Detection of EBV Infection at the Single-Cell Level: Precise Quantitation of Virus-Infected Cells In Vivo

The polymerase chain reaction (PCR) has become a powerful tool in the world of molecular biology (1 ). Using specific oligonucleotides complimentary to a known sequence of DNA in conjunction with Taq DNA polymerase, it is possible to synthesize billions of copies of that DNA from only one starting molecule. The benefits of this technique are numerous. This methodology is especially useful in the study of Epstein-Barr virus (EBV). EBV-infected cells in the peripheral blood of healthy donors are present at very low numbers in the order of 1–50 per 10⁶ B cells (2 ). Direct detection of these infected cells is essentially impossible without PCR. Therefore, the required PCR reaction must detect 1 EBV-infected cell in a background of 10⁶ uninfected cells to be able precisely and reliably to quantitate the number of infected cells in a given donor.