The Campylobacter jejuni Dps Homologue Is Important for<i>In Vitro</i>Biofilm Formation and Cecal Colonization of Poultry and May Serve as a Protective Antigen for Vaccination

In this work, we investigated the Campylobacter jejuni dps (DNA binding protein from starved cells) gene for a role in biofilm formation and cecal colonization in poultry. In vitro biofilm formation assays were conducted with stationary-phase cells in cell culture plates under microaerophilic conditions. These studies demonstrated a significant (>50%) reduction in biofilm formation by the C. jejuni dps mutant compared to that by the wild-type strain. Studies in poultry also demonstrated the importance of the dps gene in host colonization by C. jejuni. Real-time PCR analysis of mRNA extracted from the cecal contents of poultry infected with wild-type C. jejuni indicated that the dps gene is upregulated 20-fold during poultry colonization. Cecal colonization was greater than 5 log CFU lower in chicks infected with the dps mutant than chicks infected with the wild-type C. jejuni strain. Moreover, the dps mutant failed to colonize 75% of the chicks following challenge with 10(5) CFU. Preliminary studies were conducted in chicks by parenteral vaccination with a recombinant Dps protein or through oral vaccination with a recombinant attenuated Salmonella enterica strain synthesizing the C. jejuni Dps protein. No reduction in C. jejuni was noted in chicks vaccinated with the parenteral recombinant protein, whereas, a 2.5-log-unit reduction of C. jejuni was achieved in chicks vaccinated with the attenuated Salmonella vector after homologous challenge. Taken together, this work demonstrated the importance of Dps for biofilm formation and poultry colonization, and the study also provides a basis for continued work using the Dps protein as a vaccine antigen when delivered through a Salmonella vaccine vector.