Expression of recombinant mouse sperm protein sp56 and assessment of its potential for use as an antigen in an immunocontraceptive vaccine

Abstract

Recombinant mouse sp56 protein was produced for testing as an antigen in an immunocontraceptive vaccine. The coding sequence for the mature sp56 protein was cloned into the bacterial expression system pFLAG using a PCR-based method on mouse testis cDNA. Polyclonal antisera were raised in mice against affinity purified recombinant sp56 fusion protein (sp56FLAG) or an artificial sp56 peptide fused to a carrier protein (KLH) and shown to cross-react to a protein band of 75 kD in detergent extracts of mouse sperm by Western immunoblot analysis under reducing conditions. The antisera to sp56FLAG also immunolocalized over the entire acrosome of mouse sperm. Female BALB/c mice were immunized intraperitoneally with sp56FLAG in a fertility trial with 20 microg sp56FLAG in Freund's Complete Adjuvant and boosted three to five times with 20 microg sp56FLAG in Freund's Incomplete Adjuvant. Litter sizes of sp56FLAG-treated mice were significantly smaller than control-treated animals after five boosts.

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

“…In addition to these findings, reports have shown reduced in vivo fertility in female animals that were immunized with sperm antigens, suggesting the negative impact of the antibodies toward animal fertility (e.g., PH20 [21], FA-1 [22], SP17 [23], sp56 [24], and YLP (12) [25]). Moreover, reactive immunoglobulins toward some of these proteins have been identified in sera from subfertile women (26), supporting their immunogenicity and increasing concerns about their potential deleterious effect upon fertilization.…”

Effect of immunization against prostate- and testis-expressed (PATE) proteins on sperm function and fecundity in the rat

“…This strategy is based on the induction of antibodies against epididymal or testicular proteins so that they do not associate with the sperm surface or mask them to prevent interaction with other proteins for maturation. Examples include: antisperm antibodies (Vazquez-Levin (Luo et al, 2012), eppin (O'Rand et al, 2006), Bin1b (Li et al, 2001), FA-1 (Naz and Zhu, 1998), LDH-C4 (O'Hern et al, 1997), P10G (O'Rand et al, 1993, A9D (Lea et al, 1998), SP56 (Hardy and Mobbs, 1999), 80 kDa HSA (Khobarekar et al, 2008), YLP12 (Naz and Chauhan, 2002), zona pellucida proteins (Eade et al, 2009), and Izumo (Naz, 2008;Wang et al, 2009). We previously demonstrated that the rat PATE proteins are localized on the sperm surface and are predicted to play a role in sperm function (Rajesh and Yenugu, 2012).…”

REVIEW ARTICLE: Status of Contraceptive Vaccines

“…Notable among these are FA-1, 15 YLP 12 , 16 P10G, 17 A9D, 18 and SP56. 19 Most of these active immunization studies were carried out in the mouse model. The findings of these studies are summarized in Table I.…”