Comparison of JC and BK human papovaviruses with simian virus 40: DNA homology studies.

Studies were performed to ascertain the relationship of human papovavirus JC to BK virus and to simian virus 40 (SV40) by further restriction endonuclease analysis and by DNA-DNA competition hybridization on membrane filters. Form I DNA extracted from two new isolates from cases of progressive multifocal leukoencephalopathy of human papovaviruses that were JC-like in their antigenic properties were found to yield restriction endonuclease fragmentation patterns similar to those of prototypic JC virus DNA and different from those of BK or SV40. Form I DNA preparations of JC and BK viruses were found to be related to each other and to SV40 DNA to a similar extent, with JC and BK virus DNAs containing sequences homologous to both early and late regions of the SV40 genome. The relatedness in each comparison was less than 50%, and heterologous hybrids between either JC or BK and SV40 DNAs were found to be less stable than homologous SV40-SV40 hybrids in high concentrations of formamide, suggesting substantial mismatch within homologous regions, to the extent of 15 to 30%. The new JC-like isolates were also studied in competition hybridization reactions with SV40 DNA and yielded results similar to those obtained with JC virus.