Specific Detection of Serum Antibodies against BKPyV, A Small DNA Tumour Virus, in Patients Affected by Choroidal Nevi

Abstract

Ocular or choroidal nevus (CN) is a rare benign neoplastic lesion of the eye. The cause of CN onset/progression, which arises from the transformation of ocular melanocytes, is not known. A fraction of CN patients may develop uveal melanoma. The objective of this study was to investigate the association between CN and BK polyomavirus (BKPyV), a small DNA tumor virus. Serum IgG antibodies which react with BKPyV antigens were analyzed. An indirect E.L.I.S.A. using synthetic peptides that mimic BKPyV antigens was employed. Serum antibodies against BKPyV were also investigated by haemagglutination inhibition (HAI) assay. Sera were from CN patients and healthy subject (HS) were the control. A statistically significant higher prevalence of antibodies against BKPyV capsid protein antigens in serum samples from CN patients was detected, compared to HS, using two independent techniques, indirect E.L.I.S.A. and HAI (87.3% CN vs. 62.1% HS and 91.5% CN vs. 64.4% HS, respectively; p < 0.005). Our data suggest an association exists between CN and BKPyV indicating that this small DNA tumor virus could be responsible in the onset of this benign neoplastic lesion affecting eye melanocytes. This investigation reports the association between choroidal nevi and BKPyV infection for the first time. These data are innovative in this field and may represent a starting point for further investigation into the putative role of BKPyV in CN onset/progression.

Keywords: BKPyV; antibody; choroidal nevus; prevalence; serum; titer.

Figure 1

Serologic profile of serum antibody reactivity to BKPyV mimotopes VP1 L (A) and VP1 M (B) and VP1 L+M (C). Immunologic data are from CN and HS serum samples. Results are presented as values of optical density (OD) readings at λ 405 nm of serum samples diluted at 1:20, detected by the indirect enzyme-linked immunosorbent assay. In scatter dot plotting, each plot represents the dispersion of OD values to a mean level indicated by the line inside the scatter with SEM for each group of patients/subjects analyzed. (A) The mean OD for VP1 L in CN and HS does not differ statistically, while (B) the mean OD of sera (VP1 M ± Std Error) in CN (0.326 ± 0.008) is higher than that detected in HS (0.417 ± 0.021). (C) The mean OD of sera (VP1 B+C ± Std Error) in CN (0.329 ± 0.015) is lower than that detected in HS (0.372 ± 0.012). Statistical analyses were performed using t-test.