Developmental validation of RSID-saliva: a lateral flow immunochromatographic strip test for the forensic detection of saliva

Current methods for forensic identification of saliva generally assay for the enzymatic activity of alpha-amylase, an enzyme long associated with human saliva. Here, we describe the Rapid Stain IDentification (RSID-Saliva), a lateral flow immunochromatographic strip test that uses two antisalivary amylase monoclonal antibodies to detect the presence of salivary amylase, rather than the activity of the enzyme. We demonstrate that RSID-Saliva is accurate, reproducible, and highly sensitive for human saliva; RSID-Saliva detects less than 1 microL of saliva. The sensitivity of RSID-Saliva allows investigators to sample a fraction of a questioned stain while retaining the majority for DNA-STR analysis. We demonstrate that RSID-Saliva identifies saliva from a variety of materials (e.g., cans, bottles, envelopes, and cigarette-butts) and it does not cross-react with blood, semen, urine, or vaginal fluid. RSID-Saliva is a useful forensic test for determining which evidentiary items contain saliva and thus may yield a DNA profile.