Abstract
BackgroundVoluntary control of fertility is of paramount importance to the modern society. But since the contraceptive methods available for women have their limitations such as urinary tract infections, allergies, cervical erosion and discomfort, a desperate need exists to develop safe methods. Vaginal contraceptives may be the answer to this problem, as these are the oldest ways of fertility regulation, practiced over the centuries. With minimal systemic involvement, these are also the safest. Natural substances blocking or impairing the sperm motility offer as valuable non-cytotoxic vaginal contraceptives. Antimicrobial peptides (AMPs) isolated from plants, animals and microorganisms are known to possess sperm immobilizing and spermicidal properties. Following this, in the quest for alternative means, we have cloned, over expressed and purified the recombinant sperm agglutinating factor (SAF) from Staphylococcus warneri, isolated from the cervix of a woman with unexplained infertility.MethodsGenomic library of Staphylococcus warneri was generated in Escherichia coli using pSMART vector and screened for sperm agglutinating factor (SAF). The insert in sperm agglutinating transformant was sequenced and was found to express ribonucleotide-diphosphate reductase-α sub unit. The ORF was sub-cloned in pET28a vector, expressed and purified. The effect of rSAF on motility, viability, morphology, Mg++-dependent ATPase activity and acrosome status of human sperms was analyzed in vitro and contraceptive efficacy was evaluated in vivo in female BALB/c mice.ResultsThe 80 kDa rSAF showed complete sperm agglutination, inhibited its Mg2+-ATPase activity, caused premature sperm acrosomal loss in vitro and mimicked the pattern in vivo showing 100% contraception in BALB/c mice resulting in prevention of pregnancy. The FITC labeled SAF was found to bind the entire surface of spermatozoa. Vaginal application and oral administration of rSAF to mice for 14 successive days did not demonstrate any significant change in vaginal cell morphology, organ weight and tissue histology of reproductive and non-reproductive organs and had no negative impact in the dermal and penile irritation tests.ConclusionThe Sperm Agglutinating Factor from Staphylococcus warneri, natural microflora of human cervix, showed extensive potential to be employed as a safe vaginal contraceptive.
Highlights
IntroductionSince the contraceptive methods available for women have their limitations such as urinary tract infections, allergies, cervical erosion and discomfort, a desperate need exists to develop safe methods
Voluntary control of fertility is of paramount importance to the modern society
S. warneri was grown in Luria Broth (LB) at 37 °C/180 rpm for 72 h, following which it was centrifuged at 10,000 xg for 10 min at 4 °C
Summary
Since the contraceptive methods available for women have their limitations such as urinary tract infections, allergies, cervical erosion and discomfort, a desperate need exists to develop safe methods. Female contraceptive methods include intrauterine devices (IUDs), barriers, sterilization, hormone-based treatment (oral/injectable) and insert contraceptives. Barrier methods of contraception are though effective and suffer from certain side effects such as difficulty in insertion, allergic reactions to latex or polyurethane, vaginal irritation, cervical erosion, urinary tract infections and rarely toxic shock syndrome, if the device is left set up for a really long time [4]. Every contraceptive method in use today has shortcomings, and collectively they leave major voids in the ability of people to control fertility safely, effectively, and in culturally acceptable ways throughout their reproductive life. There is need to provide woman with safe and effective alternatives
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