Dr Hold has a longstanding interest in the role of microorganisms in gastrointestinal disease, with focus on dissecting the interactions between microbes and the host. Her initial work has focussed on characterising the microbiome of the human gastrointestinal tract in health and disease and she has linked this area of research with understanding the contribution to disease development of genetic variants in innate immune receptors (Hold et al Gastro 2007, El-Omar et al Oncogene 2008, Hold et al FTR 2009 and Ng et al IAI 2010 ). This work has contributed to the understanding that genetic variants in Toll-like signalling impact not only on the ability of microbes to signal to the host but also impact on the pre-programmed inflammatory state of the host.