Antiacrosin antibodies and infertility. II. Gene immunization with human proacrosin to assess the effect of immunity toward proacrosin/acrosin upon protein activities and animal fertility

Objective To assess the effect of antiacrosin antibodies upon proacrosin/acrosin activities and animal fertility. Design Prospective study. Setting Basic research laboratory. Patient(s) A gene immunization (GI) model was developed; mice were injected with the sequence encoding human proacrosin (h-proacrosin), cloned in an expression vector. Intervention(s) Subcloning of h-proacrosin in a eukaryotic expression vector (promoter, CMV; leader sequence, α-1 antitrypsin; pSF2-Acro); GI of female mice with this plasmid. Main Outcome Measure(s) The following parameters were evaluated: [1] adequate conditions for GI protocols, [2] humoral response to GI with pSF2-Acro, [3] protein regions recognized by the antibodies, and [4] effect of antibodies upon proacrosin/acrosin–ZPA binding and amidase activity, and animal fertility. Result(s) Conditions of female mice GI with the proacrosin sequence were established (plasmid purification with anion exchange chromatography and 40 μg of pSF2-Acro per dose) to trigger an immune response, reaching maximum levels at week 9 after the first injection. Antibodies produced by GI recognized human and mouse sperm acrosin systems, inhibited human proacrosin/acrosin interaction with recombinant human ZPA and protease activity, and negatively affected mouse IVF and early embryonic development. In addition, mice immunized with SF2-Acro exhibited a significantly lower size of fetuses. Conclusion(s) Antiacrosin antibodies developed by using GI inhibit human proacrosin/acrosin activities and impair mouse fertility.