JC virus (JCV), the agent of progressive multifocal leucoencephalopathy (PML), exerts an oncogenic effect in several laboratory animal models. Moreover, JCV genomic
DNA and early
viral protein T-antigen have been detected in various types of human central nervous system (
CNS) neoplasms. To further explore this association we have studied
paraffin-embedded brain biopsy tissue from 60
neoplasms (55
gliomas and five
medulloblastomas) and 15 reactive
gliosis cases for the presence of JCV DNA sequences and
proteins. Four post mortem cases of HIV-associated PML were used as positive controls. Samples were assessed by polymerase chain reaction (PCR) amplification of early (
large T antigen) and late (virion
protein 3) sequences and immunohistochemistry (IHC) with both PAb 2024 and anti-SV40
large T antigen monoclonal antibodies. Five cases (three
neoplasms and two reactive
gliosis instances) showed low
viral DNA levels when PCR-tested for VP3 or large T, while no case was immunoreactive for any of the two
antibodies used. The four PML cases yielded positive results with both PCR and IHC. Additionally, IHC with both
antibodies was applied to a tissue micro-array including 109 CNS tumours and 21 reactive
gliosis samples. No immunoreactivity was detected in any of these tissue micro-array samples. The rarity of JCV DNA sequences and early
proteins in our brain tumours enriches the controversy over the role of JCV in human neurooncogenesis, whose clarification is in need of further molecular and epidemiologic studies.