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In the next funding period, we will extend these studies to:
<ol>
<li> assess the ability of these vaccines to confer cross-protection with different flaA types of C. jejuni, </li>
<li> determine the minimal amount of time needed post-immunization to confer protective immunity,</li>
<li> determine the minimal C. jejuni challenge dose in which complete protection occurs, </li>
<li> determine whether the bivalent vaccine confers protection against Salmonella infection and </li>
<li> determine the smallest flagellin fragment that can elicit protective immunity. An immunogenic, broadly cross-reactive vaccine should be useful in improving the safety of poultry for human consumption.</li></ol>
<P>
Campylobacter jejuni is a major cause of gastrointestinal infection in man and is the most common cause of sporadic diarrheal illness in the U.S. Campylobacter infection is primarily a foodborne disease with poultry being the single most important vehicle for transmitting the disease.</p>
<P>
A number of immunological approaches to reducing or eliminating Campylobacter from poultry are currently being investigated including the use of vaccines. The mechanism by which Campylobacter colonizes the chick GI tract is not completely understood but flagella are important colonization factors. </p>
<P>
We expressed the full length Campylobacter flagellin gene, flaA, in an avirulent Salmonella typhimurium vaccine vector and tested several vaccine constructs in 4 day old chicks for immunogenicity and protection. </p>
<P>
During the past funding period, we showed that these vaccines were highly immunogenic and induced anti-flagellin antibodies using a two-dose regimen. When animals were challenged 3 weeks after vaccination with the homologous strain of C. jejuni, vaccines conferred >95% homologous protection against cecal colonization.</p>