Sperm-Trapping Antibodies!

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The most effective female contraceptives (birth control pills, Intrauterine devices, and vaginal rings) are usually hormone-based and come with a host of different problems. When used for a long period of time, they may cause weight gain, mental health issues, and increased chances of developing breast cancer. They may even be contraindicated for some women due to their medical conditions, leaving them with no choice but faulty barrier methods.

Therefore, the need for a powerful female contraceptive that does not put the user’s health at risk is clear. Well, Dr. Shreshta and her team from the University of North Carolina may have a solution.

Immune infertility

Immune infertility is a condition where women produce sperm-binding antibodies in their reproductive tract which prevents the cells to reach an egg and fertilize it.

Dr. Shreshta’s and colleagues isolated these antibodies and modified them by adding 6-10 extra antigen-binding sites(Fabs), in order to increase their sperm trapping potential.

They then tested their antibodies against human sperm cells in vitro and found that their agglutination potential had increased by 10 to 16% as compared to their isolated predecessor.

The team then used a sheep model for testing. They inoculated the animal with the engineered antibodies –called highly multivalent IgGs (HM-IgGs) – and then tested their in vivo potential against human sperm inside the sheep’s vagina.
They found that a 33μg dose of the 10-Fabs antibody reduced sperm by 99.9%.

Delivering the antibodies

Following these successful phases, the researchers will now move on to human trials. Instead of introducing these antibodies as part of an immunization protocol, however, they intend to deliver them through “intravaginal rings (IVR) that afford steady release of [antibodies] over a duration spanning the fertility window in most women to create a contraceptive product akin to the NuvaRing but without the hormones,” according to the study.

Furthermore, the advantage is clear. The article explains that “Rather than altering physiological mechanisms underpinning fertility such as hormones, topical immunocontraception should afford rapid return to fertility, unlike the months of delay experienced by some women even after they have discontinued the use of long-acting hormonal contraceptives.”

The researchers also believe that these innovative HM-IgGs may have further biomedical applications beyond contraception. Let’s wait and see!

Source: Science Translational Medicine



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