The intent of this solicitation is to leverage prior government and industry investments which have examined quality control processes for array manufacturing, array content, sample handling, assay chemistries and data analysis algorithms to optimize the technology and have enabled the association of blood samples with disease states. Proposals should provide experimental designs that answer key questions to understanding the utility of peptide array technology, which include: 1) the ability to differentiate diseases with high specificity, 2) the ability to capture a disease during early symptomatic stages to support clinical diagnosis, 3) the ability to differentiate acute vs chronic vs previous exposure vs vaccinated individuals, and 4) the ability to obtain reliable and reproducible results by leveraging a defined quality control process during manufacturing and accommodating sample variability.