Exploration of Vaccine Candidates against Avian Pathogenic E. coli Using Proteome Mining

Avian Pathogenic Escherichia coli (APEC) is a major causative agent of avian colibacillosis, causing significant financial losses to the poultry industry.Current vaccines offer limited protection and also pose logistical challenges related to storage and administration.Considering this fact, a subtractive proteome analysis along with a reverse vaccinology approach was performed for the screening of promising vaccine candidates that would offer broad protection against heterologous serotypes of APEC.O1, O2, and O78 are APEC's most prevalent and pathogenic serotypes, responsible for over 80% of infections in poultry.Therefore, the essential, highly virulent, and strongly antigenic outer membrane proteins (OMPs) shared among these pathogenic serotypes of APEC were screened through comprehensive In Silico analysis.Thus, six OMPs were identified as viable vaccine targets, including OmpA, PapC, Wza, YehB, PhoE, and EtsC.These OMPs belong to the four functional families: outer membrane protectin, transporters, capsular biogenesis, and fimbrial biogenesis.Afterwards, a novel chimeric vaccine was designed against APEC by using four B-cell, four CTL, and five HTL epitopes, which were highly conserved among the three highly pathogenic serotypes.Molecular docking and dynamic simulations revealed the stable and high-affinity interactions between the constructed chimeric vaccine and the mammalian TLR4 receptor.Nonetheless, in vitro and in vivo experimental validation will be required to confirm the immunogenicity and protective efficacy of the vaccine ensemble.