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.