Immunogenicity of a multi-component recombinant human acrosomal protein vaccine in female Macaca fascicularis.

A vaccine formula comprised of five recombinant human intra-acrosomal sperm proteins was inoculated into female monkeys to test whether specific antibodies to each component immunogen could be elicited in sera and whether antibodies elicited by the vaccine affected in vitro fertilization. Acrosomal proteins, ESP, SLLP-1, SAMP 32, SP-10 and SAMP 14, were expressed with his-tags, purified by nickel affinity chromatography and adsorbed to aluminum hydroxide. Five female cynomolgus monkeys were inoculated intramuscularly three times at monthly intervals. All five monkeys developed both IgG and IgA serum responses to each recombinant immunogen on Western blots. Each serum stained the acrosome of human sperm and bound to the cognate native protein on Western blots of human sperm extracts. By ELISA, all monkeys developed IgG to each immunogen, with the highest average absorbance values to ESP, SAMP 32 and SP-10, followed by lower values for SLLP-1 and SAMP 14. IgA was also generated to each component immunogen with the highest average absorbance values to SLLP-1 and SP-10. For antigens that induced an IgA response, the duration of the IgA response was longer than the IgG response to the same antigens. This study supports the concept that a multivalent contraceptive vaccine may be administered to female primates evoking both peripheral (IgG) and mucosal (IgA) responses to each component immunogen following an intramuscular route of inoculation with a mild adjuvant, aluminum hydroxide, approved for human use.

Translation and assembly of CABYR coding region B in fibrous sheath and restriction of calcium binding to coding region A.

CABYR is a highly polymorphic, sperm flagellar calcium-binding protein that is tyrosine as well as serine/threonine phosphorylated during capacitation. Six alternative splice variants of human CABYR (I-VI) have previously been identified, involving two coding regions, CR-A and CR-B, separated by an intervening stop codon. It is presently unknown if proteins encoded by the predicted coding region B of CABYR are translated during spermiogenesis, where they localize, or which CABYR isoforms bind calcium. Immunofluorescent and electron microscopic studies using polyclonal antibodies generated to the recombinant c-terminal 198 aa CABYR-B localized the isoforms containing CABYR-B to the ribs and longitudinal columns of the fibrous sheath in the principal piece of the flagellum. Antisera to recombinant CABYR-A and CABYR-B proteins recognized distinct populations of CABYR isoforms encoded by either CR-A alone and/or CR-B as well as a common population of CABYR isoforms. Only the recombinant CABYR-A and not the CABYR-B bound calcium in vitro, which is consistent with the hypothesis that CABYR-A is the only form that binds calcium in sperm. These observations confirmed that, despite the presence of the stop codon in CR-A, splice variants containing CR-B are expressed during spermiogenesis and assemble into the fibrous sheath of the principal piece; however, calcium binding occurs only to those CABYR isoforms containing CABYR-A.