Original scientific paper

https://doi.org/10.24099/vet.arhiv.1584

Evaluation of the prophylactic potential of non-enterotoxigenic Escherichia coli (non-ETEC) vaccine immunization and dietary mannan oligosaccharide competitive exclusion benefits against ETEC infections in weaned pigs

Hrvoje Valpotić ; Department of Animal Nutrition and Dietetics, Faculty of Veterinary Medicine, University of Zagreb,Croatia
Davor Svoboda ; Ministry of Agriculture, Fisheries and Rural Development of Croatia, Zagreb Croatia
Daniel Špoljarić ; Department of Veterinary Biology, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Denis Leiner ; Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Branimira Špoljarić ; Clinic for Obstetrics and Reproduction, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Nada Vijtiuk ; Faculty of Teacher Education, University of Zagreb, Zagreb, Croatia
Boris Habrun ; Croatian Veterinary Institute, Zagreb, Croatia
Hrvoje Capak ; Department of Radiology, Ultrasound Diagnostic and Physical Therapy, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Željko Vidas ; Department of Urology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia
Silvijo Vince ; Clinic for Obstetrics and Reproduction, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Nino Maćešić ; Clinic for Obstetrics and Reproduction, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Marko Samardžija ; Clinic for Obstetrics and Reproduction, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Maja Popović ; Department of Veterinary Biology, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Ana Kovšca Janjatović ; University of Applied Health Sciences, Zagreb, Croatia
Gordana Lacković ; Department of Biology, Faculty of Science, University of Zagreb, Croatia
Ivica Va
Martina Đurić Jarić ; Krka d.d., Zagreb, Croatia
Franjo Marković ; Belupo d.d. Koprivnica, Croatia

Abstract

Enterotoxigenic Escherichia coli (ETEC) strains expressing F4 and F18 fimbriae are the most common causative
agents of post-weaning diarrhoea (PWD) in pigs. The growing global restriction on the use of antibiotics in food
animals has encouraged research into the development of nutritional and feeding strategies as well as vaccination
against PWD. The aim of this study was to evaluate the efficacy of a live oral F4ac+ F18ac+ non-ETEC vaccine candidate
(VAC) to stimulate gut and systemic cellular immunity in 4-week old pigs over 5 weeks following immunization. The onset and duration of protective immunity against on-farm occurring PWD, growth performance, diarrhoea scoring
and mortality, as well as the phenotypic proportions of immune cells, were determined. Faecal and ileal samples
were taken for determining the microbial composition or phenotyping of naïve/memory T cells. Also, the effect of
prebiotic supplement mannan oligosaccharide (MOS) in the prevention of small intestinal colonization by ETEC, and
its potential adjuvanticity in combination with the vaccine (VAC+MOS) were assessed. The pigs supplemented with
MOS or that received VAC had significantly higher body weight (BW) (P<0.05) on Day 14, whereas the VAC+MOS
treated pigs had significantly lower BW on Day 35. Treatment with VAC+MOS resulted in considerably reduced
clinical PWD, in particular the incidence and severity of diarrhoea and mortality. The total bacterial load in the ileum
was much lower in the pigs from all 3 principal groups (MOS, VAC, and VAC+MOS) than in the control (CON) group
(19 x 107, 17 x 107 and 12 x 107 vs. 23 x 108 CFU/mL, respectively) on Day 35. The pigs from the principal groups had
significantly higher proportions of tested immune cells (P<0.05) on Days 28 and 35. The localization and frequency of
naive CD45RA+ and memory CD45RC+ T lymphocytes indicated their different distribution patterns within particular
tissue structures, such as the villi, crypts, epithelium, lamina propria and areas (interfollicular follicular and Peyer’s
patches) of ileal mucosa. This may indicate their different functions in intestinal immune responses to intraluminal
microbes and their products, vaccinal immunogens and/or immunomodulators/adjuvants. To conclude, active mucosal
immunity is needed to protect pigs against PWD. Hence, oral vaccination of pigs against both F4 and F18 ETEC, in
combination with prebiotic supplementation represents a sustainable, practical and effective approach in PWD control.

Keywords

immunization; Escherichia coli; competitive exclusion; mannan oligosaccharide; pigs

Hrčak ID:

274813

URI

https://hrcak.srce.hr/274813

Publication date:

24.3.2022.

Article data in other languages: croatian

Visits: 512 *