Characterization of a Monoclonal Antibody to a Conserved Epitope on Human Seminal Vesicle-Specific Peptides: A Novel Probe/Marker System for Semen Identification1

Abstract

A novel sperm-coating antigen from the human seminal vesicles was discovered. We identified a monoclonal antibody MHS-5, recognizing an epitope with characteristics of a forensic semen marker: conservation in all vasectomized or normal semen samples tested (421); absence in all human tissues or biological fluids other than semen; and immunolocalization on the surface of ejaculated sperm. Western blots of ejaculates allowed to liquefy for 5 min demonstrated the MHS-5 epitope to be located on peptides of a wide range of molecular masses from 69 to 8 kDa. After 15 h of semen liquefaction, immunoreaction peptides of higher molecular mass were undetectable in semen, while peptides of lower molecular mass from 8 to 21 kDa retained antigenicity. Three peptides of 10, 11.9, and 13.7 kDa were the most immunoreactive species in semen liquified for 15 h. Using the MHS-5 monoclonal, an enzyme-linked immunosorbent assay (ELISA) was developed sensitive to 1 ng of seminal protein. This assay showed that the MHS-5 antigen was undetectable in semen of common domestic animals and monkeys but was present in chimpanzee, gorilla, and orangutan semen. ELISA of homogenates from human organs and reproductive tissues demonstrated the antigen only in samples of seminal vesicles. Epididymal sperm obtained at vasovasostomy lacked the MHS-5 epitope, a fact that, together with immunolocalization on ejaculated sperm, demonstrated that the MHS-5 antigen functions as a "sperm-coating antigen." The MHS-5 monoclonal detected semen in sexual-assault evidence obtained six months previously and in mixtures of semen with vaginal or cervical fluid. Assay systems employing the MHS-5 monoclonal may be useful for identification of semen in sexual-assault casework. The MHS-5 epitope resides on novel seminal vesicle-specific peptides whose functions, aside from sperm coating, are uncharacterized.

Molecular cloning of epididymal and seminal vesicular transcripts encoding a semenogelin-related protein.

“…A similar immunological crossreactivity has also been seen by a monoclonal antibody. Analysis of freshly ejaculated human semen with the monoclonal antibody MHS-5 identified a common epitope of the three major proteins of 58, 69, and 71 kDa (26,27). Similar to the properties described for Sg, the three MHS-5 reacting proteins, commonly referred to as the seminal vesiclespecific antigen (SVSA), are degraded during semen liquefaction by PSA (27,28) and distributed on the surface of ejaculated spermatozoa (29).…”

Evaluation of MHS-5 in detecting seminal fluid in vaginal swabs

“…Of these, 3 were positive for ACR According to the manufacturer, the Phosphatesmo-KM test does not react with endogenous vaginal phosphatase [13]. A positive Phosphatesmo should thus be interpreted as a sign of the presence of seminal fluid, since MHS-5 does not react with vaginal fluid [11]. Conversely, it is indeed possible that a positive SVSA test in the absence of the other markers indicates the presence of semen, as in 4 of our cases (Table 1, Fig.…”

“…5 (MHS-5) was first described by Herr et al 1986 [11]. This antibody is directed against the SVSA (seminal vesicle- [7,11]. Therefore, SVSA belongs to the group of semen markers that are also positive in cases of azoospermic or aspermic semen.…”

“…It has since been found [14] that SVSA is a substrate of p30 [17]. In the light of experimental data there can be no doubt that SVSA is human and organ specific; only primate semen samples showed cross reactions [11]. The use of SVSA proved to be feasible for the forensic detection of seminal fluid [20].…”

Semenogelin I: a coagulum forming, multifunctional seminal vesicle protein

“…On the other hand, the epitope for the MHS-5 monoclonal antibody appears to map to a more centrally located section of Sg I [37]. This antibody was originally raised against whole spermatozoa but found to recognize a sperm-coating antigen originating from the seminal vesicles [38]. The antigen recognized by MHS-5 antibody is referred to as seminal vesicle-specific antigen (SVSA) and is present on a range of polypeptides.…”