Merkel cell polyomavirus DNA in persons without merkel cell carcinoma

Merkel cell polyomavirus in cutaneous swabs

To assess the usefulness of using cutaneous swabs to detect Merkel cell polyomavirus (MCPyV) DNA, we analyzed swabs from persons with Merkel cell carcinoma (MCC), others with skin diseases, and healthy volunteers. MCPyV was detected in at least 1 sample from virtually all participants. Viral loads were higher in samples from patients with MCC.

Structural evaluation of new human polyomaviruses provides clues to pathobiology

In the past three years, remarkable discoveries have added three new human polyomaviruses (KI virus (KIV), WU virus (WUV) and Merkel cell virus (MCV)) to a class that previously had only two disease-causing members (BK virus (BKV) and JC virus (JCV)) identified. Two monkey polyomaviruses, simian virus (SV)40 and B-cell lymphotropic polyomavirus (LPV) are also present in humans. KIV and WUV lack the agnoprotein coding sequence and regulatory micro (mi)RNA clusters of BKV, JCV and SV40. MCV lacks the agnoprotein sequence but generates miRNAs. KIV, WUV and MCV are all widespread in humans. Although they have distinctive tissue tropisms, all these viruses are probably acquired in childhood. Of these viruses, only MCV has thus far been strongly linked to cancer. Marshalled evidence from diverse sources implicates MCV as an etiological agent of Merkel cell carcinoma. This review compares the structural features of the new and previously known polyomaviruses, with the aim of identifying approaches to molecular pathology.

Merkel cell polyomavirus is not detected in mesotheliomas

BACKGROUND

Merkel cell polyomavirus (MCPyV) is the first polyoma virus consistently linked to the etiology of a human cancer. Serological studies indicate that the virus is commonly acquired in childhood, with seroprevalence reaching 50% or higher among young adults. The modes of MCPyV transmission are still unclear, but it has been identified in respiratory tract samples. Given its respiratory tropism, we examined whether MCPyV could be detected in mesothelioma tissue, a malignancy induced in animal models by another polyomavirus, SV40.

OBJECTIVE

To determine if MCPyV DNA can be detected in mesothelioma.

STUDY DESIGN

DNA was extracted from 45 fresh-frozen mesothelioma samples. PCR was used to detect and quantify the abundance of MCPyV DNA, and a human control gene, in duplicates of the tissues. DNA from a sequence verified MCC tumor was used as a positive control.

RESULTS

The human control gene was detected at high levels in all but three mesothelioma tissues. MCPyV DNA was detected in only one mesothelioma, and the level of viral DNA was very low.

CONCLUSIONS

These results are inconsistent with the hypothesis that MCPyV is etiologically linked to mesothelioma.

DNA from KI, WU and Merkel cell polyomaviruses is not detected in childhood central nervous system tumours or neuroblastomas

BACKGROUND

BK and JC polyomaviruses (BKV and JCV) are potentially oncogenic and have in the past inconclusively been associated with tumours of the central nervous system (CNS), while BKV has been hinted, but not confirmed to be associated with neuroblastomas. Recently three new polyomaviruses (KIPyV, WUPyV and MCPyV) were identified in humans. So far KIPyV and WUPyV have not been associated to human diseases, while MCPyV was discovered in Merkel Cell carcinomas and may have neuroepithelial cell tropism. However, all three viruses can be potentially oncogenic and this compelled us to investigate for their presence in childhood CNS and neuroblastomas.

METHODOLOGY

The presence of KI, WU and MCPyV DNA was analysed, by a joint WU and KI specific PCR (covering part of VP1) and by a MCPyV specific regular and real time quantitative PCR (covering part of Large T) in 25 CNS tumour biopsies and 31 neuroblastoma biopsies from the Karolinska University Hospital, Sweden. None of the three new human polyomaviruses were found to be associated with any of the tumours, despite the presence of PCR amplifiable DNA assayed by a S14 housekeeping gene PCR.

CONCLUSION

In this pilot study, the presence of MCPyV, KI and WU was not observed in childhood CNS tumours and neuroblastomas. Nonetheless, we suggest that additional data are warranted in tumours of the central and peripheral nervous systems and we do not exclude that other still not yet detected polyomaviruses could be present in these tumours.