of pigs with maternal antibodies, no such response was seen in the orally immunized animals with maternal antibodies. Since maternal antibodies can mask an antibody response, we also looked by ELIspot assays for circulating F4-specific antibody secreting cells (ASCs). Enumerating the F4-specific ASCs within the circulating peripheral blood mononuclear cells, and the number of F4-specific IgA ASCs within the circulating IgA+ B-cells revealed an F4-specific immune response in the orally immunized animals with maternal antibodies. Interestingly, results suggest a more robust IgA booster response by oral immunization of pigs with than without maternal antibodies. These results demonstrate that oral immunization of piglets with F4-specific maternal antibodies is feasible and that these maternal antibodies seem to enhance the secondary systemic immune response. Furthermore, our ELIspot assay on enriched IgA+ B-cells could be used as a screening procedure to optimize mucosal immunization protocols in pigs with maternal immunity.

Application of High Energy and Protein Diets in Combination with a Live Avirulent Escherichia coli F4 Vaccine Against Post-Weaning Diarrhea

“…Therefore, E. coli F4 vaccination might be one of the alternative strategies once ZnO is banned in the EU by 2022. Besides vaccination, several other alternative strategies, such as adapted nutritional strategies (feed consistency, lower crude protein, digestible fibers and other dietary fibers), prebiotics, probiotics, organic acids, MCFAs, specific IgA antibodies and oral vaccination have been explored [19][20][21][22][23][24][25][26][27][28][29]33,34,[38][39][40][41].…”

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

“…In addition to piglet screening for pathogen susceptibility, the pathogen-specific immunization of piglets and sows should be evaluated. In fact, beyond the passive immunity derived from sow’s milk which can affect the piglet’s responsiveness to ETEC immediately after weaning, it has been shown that maternal immunity can persist in piglet blood and can induce a systemic immune response in the piglets [83], resulting in a less efficient piglet response to the ETEC challenge. Therefore, in studies where feeding strategies with the aim of contracting the ETEC infection, selecting piglets from sows not specifically immunized for ETEC and not infected with the pathogen previously has been recommended.…”

“…Therefore, in studies where feeding strategies with the aim of contracting the ETEC infection, selecting piglets from sows not specifically immunized for ETEC and not infected with the pathogen previously has been recommended. For studies where vaccine strategies are tested, the passage of maternal immunization should be considered for a correct interpretation of the results, as suggested by Nguyen et al [83].…”

Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea

“…Therefore, alternative approaches to control PWD due to pathogenic E. coli should be explored. Several alternative strategies, such as adapted nutritional strategies (feed consistency, lower crude protein, digestible fibers and other dietary fibers), prebiotics, probiotics, organic acids, MCFAs, specific IgA antibodies and oral vaccination have been explored [19][20][21][22][23][24][25][26][27][28][29]33,34,[37][38][39][40]].…”