Schematic drawing of the multivirus-chip that possesses multiple functions. The multi-virus array used in the study conducted by Ghedin, et al. contains more than 250 DNA spots derived from PCR amplification of ORFs from eight human pathogenic viruses. These viruses include HIV-1, HTLV-1, HTLV-2, EBV, HHV-6A, HHV-6B, KSHV, and HCV. Depending on how the DNA targets are prepared, the multivirus-chip can be simultaneously used to detect viral genomic sequences, profile viral gene expression patterns, and investigate the relationship between cellular chromatin structure and viral gene transcription. Therefore, this multi-purpose DNA array is functionally versatile and would be very useful in both clinical diagnoses and biomedical research.