EBV and KSHV DNA in plasma were detected as previously described [27] . Viral DNA levels were determined by real-time, quantitative PCR using K8 primers for KSHV and BamHI-W primers for EBV. Controls were constructed by the addition of viral DNA to serum from healthy donors. Standard curves (with duplicate serial 10-fold dilutions of plasmid DNA that included a target sequence from 10 5 to 10 copies) were run in parallel with each analysis.