PCR approach based on SYBR Green chemistry, allowing simultaneous detection of multiple targets, was chosen to be applied for the array performance. Virus-specific primer sets targeting at least three different genomic sites for each viral pathogen were designed for the real-time PCR array. We used the ''Insignia'' program, a bioinformatics tool that helps to choose a specific DNA or RNA ''signature'' for different bacteria and viral pathogens that are included in the pre-built ''Insignia'' database [13] . Sequences of the highly conserved regions, such as coding viral polymerase or structural proteins were selected to design the candidate primers. In addition, we performed nucleotide sequence alignments (NSA) of the complete viral genomes and of the most conserved genome areas for different subtypes/genotypes or different isolates of all targeted viruses. Some previously published primers designed for PCR detection of the target viruses were also adapted and evaluated. Overall, a total of 120 primers were initially designed using specific criteria for the current real-time PCR array (see Materials and Methods) to cover the eight targeted viruses: HIV-1, HIV-2, HBV, HCV, HTLV-1, HTLV -2, WNV, and VACV. The primers were designed and tested for their effectiveness and specificity of amplifying the respective target under uniform PCR conditions (using the same annealing temperature for all primers).