REVERSE VACCINOLOGY APPROACH FOR IDENTIFICATION AND PRIORITIZATION OF ANTIGEN CANDIDATES FOR A VACCINE AGAINST A POULTRY PATHOGEN

MARIA ESPERANZA FELICI; YOSEF HUBERMAN; BELKYS MALETTO; RODRIGO QUIROGA

Congreso; LXX REUNIÓN SAI; 2022

Avibacterium paragallinarum is the causative agent of infectious coryza, an acute disease that affects the upper respiratory system of chickens. This Gram-negative bacteria is widely distributed in poultry production systems all over the world, causing significant economic losses. Despite vaccination being the main form of prevention, commercially available vaccines show incomplete protection against strains not included in the formulation.As a first step to develop a more effective vaccine, we implemented Reverse Vaccinology strategies to identify potential antigens present in 28 Av. paragallinarum strains. Comparative and subtractive genomics and prediction of several protein attributes (sequence conservation, antigenicity, essentiality, homology to the host, subcellular localization and adhesin probability, among other features) were used to narrow down and prioritize proteins with ease of expression and protection potential. To validate this computational workflow, the same pipeline was applied to a dataset of 1085 proteins with experimentally known antigenicity, collected from published literature and various antigen and/or epitope databases. Among the possible antigens (~4% of each strain proteome), 25 proteins were conserved in all strains. Outer membrane protein assembly factor BamA, porin OmpA, TolC family protein, translocation-assembly module TamB and LPS assembly protein LptD were classified as the most prominent candidates qualifying all the set criteria. Furthermore, more than 27% of the positive control dataset were correctly identified as potentially protective antigens. Despite the imposed restrictions lead to the loss of many experimentally verified antigens, the applied restrictive criteria proved to be useful for our goal of protein prioritization. Although in vivo testings are still needed, this study provides a basis for the development of a novel subunit vaccine against Av. paragallinarum.