Reverse vaccinology approach to identify antigens to use in a vaccine against Av. paragallinarum

MARÍA ESPERANZA FELICI; YOSEF D.HUBERMAN; BELKYS A. MALETTO; RODRIGO QUIROGA

Congreso; XI Argentine Congress of Bioinformatics and Computational Biology (XI CAB2C); 2021

Background: Avibacterium paragallinarum is the causative agent of infectious coryza, an acute disease that affects the upper respiratory system of chickens (Gallus gallus). According to Page (1962), this Gram negative bacteria may be classified into three serogroups: A, B and C. This organism is widely distributed in poultry production systems all over the world, causing significant economic losses due to diminished growth performance and egg production. Despite vaccination being the main form of prevention, currently available commercial vaccines, based on inactivated international reference strains, show only partial protection against local strains. In hopes of developing a new vaccine that overcomes this difficulty, antigens with broad protection potential were identified in silico from the three Page serogroups of Av. paragallinarum. Results: To identify antigens with vaccine candidate potential, a reverse vaccinology strategy was followed. Briefly, comparative and subtractive genomics were used in conjunction with sequence analysis to perform a sequential discard of proteins. The first elimination criteria aimed to remove proteins homologous to those of the host to avoid autoimmune reactions, following selection of the essential outer membrane proteins. Afterwards, proteins were classified according to their antigenicity. Furthermore, poorly conserved proteins among the different strains were removed from the dataset. Finally, proteins were characterized regarding their physicochemical properties, secondary structure and signal peptide presence. As a result, proteins deemed the most conserved, essential, antigenic, accessible and non-host homologous, as well as most likely to be easily expressed heterologously, were selected. Among the predicted antigens, type IV pilus biogenesis/stability protein PilW, peptidoglycan-associated lipoprotein Pal, outer membrane protein assembly factor BamE, OmpH family outer membrane protein and rod shape-determining protein MreC were identified as potential candidates qualifying all the set criteria. Conclusions: Although only a few strains were analyzed, and in vitro and in vivo testings are still needed to validate the protective effect of the newly identified antigens, this study provides a basis for the development of a novel subunit vaccine against Av. paragallinarum.