Abstract
Brachyspira pilosicoli is a potentially zoonotic anaerobic intestinal spirochaete that is one of several species causing avian intestinal spirochaetosis. The aim of this study was to develop a reproducible model of infection in point of lay chickens and compare the virulence of two strains of B. pilosicoli in a model using experimentally challenged laying chickens. Seventeen week-old commercial laying chickens were experimentally challenged by oral gavage with either B. pilosicoli strain B2904 or CPSp1, following an oral dose of 10% sodium bicarbonate to neutralise acidity in the crop. Approximately 80% of the chickens became colonised and exhibited increased faecal moisture content, reduced weight gain and delayed onset of lay. Tissues sampled at post-mortem examination were analysed to produce a quantitative output on the number of spirochaetes present and hence, the extent of colonisation. The liver and spleen were colonised and novel histopathology was observed in these tissues. The infection model we report here has potential use in studies to improve our understanding of the mechanisms by which Brachyspira elicit disease in poultry and in testing novel intervention strategies.