[1] Queen Mary Univ London, Sch Biol & Chem Sci, Nanchang Joint Programme, London, England
[2] Univ Verona, Dept Diagnost & Publ Hlth, Microbiol Sect, Verona, Italy
[3] Univ Bologna, Dept Expt Diagnost & Specialty Med, Bologna, Italy
[4] Univ Birmingham, Inst Immunol & Immunotherapy, Birmingham, W Midlands, England
[5] NCI, Div Canc Epidemiol & Genet, Infect & Immunoepidemiol Branch, Bethesda, MD 20892 USA