Enteroxigenic Escherichia coli (ETEC) is the most common cause of diarrhea in developing countries and in travelers to these areas. We study the prevalence of such bacteria and their virulence factors in different countries and populations, using specific monoclonal antibody and molecular diagnostic methods (e.g. gene probes and PCR). We also analyze the expression of different ETEC virulence factors during clinical infection as compared to during growth in vitro, and we try to identify protective immune mechanisms against ETEC both in animal studies and by studying infections and re-infections with ETEC in birth cohort studies, e.g. in Bangladesh.
Work is also in progress to develop an effective ETEC vaccine. Studies are in progress to evaluate the influence of different nutritional factors including breastfeeding for vaccine efficacy. These studies are conducted in close collaboration with scientists in different developing countries, e.g. in Bangladesh, Egypt, Guatemala, Mexico and Bolivia.
Since H. pylori is one of the most common gastrointestinal infections that primarily infect young children, in particular in developing countries, we are studying infection with these bacteria and development of immune responses during the first years of life in a high endemic area. This includes studies to evaluate the role of maternal immunity and also if protective immunity can develop in young infants that may explain spontaneous eradication. We are also comparing mucosal immune responses in Swedish and Bangladeshi asymptomatic carriers and duodenal ulcer patients as a background for development of an H. pylori vaccine that can be used worldwide.
Lundgren A, Trollmo C, Edebo A, Svennerholm A-M and Lundin BS. (2005) Helicobacter pylori-specific CD4+ T cells home to and accumulate in the; human helicobacter-infected gastric mucosa. Infect Immun 73:5612-5619
Qadri F, Ahmed T, Ahmed F, Begum YA, Sack DA and Svennerholm A-M. (2006) Reduced doses of oral killed enterotoxigenic Escherichia coli plus cholera toxin B subunit vaccine is safe and immunogenic in Bangladeshi children 6 months to 12 years of age: dosing studies in different age groups. Vaccine 24:1726-33.