Comparing markers of viral exposure in Saliva and Blood from SpaceX Donors using PepSeq
PepSeq is a highly multiplexed assay that utilizes a standard peptide library to determine the presence of viral antibodies within a sample. Antibody binding profiles have previously been obtained using both serum and reconstituted dried blood spots (DBS); however, there are many individuals who are unable to provide these sample types due to age and/or health complications. Optimizing the PepSeq protocol to include saliva as a sample type will allow for a less invasive collection procedure and expand the capability of the PepSeq platform. Preliminary data from enzyme-linked immunosorbent assays (ELISA) provided evidence that saliva contains lower concentrations of IgG and IgA immunoglobulin isotypes than do blood or plasma samples. Based on these results, we tested varying volumes of saliva against our library in an effort to identify effective sample volume:concentration ratios. To validate saliva as a sample type, the abundance and functionality of the antibodies in each sample were measured and compared to those from a matched dried blood spot. Following the initial analysis, we observed that the presence of saliva hinders binding between the peptide library and the control serum. To ensure the success of protocol optimization, our next priorities will be to identify which inhibitory factors within saliva are impeding the overall binding reaction, as well as to concentrate and purify saliva samples.
