Abstract
We produced capsids of Merkel cell polyomavirus (MCPyV) in a baculovirus expression system and developed a virus-like particle (VLP) enzyme-linked immunosorbent assay (ELISA). To determine age-specific seroprevalence, serum samples were collected from 947 individuals attending hospital outpatient clinics and ranging in age from 1 to 93 years. To evaluate the association between exposure to MCPyV and Merkel cell cancer (MCC), plasma samples were obtained from 33 MCC patients and 37 controls. MCPyV seroprevalence was 45% in children under 10 years of age, increased to 60% in the next decade of life, and peaked at 81% among those 60 to 69 years of age. Levels of MCPyV capsid antibodies were positively correlated with age (P = 0.007). Virus specificity of MCPyV seroreactivity was supported by competitive inhibition of reactivity by MCPyV VLPs and not by BK polyomavirus (BKPyV) VLPs. MCPyV seroprevalence was greater among MCC patients (91%) than controls (68%; age-adjusted P value, 0.32); the mean level of MCPyV antibodies was also greater (P = 0.04). The age-specific seroprevalence of MCPyV shares with previously known polyomaviruses, BKPyV and JC polyomavirus (JCPyV), evidence of widespread exposure in human populations beginning early in life. MCPyV age-specific seroprevalence also has unique features. Seroprevalence among children is higher than that of JCPyV but lower than that of BKPyV. Among older adults, MCPyV seroprevalence remains high, while that of BKPyV declines and that of JCPyV continues to rise. In agreement with results from other studies, we found an association between MCPyV seropositivity and MCC, and higher levels of serum MCPyV capsid antibodies in MCC patients than in controls.