Joe Trapani is an immunologist whose research focuses on how cells of the immune system kill harmful cells - those infected with a virus or undergoing cancerous transformation. Trapani discovered several diverse toxins that mediate cell death, and determined how they function, individually and in synergy. His studies also address structure/function relationships for the pore-forming protein perforin and the signalling pathways activated by the ‘granzyme’ proteases to induce target cell apoptosis. Trapani also elucidated how defects in cell death pathways impinge on human health/disease, and how immune ‘killer cells’ can be harnessed as therapies for cancer, viral and auto-immune diseases.