Assessment of an Enterobactin Conjugate Vaccine in Layers to Protect Their Offspring from Colibacillosis

Abstract

Colibacillosis, caused by avian pathogenic Escherichia coli (APEC), is an important infectious disease in chickens and a major cause of mortality in young chicks. Therefore, protecting young chickens from colibacillosis is important for improving welfare and productivity in the poultry industry. Recently, we developed a novel enterobactin (Ent) conjugate vaccine that could induce high titers of anti-Ent immunoglobulin Y (IgY) in chicken serum and consequently mitigate the organ lesions caused by APEC infection. Considering that maternal immunization is a practical approach to confer instant immune protection to the hatchlings, in this study, we immunized breeder hens with the Ent conjugate vaccine and evaluated the maternal immune protection on the progenies challenged with APEC. Three doses of the vaccine induced high titers of anti-Ent IgY in the hens (about 16- and 64-fold higher than the control group in the sera and egg yolks, respectively), resulting in an eight-fold of increase in anti-Ent IgY in the sera of progenies. However, the anti-Ent maternal immunity did not display significant protection against APEC challenge in the young chicks as there was no significant difference in APEC load (in liver, lung, and spleen) or organ lesions (in heart, liver, spleen, lung, and air sac) between the vaccinated and control groups. In future studies, the APEC infection model needs to be optimized to exhibit proper pathogenicity of APEC, and the maternal immunization regimen can be further improved to boost the maternally derived anti-Ent IgY in the hatchlings.

Positive Assessment of an Autogenous Vaccine Against Pathogenic Escherichia coli in Broiler Breeders and their Progeny in Morocco

“…The transfer of IgY induced by immunization from a hens' serum to the vitellus of her eggs is well described and industrially used for egg-yolk antibody production (for a review, see [17]). Also, the transfer of anti-APEC maternal antibodies to their progeny after vaccination has been demonstrated under experimental conditions, with the use of a candidate enterobactin conjugate vaccine [9]. Furthermore, broiler chickens were proven protected by passive immunity further to the immunization of their female ascendants with an autogenous inactivated vaccine under experimental conditions [14].…”

“…Commercial APEC vaccines are available as a preventative strategy against colibacillosis; they also contribute to limiting the use of antibiotics; however, their efficacy is often limited by the lack of cross-protection between heterologous APEC strains [7]. This has led to a paradigm change in the poultry industry, that now considers the use of autogenous vaccines an innovative solution and a part of the strategy to prevent and control avian colibacillosis, including protecting the progeny of vaccinated breeding hens [8], leading the way to new vaccine development [9].…”