Garvin Alex M, Fischer Andrea, Schnee-Griese Jutta, Jelinski Andrea, Bottinelli Michel, Soldati Gianni, Tubio Monica, Castella Vincent, Monney Nathalie, Malik Naseem, Madrid Michelle
Confarma France SARL, Zone Industrielle Canal d'Alsace, Hombourg, 68490, France.
Investig Genet. 2012 Dec 4;3(1):25. doi: 10.1186/2041-2223-3-25.
Profiling sperm DNA present on vaginal swabs taken from rape victims often contributes to identifying and incarcerating rapists. Large amounts of the victim's epithelial cells contaminate the sperm present on swabs, however, and complicate this process. The standard method for obtaining relatively pure sperm DNA from a vaginal swab is to digest the epithelial cells with Proteinase K in order to solubilize the victim's DNA, and to then physically separate the soluble DNA from the intact sperm by pelleting the sperm, removing the victim's fraction, and repeatedly washing the sperm pellet. An alternative approach that does not require washing steps is to digest with Proteinase K, pellet the sperm, remove the victim's fraction, and then digest the residual victim's DNA with a nuclease.
The nuclease approach has been commercialized in a product, the Erase Sperm Isolation Kit (PTC Labs, Columbia, MO, USA), and five crime laboratories have tested it on semen-spiked female buccal swabs in a direct comparison with their standard methods. Comparisons have also been performed on timed post-coital vaginal swabs and evidence collected from sexual assault cases.
For the semen-spiked buccal swabs, Erase outperformed the standard methods in all five laboratories and in most cases was able to provide a clean male profile from buccal swabs spiked with only 1,500 sperm. The vaginal swabs taken after consensual sex and the evidence collected from rape victims showed a similar pattern of Erase providing superior profiles.
In all samples tested, STR profiles of the male DNA fractions obtained with Erase were as good as or better than those obtained using the standard methods.
对从强奸受害者阴道拭子中提取的精子DNA进行分析，通常有助于识别和监禁强奸犯。然而，大量受害者的上皮细胞会污染拭子上的精子，使这一过程变得复杂。从阴道拭子中获取相对纯净精子DNA的标准方法是用蛋白酶K消化上皮细胞，以溶解受害者的DNA，然后通过将精子沉淀、去除受害者的DNA部分，并反复洗涤精子沉淀，将可溶性DNA与完整的精子物理分离。另一种不需要洗涤步骤的方法是用蛋白酶K消化，沉淀精子，去除受害者的DNA部分，然后用核酸酶消化残留的受害者DNA。
核酸酶法已在一种产品中商业化，即Erase精子分离试剂盒（美国密苏里州哥伦比亚市PTC实验室），五个犯罪实验室已在精液加样的女性口腔拭子上对其进行了测试，并与他们的标准方法进行了直接比较。还对性交后定时阴道拭子以及从性侵犯案件中收集的证据进行了比较。
对于精液加样的口腔拭子，Erase在所有五个实验室中均优于标准方法，在大多数情况下，仅用1500个精子加样的口腔拭子就能获得清晰的男性图谱。自愿性交后采集的阴道拭子以及从强奸受害者那里收集的证据显示出类似的模式，即Erase能提供更优质的图谱。
在所有测试样本中，用Erase获得的男性DNA部分的STR图谱与使用标准方法获得的图谱一样好或更好。
