Susceptibility of Broiler Chickens to Campylobacter: Impacts of the Gut Environment and Immune Status on Colonization (Lag Phase Project)

The aim of this project is to understand the mechanisms responsible for the “Campylobacter  free period” or “Lag phase of infection” in broilers, this is the apparent resistance to Campylobacter infection shown by birds during their first weeks of life.

Susceptibility to Campylobacter infection in housed flocks is age-dependent and dose-related, chickens are more resistant to Campylobacter when they are young, and susceptibility increases as birds grow; young chicks require higher doses for infection than older birds.

On possible explanation for this phenomenon is the presence of maternally-derived antibodies, as these may influence colonisation resistance in the first few weeks of life. Breeders are usually Campylobacter-positive and maternally derived antibodies can be found in chicks up to two weeks after hatching. Another possible explanation is that the chicken gut microbiota changes with age and that these changes have an effect on colonisation by Campylobacter. For example, the presence of an inhibitory microbiota could potentially stop Campylobacter from colonising the gut.

Our hypothesis is that interaction between gut microbiota and host immunocompetence determines Campylobacter colonisation and this may also be  influenced by bird management and the environment, which acts indirectly through either or both of these host-associated factors and it is these processes which ultimately determine the observed ‘Campylobacter-free phase’.

In this project we will determine the role of maternally-derived antibodies and microbiota changes and their interaction on Campylobacter colonisation. We will use modeling to find the links between factors that influence colonization.

Our research questions are:

Does restriction of immune capacity of breeder birds, thereby eliminating transfer of maternal immunity, affect the ability of C. jejuni to colonise their progeny?

How does the absence of both specific anti-Campylobacter and natural maternally derived antibodies affect development of chicken gut microbiota?

How does the microbiota develop as individual birds grow?

How much variation exists between individual birds in a flock and between experiments?

How successional changes of the microbiota impact Campylobacter colonisation and how does Campylobacter affects the microbiota?

How do the use of and removal of coccidiostats and changes in diet affect the development of the chicken intestinal microbiota?

Do the use and removal of coccidiostats and changes in diet affect the ability of C. jejuni to colonise the chicken intestine?

How variables found in commercial flocks impact on the immunity, gut microbiota and architecture and the interaction between them and Campylobacter colonisation?

 Image showing susceptibility to Campylobacter