Serological Evidence of an Early Seroconversion to Simian Virus 40 in Healthy Children and Adolescents

Angelo Taronna,Elisa Mazzoni,Roberto Marci,Ilaria Bononi,Massimo Bovenzi,Silvia Pietrobon,Giovanni Rezza,Caterina Borgna-Pignatti,Fernanda Martini,Ferruccio Casali,Manola Comar,Mauro Tognon,Alfredo Corallini,Giuseppe Barbanti-Brodano,Giovanni Guerra,Caterina Palmonari,Eugene Oliver Major

doi:10.1371/journal.pone.0061182

Abstract

At present Simian virus 40 (SV40) infection in humans appears to be transmitted independently from early contaminated vaccines. In order to test the spread of SV40 infection in children, an immunologic assay employing specific SV40 synthetic peptides corresponding to its viral protein (VP) antigens was employed to estimate the seroprevalence of this polyomavirus in Italian infants and adolescents. Serum samples from 328 children and adolescents, up to 17 years, were investigated. Serum antibodies against SV40 VPs were detected by indirect enzyme-linked immunosorbent assays. The seroprevalence of this polyomavirus was calculated after stratifying the subjects by age. Anti-viral capsid protein 1-2-3 SV40 IgG antibodies were detected in 16% of the study participants. The prevalence of antibodies against SV40 VPs tended to increase with age in children, up to 10 year old (21%). Then, in the cohort of individuals aged 11–17 years, the prevalence decreased (16%). A higher prevalence rate (23%) of SV40 VP antibodies was detected in the cohorts of 1–3 year and 7–10 year old children, than in children and adolescents of the other age groups. This age corresponds to children starting nursery and primary school, respectively, in Italy. IgM antibodies against SV40 VP mimotopes were detected in 6–8 month old children suggesting that SV40 seroconversion can occur early in life. SV40 VP antibodies are present at low prevalence in Italian children (16%), suggesting that SV40 infection, although acquired early in life, probably through different routes, is not widespread. The low SV40 seroprevalence suggests that SV40 is less transmissible than other common polyomaviruses, such as BKV and JCV. Alternatively, our immunologic data could be due to another, as yet undiscovered, human polyomavirus closely related to SV40.

Highlights

Simian virus 40 (SV40) is a non-enveloped small DNA virus with a genome of approximately 5.2 kb in size
Our results indicate a low homology, similar to those already reported for the BK virus (BKV) and JC virus (JCV) prototypes and other polyomaviruses [3]
Serum samples which reacted with the SV40 VP1 B mimotope reached, in children aged up to one year, the prevalence of 13% for SV40 antibodies in the IgG class, increased with age, reaching 25% in the 1–10 ys age range

Summary

Introduction

Simian virus 40 (SV40) is a non-enveloped small DNA virus with a genome of approximately 5.2 kb in size. SV40 was recognized in the 1960 as contaminant of both inactivated (Salk) and live (Sabin) anti-poliomyelitis vaccines. SV40 was experimentally characterized as a transforming and oncogenic virus [1,2]. SV40 late region contains three main genes encoding for three structural polypeptides, the viral capsid proteins 1, 2 and 3 (VP 1-2-3). VP 2 and 3 genes partially overlap [3]. Several studies, carried out mainly by PCR techniques, suggest that SV40 is contagiously transmitted in humans by horizontal infection, independently of the administration of SV40-contaminated vaccines [1,2]. The circulation of SV40 in human populations before the administration of contaminated vaccines cannot be excluded

Methods

Results

Conclusion