The antibody fragment (inexperienced) utilized by the researchers attaches to the egg shell of oocytes (growing eggs). Credit score: Luca Jovine
A brand new examine from Karolinska Institutet exhibits how a small antibody fragment can block fertilization by concentrating on a key protein on the floor of the egg. This discovery brings a nonhormonal contraceptive one step nearer to actuality. The examine has been revealed within the Proceedings of the Nationwide Academy of Sciences.
Within the examine, the researchers describe how a modified antibody fragment can block fertilization by concentrating on the protein ZP2 on the floor of the egg. “Our study shows how a small antibody fragment can block fertilization by targeting ZP2, a key protein in the outer layer of the egg that is involved in both sperm binding and blocking polyspermy,” says Luca Jovine, Professor of Structural Biology on the Division of Drugs, Huddinge (MedH).
The researchers have used X-ray crystallography to map the interplay between the antibody IE-3, which is understood to stop fertilization in mice, and ZP2 on the atomic degree. A modified, smaller model of the antibody (scFV) was discovered to be equally efficient, blocking fertilization in 100% of IVF checks with mouse eggs. As a result of it lacks the immune-triggering Fc area of the complete antibody, scFV minimizes potential unwanted side effects.
“Despite its small size, the fragment remained effective, reducing potential side effects,” explains Jovine. These findings present a foundation for a focused, reversible contraceptive methodology that avoids hormone-related dangers.
Present strategies of contraception depend on hormones, which may trigger unwanted side effects similar to temper modifications, complications or elevated danger of blood clots. Blocking fertilization on the floor of the egg has been proposed instead, however antibodies have been deemed unsuitable resulting from attainable immune responses triggered by their Fc area.
The following step within the analysis is to develop an identical antibody that targets human ZP2 and check whether or not its scFV fragment can block fertilization in human IVF. If that is profitable in IVF experiments, the following part will give attention to assessing security, stability and potential supply strategies, bringing researchers nearer to a nonhormonal contraceptive methodology for human use.
Extra info:
Elisa Dioguardi et al, Structural foundation of ZP2-targeted feminine nonhormonal contraception, Proceedings of the Nationwide Academy of Sciences (2025). DOI: 10.1073/pnas.2426057122
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Modified antibody fragment blocks fertilization, paving approach for nonhormonal contraceptive (2025, April 14)
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