Figure 3.

Detection of circular and linear EBV DNA in cell lines by in situ lysing gel analysis. 10⁶ cells were resuspended in a loading buffer containing RNase A and loaded into a well of a 0.8% agarose-TBE lysing gel containing SDS and proteinase K. After electrophoresis the separated DNA was blotted onto nylon filters and the DNA was hybridized with ³²P labeled EBV cosmid cM-SalI-A. The upper bands on the autoradiograph constitute the episomal DNA, whereas the lower bands constitute the linear EBV-DNA which is packed into the active viruses during virus formation. EBV genoms integrated into the chromosomes of the cells do not enter the gel. Controls include B95-8 as EBV-positive and PLT-21 as EBV-negative cell lines. Episomal EBV DNA can be detected in all EBV positive cell lines. The amount of linear EBV-DNA is highly diverse or not present (IM-9, JVM-13) and does not correlate with the amount of episomal DNA.