Transformation of B Lymphocytes by SV40, a small DNA tumor virus

For decades we have assessed the risk to humans by the monkey virus SV40, through studies in animal models and humans. While there is increase in the accumulation of opinions over its DNA sequence prevalence in certain human cancers, especially non-Hodgkin’s lymphoma, only few works have been addressed towards SV40 presence in human blood of healthy subject. In this work, experiment one, detected SV40 DNA sequences in 10/60 (17%) buffy coats of normal human blood donor of Aviano, Italy. In other to have insight if SV40 plays a role in lymphomagenesis, experiment two and three observed it’s in vitro interaction with normal human lymphocytes using infected and transfected purified T and B cells with SV40 virus and plasmid pSV3Neo. SV40 DNA sequences was detected with PCR analysis for 100 days post-infection (d.p.i) in both infected and transfected T and B cells respectively. Indirect immunoflourescence techniques detected VP1 protein for 50-d.p.i in infected cells and Tag protein in both infected and transfected throughout the d.p.i in culture, suggesting proper integration of SV40 into the cells. RT-PCR experiment also detected mRNA Tag for 30 and 20-d.p.i in infected T and B cells respectively. Trypan blue analysis and alamar blue assays revealed an increase of infected/transfected cells number and successively, a drastic and constant reduction in cell numbers in culture. Effective production of progeny was revealed with C.P.E and plaque assay with different titers in infected cells using CV-1 monolayer cells. Structure distortion was observed in both cell lines from early d.p.i using TEM. Presence of SV40 DNA sequence in normal blood donors suggested the human PBMCs to be a reservoir for SV40 virus. Furthermore, in this study, it has proved such as T cells and B are experimentally susceptible to infection by SV40. Further research will deepen and will focus on assessing the role of SV40 as a co-factor in the genesis of lymphoma.