Seroprevalence of Four Polyomaviruses Linked to Dermatological Diseases: New Findings and a Comprehensive Analysis

Prevalence and in vitro study of human polyomavirus 9

Little is known about human polyomavirus 9 (HPyV9). The mode of transmission and the site of replication are unknown, and seroprevalence data have been published with a wide range. A total of 1038 serum samples from individuals aged 0.7-93 years were used for seroprevalence study. We observed that seropositivity increased with age among children and young adults, and a 36.2% adult seroprevalence was detected. The prevalence was examined in samples from the respiratory tract: cancerous and non-cancerous lung tissues, tonsils, adenoids, throat swabs, middle ear discharge and nasopharyngeal samples collected from children and adults. HPyV9 was detected in 5.2% of nasopharyngeal samples and 1% of tonsils. Upon a viral infection, the interaction of viral promoters and cellular factors may determine whether a virus productively replicates in a cell. The early and late promoter activity of HPyV9 and the effect of the large T antigen (LTAg) on it was investigated in respiratory, kidney, endothelial and colon cell lines, fibroblast and primary airway epithelial cells. The highest promoter activity was measured in A549 lung cell line. LTAg expression significantly increased the late promoter activity. Based on our results, the respiratory cells may be suitable for HPyV9 replication.

DNA and seroprevalence study of MW and STL polyomaviruses

The clinical importance and the pathogenesis of the MW and STL polyomaviruses (PyVs) remain unclear. Our aim was to study the seroprevalence of MWPyV and STLPyV, and to examine the prevalence of viral DNA in respiratory samples and secondary lymphoid tissues. In total, 618 serum samples (0.8-90 years) were analyzed for seroprevalence. For the DNA prevalence study, 146 patients (2.5-37.5 years) were sampled for adenoids (n = 100), tonsils (n = 100), throat swabs (n = 146), and middle ear discharge (n = 15) in study Group 1. In Group 2, we analyzed 1130 nasopharyngeal samples from patients (0.8-92 years) tested for SARS-CoV-2 infection. The adult seropositivity was 54% for MWPyV, and 81.2% for STLPyV. Both seroprevalence rates increased with age; however, the majority of STLPyV primary infections appeared to occur in children. MWPyV was detected in 2.7%-4.9% of respiratory samples, and in a middle ear discharge. STLPyV DNA prevalence was 1.4%-3.4% in swab samples, and it was detected in an adenoid and in a middle ear discharge. The prevalence of both viruses was significantly higher in the children. Noncoding control regions of both viruses and the complete genomes of STLPyV were sequenced. MWPyV and STLPyV are widespread viruses, and respiratory transmission may be possible.

Trichodysplasia Spinulosa

Trichodysplasia spinulosa (TS) is a unique, rare clinical and histological dermatologic entity described mainly in a setting of immunosuppression. It is caused by a novel human polymoavirus, TS-associated polyomavirus. Reduction of immunosuppression and/or anti-viral therapy is the main therapeutic strategies used to treat such cases. We report a biopsy-proven case of TS in a male renal transplant patient who presented to a dermatology outpatient clinic in Montreal, Canada, in 2015. He was managed with valgancyclovir with no obvious response. Subsequently, a trial of topical imiquimod was commenced. Awareness of TS can prompt early diagnosis and management to prevent possible complications.

Epidemiology of Merkel Cell Polyomavirus Infection and Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) is a ubiquitous virus replicating in human dermal fibroblasts. MCPyV DNA can be detected on healthy skin in 67−90% of various body sites, and intact virions are regularly shed from the skin. Infection occurs early in life, and seropositivity increases from 37 to 42% in 1- to 6-year-olds to 92% in adults. Merkel cell carcinoma (MCC) is a rare but very aggressive neuroendocrine tumor of the skin. It develops mainly on sun-exposed areas as a fast-growing, reddish nodule. Two MCC entities exist: about 80% of MCC are MCPyV-associated. Tumorigenesis is driven by viral integration into the host genome and MCPyV oncogene expression. In MCPyV-negative MCC, UV radiation causes extensive DNA damage leading to the deregulation of the cell cycle. In recent decades, MCC incidence rates have increased worldwide, e.g., in the United States, from 0.15 in 1986 to 0.7/100,000 in 2016. Risk factors for the development of MCC include male sex, older age (>75 years), fair skin, intense UV exposure, and immunosuppression. Projections suggest that due to aging populations, an increase in immunosuppressed patients, and enhanced UV exposure, MCC incidence rates will continue to rise. Early diagnosis and prompt treatment are crucial to reducing high MCC morbidity and mortality.