Development of a new human polyoma virus strain (MG).

A polyoma virus isolated from the urine of a renal transplant patient has been grown on primary human foetal fibroblasts and its pattern of replication studied by thin section electron microscopy. Virus replication is characterized by the appearance of spherical, crystalline arrays in the nucleoplasm which differ from the nuclear virus crystals found in cells infected by the human polyoma virus prototypes JC and BK. A serological study has substantiated differences between the prototypes and the MG isolate. The affinity of MG and other polyoma viruses for the cell membrane suggests a possible basis for the demyelinating effect seen in cases of polyoma-associated progressive multifocal leucoencephalopathy.