Sperm surface antigen (SSA)

Sperm surface antigens (SSAs) are a heterogeneous group of proteins and glycoproteins expressed on the plasma membrane of spermatozoa, where they mediate critical steps in the fertilization process [3, 11]. These antigens facilitate sperm motility, capacitation, the acrosome reaction, and the specific recognition and fusion of the sperm with the oocyte [6, 15]. Due to their sequestration behind the blood-testis barrier, SSAs are highly immunogenic; their exposure to the immune system can lead to the production of anti-sperm antibodies (ASA), a primary cause of immunological infertility [8, 10]. In therapeutic development, SSAs are targeted for non-hormonal immunocontraception, where vaccines aim to induce antibodies that block fertilization [8, 16]. Additionally, many SSAs function as cancer-testis antigens, being aberrantly expressed in various tumors (e.g., ovarian, lung, and breast cancer), making them promising targets for chimeric antigen receptor (CAR) T-cell therapy and other immunotherapies [1, 4].

Other names

Sperm-associated antigenSPAGSperm membrane proteinSperm-specific antigen

Inhibition of sperm-egg binding and fusion, sperm immobilization, complement-mediated sperm lysis, and inhibition of the acrosome reaction