The five lanes on the right, labeled “B 95-8 Cell Line”, represent the electrophoresis of DNA from this cell line, which is used as a control to determine the sensitivity of the semiquantitative EBV PCR assay. DNA from a known number of cells is run in each lane, and the lowest dilution at which a band is still visible corresponds to 10 cells. Because each B 95-8 cell has two copies of the EBV genome, the sensitivity of this assay is 20 copies EBV DNA. The first five lanes represent different amounts of DNA per lane from a patient. The last visible band corresponds to the 0.05-ng dilution. The number of copies of EBV genome per microgram DNA (in this case 400,000 copies/μg DNA) is calculated by dividing the sensitivity of the assay (20 copies/μg DNA) by the concentration of DNA for the last visible band (0.05 × 10−3 μg).
