Dr. Malley’s research is focused on innate and acquired immunity to Streptococcus pneumoniae. His work on Toll-like receptors led to the discovery that TLR4 mediates recognition and resistance to pneumococcal colonization and disease. He was the first to discover the existence of CD4+ T cell-dependent, antibody-independent mechanisms of resistance to pneumococcal infection. Overall, his body of work has wide-ranging implications for our understanding pneumococcal pathogenesis and the development of novel vaccine candidates.