Oral immunization against enterotoxigenic colibacillosis in weaned piglets by non-pathogenic Escherichia colistrain with K88 (F4) colonizing factors

Abstract

Experiments were focused on the prevention of diarrhoea in weaned piglets by means of enterotoxigenic strains of Escherichia coli (ETEC) with colonizing factors K88 (F4). The process of immunization consisted of intramuscular administration of ETEC strain bacterin one day prior to weaning and oral administration of a live culture of non-pathogenic E. coli strain containing colonizing factors (O149:K88; STa-, LT-) in 3 hours after weaning. The shedding of the K88 positive E. coli strains was monitored for 3 weeks after weaning by the culture of rectal swabs. The efficacy of such immunization protocol was tested by challenge exposure to enterotoxigenic E. coli O149:K88, LT+ strain on the third or the tenth day after weaning. Following the oral administration of non-pathogenic E. coli strain containing colonizing factors K88 to piglets, the shedding of the administered strain continued for 9 days. No or very small protection against diarrhoea following the challenge exposure to enterotoxigenic E. coli was found in immunized piglets.

Evidence-Based Approaches for Determining Effective Target Antigens to Develop Vaccines against Post-Weaning Diarrhea Caused by Enterotoxigenic Escherichia coli in Pigs: A Systematic Review and Network Meta-Analysis

“…This disease leads to significant economic losses due to the high mortality rate, weight loss, treatment cost, and growth retardation it causes in piglets. Enterotoxigenic Escherichia coli (ETEC) possess fimbrial antigens (adhesins) that mediate bacterial colonization by binding to specific receptors on intestinal epithelial cells [ 2 , 3 ]. ETEC, which express F4 (K88) or F18 adhesive fimbriae, are considered the main causative agents for PWD [ 4 , 5 , 6 , 7 ].…”

“…F4/F18 fimbriae and enterotoxins are crucial virulence factors involved in disease pathogenesis. Vaccination of pregnant sows imparts passive colostral and lactogenic immunity in piglets, which helps to control neonatal diarrhea [ 2 , 8 ]. However, as passive lactogenic immunity is gradually lost with age and is terminated completely during the weaning period [ 2 , 9 ], newly weaned piglets are highly vulnerable to ETEC infections.…”

“…Vaccination of pregnant sows imparts passive colostral and lactogenic immunity in piglets, which helps to control neonatal diarrhea [ 2 , 8 ]. However, as passive lactogenic immunity is gradually lost with age and is terminated completely during the weaning period [ 2 , 9 ], newly weaned piglets are highly vulnerable to ETEC infections. Furthermore, several studies indicate that the swine genotype may affect the susceptibility or resistance of pigs toward ETEC infection.…”