Reverse vaccinology and host-pathogen analysis reveal pagP as a potential universal vaccine candidate against avian...

Avian pathogenic Escherichia coli (APEC) causes colibacillosis, requiring effective vaccines to prevent this devastating disease in poultry. Current strain-specific vaccines show limited protection against diverse APEC strains, highlighting the need to identify conserved antigens for broad-protective vaccine development. This study combines reverse vaccinology (RV) analysis of APEC whole-genome sequences with host-pathogen interaction studies to identify universal vaccine candidates, their expression, and effect on host immune responses. These complementary approaches aim to identify and select potential antigens for the development of broad-spectrum vaccines against APEC infections in poultry.

A total of 3061 core genome protein coding sequences were predicted from 25 APEC isolates, including 44 proteins that met the criteria of subcellular localization (extracellular and outer membrane), number of transmembrane helix (0 or 1), and adhesion probability score (≥ 0.5). Among them, 32 proteins were antigenic (antigen score ≥ 0.5) and highly conserved across the E. coli database. Finally, 13 vaccine candidates were predicted to have the immunogenicity potential. During the host-pathogen interaction studies, selected E. coli isolates induced a host immune reaction (all with P ≤ 0.01), and among the 13 predicted vaccine candidates, pagP showed a highly upregulated expression level during the interaction (P ≤ 0.01).

In this study, pagP was identified as having the most potential for future development of recombinant vaccines against APEC.