A dot-blot-immunoassay for semen identification using a polyclonal antibody against semenogelin, a powerful seminal marker

Among various seminal plasma proteins. semenogelin (Sg), produced in the se minal vesicle, has been considered a candidate for demonstrating the presen ce of semen. Sg consists of two proteins, one 52 kDa (Sg-I) in size, and th e other a mixture of 71 and 76 kDa proteins (Sg-II). Recombinant Sg-I and S g-II proteins were obtained using a baculovirus system and then injected in to a rabbit to produce the respective antibodies [Characterization of recom binant precursor proteins of the human seminal plasma sperm motility inhibi tor synthesized in insect cells, Int. J. Mot. Med. 2 (1998) 693]. When liqu efied seminal plasma was immunoblotted with the anti-Sg-I and Sg-II antibod ies, the anti-Sg-II antibody identified a wider range of the polypeptides o riginating from Sg than did the anti-Sg-I antibody. A dot-blot-immunoassay using anti-Sg-II antibody revealed a clear immunoreactive spot even when th e semen was diluted 6400-fold. However, this assay showed that the Sg antig en was undetectable in saliva, urine, vaginal secretions, sweat, nasal secr etions and serum. To determine the stability of Sg antigenic activity, filt er paper with dried semen stains were kept at 37, 4 and 22 degreesC for 1, 6 and IS months, respectively, and the Sg antigenic activity was examined. The activity was detectable in an area not less than 0.5 cm x 0.5 cm under all of the above environmental conditions during each period. Finally, seme n was mixed with saliva or blood at various volumetric ratios, and used as a source of dried stains. The Sg antigenic activity was detectable in the s tains until the ratio of semen to saliva or blood reached 1:8. These result s suggest that Sg may be useful as a marker for semen identification. (C) 2 001 Elsevier Science Ireland Ltd. All rights reserved.