Applicability of ELISA detection of statherin for forensic identification of saliva

Statherin is a low molecular-weight phosphoprotein secreted from the parotid gland. Statherin mRNA was previously reported to be a useful marker for mRNA-based saliva identification. In this study, applicability of ELISA detection of statherin for forensic identification of saliva was investigated. The specificity and sensitivity of ELISA for detection of statherin were compared with those of ELISA for α-amylase and the Phadebas® amylase test. Statherin was specifically detected in saliva but not in other body fluids. In addition, statherin was successfully detected in aged saliva stains, mixed body fluids-saliva stains, and simulated casework samples. On the other hand, although ELISA for α-amylase showed higher sensitivity than ELISA for statherin, it was not specific enough to identify saliva. The Phadebas® amylase test also showed positive results in other body fluids that are known to have α-amylase activity; however, it is easy to use for screening forensic casework samples. In conclusion, ELISA for detection of statherin developed in this study could be an effective tool for the forensic identification of saliva because of its specificity for saliva among other body fluids. Forensic casework samples should be tested by ELISA detection or mRNA-based analysis for statherin, depending on the condition of the sample, to supplement presumptive tests for α-amylase, such as the Phadebas® amylase test.