Rotavirus particle. Cut-away artwork showing the structure of the rotavirus icosahedral capsid (protein coat). The capsid, which encloses the RNA (ribonucleic acid) genome, has three layers: the inner capsid (pink and white), the intermediate capsid and the outer capsid. Rotavirus infection causes vomiting and diarrhoea and is the most common cause of severe diarrhoea in children.