抄録
Since 1971 several new papovaviruses have been found and isolated from humans, especially from the brains of patients suffering from progressive multifocal leucoencephalopathy(PML). These human papovaviruses (such as JC, BK, SV40-PML viruses), though antigenically dissimilar to papilloma or polyoma viruses, bear certain physicochemical similarities to simian virus 40 (SV40). The oncogenic potential in hamster of these human papovaviruses (JC, BK) has been reported, raising a suspicion that some human brain tumors may have a viral etiology. As virus-induced animal tumors display virus-specific common antigen(s) irrespective of tumor histology or site, our attention has been directed to the immunocytochemical screening of human brain tumors for the presence or absence of SV40-related T(tumor) antigen, because this protein is known to share common antigenic activity with T antigen(s) induced by human papovaviruses.
At the time of writing this paper, 39 human brain tumors have been screened for SV40-related T antigen in vivo by immunoperoxidase technique using hamster anti-SV40 T antibody as well as normal hamster serum as a control. Two (one ependymoma, one choroid plexus papilloma) out of 39 cases examined displayed markedly positive staining in the nuclei of tumor cells with anti-SV40 T antiserum, but neither with normal hamster serum nor with anti-SV40 V (nucleocapsid antigen) antibody. An independent complement fixation assay of the nuclear extracts from one of the two positive tumors also confirmed the presence of the antigen which specifically reacted with hamster anti-SV40 T antiserum.
There have been few systematic searches for papovavirus-related antigens in human neoplasms. However, in 1975 SV40-related T and U antigens have been observed in three cases of human meningioma cells by an immunofluorescence test. Since human cells are semipermissive for papovaviruses, these and our findings strongly suggest a viral etiology for some human brain tumors.
