Vaginal swab specimen processing methods influence performance of rapid semen detection tests: A cautionary tale

University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Contraception (Impact Factor: 2.34). 09/2010; 82(3):291-5. DOI: 10.1016/j.contraception.2010.02.022
Source: PubMed


Detection of semen biomarkers in vaginal fluid can be used to assess women's recent exposure to semen. Quantitative tests for detection of prostate-specific antigen (PSA) perform well, but are expensive and require specialized equipment. We assessed two rapid immunochromatographic strip tests for identification of semen in vaginal swabs.
We tested 581 vaginal swabs collected from 492 women. Vaginal secretions were eluted into saline, and PSA was measured using the quantitative IMx (Abbott Laboratories, Abbott Park, IL, USA) assay. Specimens were also tested using the ABAcard p30 test (Abacus Diagnostics, West Hills, CA, USA) for detection of PSA and RSID-Semen test (Independent Forensics, Hillside, IL, USA) for detection of semenogelin (Sg).
Vaginal swab extraction using saline was compatible with direct assessment of vaginal swab eluates using ABAcard for PSA detection, but not for Sg detection using RSID. The rapid PSA test detected 91% of specimens containing semen compared to 74% by the rapid Sg test.
Investigators are urged to optimize vaginal swab specimen preparation methods for performance of RSID or other tests to detect semen components other than PSA. Previously described methods for PSA testing are not uniformly applicable to other tests.

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Available from: Markus J Steiner
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    • "Biomarkers for this purpose have been based on either proteins in the seminal fluid or Ychromosome-specific genes. The area of forensics has also used various Y-specific short tandem repeats (Y-STRs) of genomic DNA to identify semen exposure [2], while clinical studies to determine semen exposure in the vagina have employed seminal proteins such as prostate-specific antigen (PSA) [3] [4] or semenogelin [5] [6]. The goals of these types of determinations are varied. "
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    ABSTRACT: Background: Developing an objective, reliable method to determine semen exposure in cervicovaginal fluids is important for accurately studying the efficacy of vaginal microbicides and contraceptives. Y-chromosome biomarkers offer better stability, sensitivity, and specificity than protein biomarkers. TSPY4 belongs to the TSPY (testis-specific protein Y-encoded) family of homologous genes on the Y-chromosome. Using a multiplex PCR amplifying TSPY4, amelogenin, and Sex-determining region in the Y chromosome (SRY), our objective was to determine whether a gene in the TSPY family was a more sensitive marker of semen exposure in cervicovaginal fluids than SRY. Study design: The multiplex polymerase chain reaction (PCR) was developed using sperm and vaginal epithelial (female) DNA. Diluted sperm DNA and mixed male/female DNA was used to determine the sensitivity of the multiplex PCR. Potential interference of TSPY4 amplification by components in cervicovaginal and seminal fluids was determined. TSPY4 and SRY amplification was also investigated in women participating in a separate IRB-approved clinical study in which cervicovaginal swab DNA was collected before semen exposure and at various time points after exposure. Results: TSPY4, SRY, and amelogenin were amplified in sperm DNA, but only amelogenin in female DNA. The limit of sperm DNA from which TSPY4 could be amplified was lower than SRY (4 pg vs 80 pg). TSPY4 could also be amplified from mixed male/female DNA. Amplification was not affected by cervicovaginal and seminal components. Using cervicovaginal swab DNA from three women before and after semen exposure, TSPY4 was detected up to 72 h post exposure while SRY detection was observed up to 24-48 h. TSPY4 was detected up to 7 days post exposure in one out of three women. Conclusions: We have demonstrated that TSPY4 is a new sensitive, and sperm-specific biomarker. The multiplex PCR incorporating this new biomarker has potential to be an objective measure for determining semen exposure in clinical trials of vaginal products such as contraceptives and HIV pre/post-exposure prophylaxis agents.
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