Dr. Hao Shen has a long-standing interest in basic questions related to generation of effective immune responses, mechanisms of protective immunity, and the establishment of long-term immunological memory. For these basic studies, he has used two well-characterized murine models of infection with lymphocytic choriomeningitis virus (LCMV) and Listeria monocytogenes. More recently, his group is interested in viral/bacterial co-infections, which occur frequently in clinics and often result in more severe disease than infection by an individual pathogen. A striking example of this is the high mortality caused by secondary bacterial pneumonia following flu infection.