Analysis of Detection of Mixed Semen Stains with Different Immunological Test Methods and Case Applications

Abstract

Objective To perform the separation and confirmation of mixed semen stains with immunological test method, and find a more effective method for the detection of mixed semen stains. Methods The semens of three volunteers were mixed. The mixed semen stains were processed and tested with prostate-specific antigen （PSA） colloidal gold immunoassay strip method, immunomagnetic beads method and laser capture microdissection, respectively. Statistics of the results of STR were gathered and compared with those of a single semen stain. Results After PSA colloidal gold immunoassay strip method testing, the samples showed a purplish red line in the test area and the control area. The results obtained with the immunomagnetic beads method showed a more complete and effective short tandem repeat （STR） sequence. The mixed semen stains were processed with laser capture microdissection and low volume amplified. The results were summarized and superimposed to obtain a complete single typing, which matched the single semen stain typing, with a typing success rate of 84.00%. Single suspect Y-STR typing was obtained with the application of the method above in actual cases, which provided evidence basis for rapid solving of the case. Conclusion The combination of PSA colloidal gold immunoassay strip method, immunomagnetic beads method and laser capture microdissection can be used to separate and confirm the mixed semen stains.

Keywords: forensic genetics; short tandem repeat; Y chromosome; mixed seminal stain; immunocolloidal gold; immunomagnetic bead; laser capture microdissection.