Campylobacter jejuni is the leading cause of bacterial gastroenteritis in the U.S., with an estimated cost of treatment and loss of productivity exceeding $1 billion annually. Epidemiologic case studies have linked campylobacteriosis to the handling and consumption of contaminated poultry. Despite many advances in the understanding of C. jejuni virulence, there is still much that is not understood about the mechanisms of pathogenesis. Because of this, there is still no effective vaccine in poultry against C. jejuni. Interventions at the level of the farm, poultry processing plant, and consumer have failed to eliminate the risk of C. jejuni infection from raw chicken. Thus the development of a vaccine is critical to improve food safety. Pili play an important role in the attachment of the bacterium to the host cell and are therefore considered important vaccine targets. Previous work in the laboratory indicates the presence of fibers disseminating from a strain of C. jejuni incapable of producing flagella. Further investigation and annotation analysis of sequences identified the formation and function of a type IV pilus, leading to the hypothesis that Cj1343c gene is the major pilin subunit. The purpose of this project is to test the hypothesis by 1) generating an isogenic mutant of the putative pilA (Cj1343c) gene in NCTC 11168 flaAB mutant (NCTC 11168 flaAB:pilA double mutant) to confirm the loss of pili by scanning electron microscopy, 2) by generating an isogenic mutant of putative pilA (Cj1343c) gene in the wild-type NCTC 11168 (NCTC 11168 putative pilA (Cj1343c) mutant) to investigate the gene's role in various virulence assays, 3) to attach gold beads to the expressed pilus from the NCTC 11168 flaAB mutant to confirm that the putative pilA (Cj1343c) gene is the major pilin subunit and 4) to characterize the role of the putative pilA (Cj1343c) gene in various virulence assays. Assessing the role of the putative pili in the colonization of poultry will contribute significant knowledge regarding virulence in C. jejuni, and determine whether Cj1343c would be a viable vaccine target. If so, pili vaccines have proved successful for other pathogens and an effective C. jejuni vaccine for poultry would be significant in preventing campylobacteriosis.