Predominant Merkel Cell Polyomavirus DNA Detection in Essential Thrombocythemia within Myeloproliferative Neoplasms

Acute thrombocythemic myeloproliferative disease in mice has been reported upon introduction of Middle T gene expression of mouse polyomavirus. Merkel cell polyomavirus (MCPyV) is an oncogenic human polyomavirus that accounts for approximately 80% of all Merkel cell carcinomas. In this study, we assessed the presence of MCPyV DNA in fresh bone marrow (BM) aspirates from patients with myeloproliferative neoplasms (MPNs) using MCPyV-specific DNA polymerase chain reaction (PCR). MCPyV DNA prevalence was significantly higher in 78 BM samples from MPN patients (17.9%, 14/78) than in 66 BM controls undergoing femoral head replacement surgery (3%, 2/66; Fisher's exact test, p = 0.0063; OR = 7.95% confidence interval (CI) = 1.53-32.06). Notably, positivity was predominant in essential thrombocythemia (ET; 11/14). MCPyV mRNA was detected in MCPyV-DNA-positive samples, indicating low-level viral transcription. Interestingly, MCPyV positivity was significantly correlated with female sex but not with age or specific MPN genetic mutations, except for myeloproliferative leukemia virus oncogene (MPL) mutations. These findings suggest a potential association between MCPyV and MPNs, particularly ET, and support further investigation into the role of human polyomavirus in megakaryocytic lineage biology.