Mississippi State University
Kiess, Aaron S.
Adhikari, Pratima A.
Other Advisors or Committee Members
Date of Degree
Dissertation - Campus Access Only
Doctor of Philosophy (Ph.D)
College of Agriculture and Life Sciences
Department of Poultry Science
Campylobacteriosis is a leading foodborne illness worldwide, primarily caused by Campylobacter jejuni (C. jejuni) which is associated with poultry consumption. The emergence of antibiotic resistance has emphasized the need for alternative strategies to control C. jejuni colonization in poultry. To assess the prevalence of C. jejuni in poultry, 270 cloacal swab samples were collected from broilers raised under No-Antibiotics Ever system. Among these samples, 16.3% were identified as C. jejuni positive. Notably, these isolates exhibited a diverse range of virulence factors and antimicrobial resistance genes, with 61.36% of isolates showing hyper-motile and 20.45% demonstrating multidrug resistance. Following isolation, whole genome sequencing was conducted on four selected strains using a hybrid sequencing approach. Subsequently, the complete genomes of these C. jejuni strains were analyzed to identify vaccine candidates using reverse vaccinology. Three conserved potential vaccine candidates were identified as suitable targets for vaccine development, namely phospholipase A (PldA), TonB dependent transporter (ChuA), and cytolethal distending toxin (CdtB). Furthermore, the gene expression of these candidates was examined in four C. jejuni strains during host-pathogen interactions using avian macrophage cell line HD11. Significant upregulation of all three candidate genes were observed in the four tested C. jejuni strains during interaction with host cells, indicating their crucial role in C. jejuni infection. Additionally, the expression of immune genes was evaluated in avian macrophage cells to understand the immune responses during C. jejuni infection. The infection resulted in the upregulation of toll-like receptor genes (TLR-4), pro-inflammatory genes (IL-1β, IFN-γ, IL-6, IL-8L1), anti-inflammatory gene (IL-10), and iNOS2 gene expression. The observed immune response demonstrates the potential of C. jejuni to induce host immunity for protection. In conclusion, our study identifies three conserved potential vaccine candidates and provides insights into the immune responses induced by C. jejuni infection in avian macrophage cells. These findings are crucial for the development of an effective vaccine against C. jejuni, aiming to reduce C. jejuni transmission through poultry consumption and the risk of human infection.
Poudel, Sabin, "Use of comparative genomics and in vitro screening approach to identify vaccine candidates for the food-borne pathogen Campylobacter jejuni" (2023). Theses and Dissertations. 5949.