Merkel cell polyomavirus (MCPyV)

virus

merkel cell polyomavirus; polyomaviridae

virus structure

small nonenveloped icosahedral capsid

viral genome

circular dsDNA

transmission

transmission not fully established; widespread infection likely via close contact

viral replication

uses host nuclear machinery for DNA replication

clinical symptoms

commonly asymptomatic; associated with aggressive merkel cell carcinoma

diagnosis

tumor biopsy and immunohistochemistry; viral testing if indicated

pathogennesis

in many tumors, viral DNA integration and altered T-antigen expression promote proliferation

treatment

surgery, radiation and cancer immunotherapy as appropriate; no specific antiviral

prevention

no vaccine; sun protection and skin monitoring help reduce overall carcinoma risk

other

UV exposure and immunosuppression are important cancer risk factors

EXAM FOCUS

DNA tumor virus linked to aggressive skin cancer