Director of the Ragon Institute of MGH, MIT and Harvard, Professor of Medicine at Harvard Medical School, and a Howard Hughes Medical Institute Investigator.  Dr. Walker is also an Adjunct Professor at the Nelson Mandela School of Medicine in Durban, South Africa,  where he collaborates with the Doris Duke Medical Research Institute at the University of KwaZulu-Natal. His research focuses on cellular immune responses in chronic viral infections. He also develops an intense activity for the training of the next generation of African scientists.