Effective reduction of pathogenic Escherichia coli and long-term immunity in pigs through early parenteral vaccination

Abstract

ABSTRACT The present study aimed to examine the ability of a parenteral vaccine of direct application in suckling pigs to generate adaptive immunity against pathogenic Escherichia coli under field conditions as well as the long-term immune response at the end of productive life and the influence on the prevalence of pathogens involved in the Porcine Enteric Disease Complex (PEDC). Pigs were divided into vaccinated (n = 1,893) and non-vaccinated (control, n = 1,869) groups. We collected fecal swabs from nursery pigs presenting diarrhea and intestinal tissue at slaughter to assess E. coli virulence factors genes, PEDC pathogens, histology, IgA-producing cells, and cytokines levels. Fecal swabs: vaccinated group 0% pathogenic E. coli vs. 94.1% in control (p < 0.0001). Intestinal samples: Vaccinated group 35% positivity for E. coli vs. 85% in control (p = 0.001). PEDC pathogens: Only Lawsonia intracellularis was identified (40% of ileum and 20% of colon samples in vaccinated vs. 100% of ileum and 70% of colon in the control). Vaccinated had more intestine cellular infiltrate (p < 0.028), IgA-producing cells (p < 0.01), and inflammatory cytokines. The parenteral vaccine against E. coli for suckling pigs may be a strategy to control E. coli infection throughout pigs’ lives and our results suggest a possible interaction with L. intracellularis.