The research study conducted at FDA using previously frozen blood samples was reviewed by Department of Health and Human Services, Food and Drug Administration, Research Involving Human Subjects Committee (RISHC Protocol #10-008B entitled ''Detection of Infectious Agents in Previously frozen blood Samples from Patients with Various Illnesses and Healthy Blood Donors''). The 17 clinical plasma samples positive for HBV, HCV or HIV-1 used in this study were existing clinical diagnostic samples kept in NIH Blood Bank. Information of these left over samples had been recorded in such a manner that subjects can not be identified, directly or through identifiers. The written informed consent from the participants was waived under 45 CFR 46.101 (b) (4) . The six plasma samples positive for HIV-1 were estimated to contain 50 to ,90,000 genome copy numbers per ml; six plasma samples positive for HCV were estimated to contain 780 to ,123,000 genome copy number/ml and five plasma samples positive for HBV were estimated to contain ,150 to 16,000 copy number/ml. The copy numbers of viruses in these samples were provided by the NIH Blood Bank. No information about the subtypes or genotypes of these viruses was available. The amount of each clinical sample was sufficient to be tested only once by the PCR array in the study. All positive PCR products obtained in the testing using the PCR array were confirmed for validity by sequencing in the Facility for Biotechnology Resources of FDA/ CBER.