Screening of an Antigen Target for Immunocontraceptives from Cross-Reactive Antigens between Human Sperm andUreaplasma urealyticum

Abstract

Epidemiologic studies indicated that some infertile men who were infected with Ureaplasma urealyticum displayed positive antisperm antibodies in their serum and/or semen. The purpose of this study was to investigate the possible mechanism of antisperm antibodies production after infection with U. urealyticum and to analyze the relationship between U. urealyticum and infertility. The existence of cross-reactive antigens (61, 50, and 25 kDa) between U. urealyticum and human sperm membrane proteins was confirmed. Among the cross-reactive antigens, the urease complex component UreG of U. urealyticum was determined. By searching the Swiss-Prot protein database, a pentapeptide identity (IERLT) between UreG and human nuclear autoantigenic sperm protein (NASP) was found. Furthermore, using Western blot analysis and enzyme-linked immunosorbent assay, the cross-reaction between the NASP and UreG was verified. Both anti-rUreG antibody and the antiserum against the synthetic peptide NASP393-408 containing the pentapeptide inhibited mouse sperm egg binding and fusion. After immunization by rUreG or the synthetic peptide, 81.2 and 75% female mice became sterile, respectively. The effect on fertility in mice immunized with the synthetic peptide was reversible. These findings proved for the first time that it was feasible to screen antigens for immunocontraceptives from cross-reactive antigens between sperm and microorganisms which induce infertility.Ureaplasma urealyticum lacks cell wall, belongs to the taxonomic class Mollicutes, and is one of the smallest self-replicating prokaryotes (33). Among Mollicutes, U. urealyticum is unique in its ability to hydrolyze urea and requires urea to support growth (16). In 1954, Shepard first isolated U. urealyticum from the urethras of patients with nongonococcal urethritis (29). Since then, there has been intense interest in determining what role U. urealyticum might play in human diseases, particularly in the pathogenesis of genital tract infectious diseases.Because U. urealyticum is an inhabitant of the human lower genital tract, infections are considered to be sexually transmitted and occur more frequently during fertile ages. Although the contributory role of U. urealyticum in infertility has yet to be conclusively established, considerable data have been compiled to support the theory that U. urealyticum can cause infertility (10,11,40,41). Early epidemiologic studies have indicated that U. urealyticum was linked to human reproductive failure on the basis of higher frequencies of isolation from infertile versus fertile couples (11). Friberg and Gnarpe (10) found that U. urealyticum existed in the semen of 76% of the husbands from 50 couples with unexplained infertility. Xu et al. (40) also observed significantly higher frequency of U. urealyticum infection among infertile males (549 of 1,416) compared to fertile controls (34 of 375). Furthermore, they demonstrated that U. urealyticum not only could adhere to the membrane of spermatozoa but also could interfere with sperm motility an...

Effects of Ureaplasma urealyticum lipid-associated membrane proteins on rheumatoid arthritis synovial fibroblasts

“…26 Pannus was observed in the cartilage, and synovial fibroblasts had adhered to (and destroyed) the cartilage. 26 Other studies have confirmed these findings; [27][28][29][30] some showed that the Journal of International Medical Research 41 (5) pathology was similar to the synovium of RA patients. 29,30 From these studies, [26][27][28][29][30] it could be concluded that in the model of human-SCID mice arthritis, human synovium implants and RASFs induced destructive arthritis in SCID mice.…”

Homology between cattle bull sperm and bacterial antigenic proteins viz a viz possible role in immunological infertility

“…Immunoblotting data confirm the cross‐reactivity of 75, 72, 44, 40, 33, 30, 25, 18, and 14 kDa antigens between spermatozoa and E. coli, Bacillus, Staphylococcus bacteria (Figure and Table ) . Cross‐reactive antigens of 61, 50, and 25 kDa were reported between U. urealyticum and human sperm membrane proteins (Shi et al, ). As tested cows and heifers had exposure to general infections, therefore, antibodies developed to common antigens of spermatozoa and bacteria may be a reason for the cross‐reaction of these proteins with their purified IgG.…”

“…The cross‐reactive antigens between Ureaplasma urealyticum (U. urealyticum) and human sperm have also been reported (Ye, Lu, Zhu, Peng, & Wang, ). There was cross‐reactivity of U. urealyticum (61, 50, 25 kDa) and human sperm membrane proteins (Shi et al, ). Infection with chlamydia and mycoplasma increases the seminal antisperm antibody in humans and hence significantly reduces the sperm‐egg penetrating ability (Soffer et al, ).…”

“…was cross-reactivity of U. urealyticum (61,50,25 kDa) and human sperm membrane proteins (Shi et al, 2007). Infection with chlamydia and mycoplasma increases the seminal antisperm antibody in humans and hence significantly reduces the sperm-egg penetrating ability (Soffer et al, 1990).…”

Bactericidal/permeability-increasing protein originates in both the testis and the epididymis and localizes in mouse spermatozoa

“…As described previously,13 on the 35 th day, the titer of the antiserum was measured using an enzyme-linked immunosorbent assay. The antiserum was purified with protein A affinity chromatography according to the manual (Millipore, Billerica, MA, USA).…”