Detection of HHV-6 DNA by Southern blot analysis. Total cellular DNAs were digested with BamHI, subjected to electrophoresis through a 0.75% agarose gel, transferred onto a nylon-membrane filter, and hybridized with the ³²P-labeled BamHI fragment of HHV-6 DNA. A hybridizaion band at 6.9 kb is seen in lanes 1 and 3. Positions of size markers are shown on the left. Lane 1, HHV-6–infected MT-4 cells; lane 2, Akata cells; lane 3, Katata cells.