Commensal or pathogen – a challenge to fulfil Koch’s Postulates

ABSTRACT

1. Infectious diseases have a large impact on poultry health and economics. Elucidating the pathogenesis of a certain disease is crucial to implement control strategies.

2. Multiplication of a pathogen and its characterisation in vitro are basic requirements to perform experimental studies. However, passaging of the pathogen in vitro can influence the pathogenicity, a process targeted for live vaccine development, but limits the reproduction of clinical signs.

3. Numerous factors can influence the outcome of experimental infections with some importance on the pathogen, application route and host as exemplarily outlined for Histomonas meleagridis, Gallibacterium anatis and fowl aviadenoviruses (FAdVs).

4. In future, more comprehensive and detailed settings are needed to obtain as much information as possible from animal experiments. Processing of samples with modern diagnostic tools provides the option to closely monitor the host–pathogen interaction.

Acknowledgements

The author would like to thank the Robert Fraser Gordon Memorial Trust and the Trustees for being nominated to present the Gordon Memorial Lecture in 2016. Special thanks to all coworkers and cooperation partners, their contribution was vital for the success of the referenced studies. The substantial contribution of various funding agencies was crucial to transfer certain ideas from theory into practice.

Disclosure statement

No potential conflict of interest was reported by the author.