Distribution of the number of probes per species in the GreeneChip. Since the design of the array is based on viral strains, we design many strain specific probes in human viruses (e.g. HIV, Influenza). Indeed, Genbank often contains multiple entries of fully sequenced genomes for human viruses strains allowing for straightforward calculation of conservation and specificity. In contrast, some other vertebrate viruses may have as little as a single Gnebank entry and perhaps an incomplete genome. In the latter case, probes were designed using principles of phylogenetic protein domain conservation .