Shigellae belong to the Gram-negative group of bacteria and are the causative agent of shigellosis or bacillary dysentery. The genus Shigella contains four species - S. dysenteriae, S. flexneri, S. boydii and S. sonnei. Two species in particular, S. dysenteriae type 1 and S. flexneri, cause acute diarrhoeal illness which often results in chronic infection especially in malnourished infants and children.
Each year there are approximately 165 million cases of shigellosis throughout the world causing 1.1 million deaths. S. flexneri is the predominant species in endemic areas and the principal cause of morbidity and mortality in young children in developing countries. The infectivity of the disease is very high with oral-faecal person-to-person spread the most important mode of transmission. As hygiene standards and sanitary facilities in developing countries are not likely to improve in the near future, the development of effective vaccines is vital for the control and prevention of shigellosis. A number of approaches have been used in the past but no effective vaccine is available for prevention of shigellosis at present.
My group is involved in identifying novel virulence factors and studying their potential as vaccine targets for the development of both live and subunit vaccines against shigellosis.