The Tan laboratory is studying human polyomaviruses: JC, BK, and the newly discovered WU, KI and MC polyomaviruses. Human polyomaviruses infect most of the general healthy population, and cause fatal diseases in the immunocompromised population. The lab has established bone marrow as a JC virus latency site.

Ongoing studies include establishing an animal model for JC virus primary infection and latency, analysis of JC and BK viral immune response in the transplantation patients, and discovery of new human polyomaviruses.