Affimers: animal free alternatives to antibodies

Affimers are engineered binding proteins that possess the desirable properties of antibodies, such as high specificity and affinity, whilst avoiding some of the problems commonly associated with antibody use, such as cross-reactivity and fragility. They have similar binding affinities as antibodies and are stable when bound to surfaces. This makes them ideal for applications that require immobilization of a capture reagent, as well as use in a variety of assays that have traditionally used antibodies. Custom Affimers are generated through in vitro selection in a fraction of the time it takes to develop a new antibody and can even be made in cases where it is impossible to raise antibodies: targets do not need to be immunogenic, and toxicity to the host is not an issue.

The production of antibodies as tools for research and development typically involves the immunisation of between one and three animals (usually mice or rabbits, but sometimes sheep, chickens, goats or donkeys) per target. Where an immunisation has been successful, the animal will ultimately be sacrificed. For every Affimer made, these immunisations and subsequent animal sacrifices will have been avoided. 

Through CRACK IT Solutions, Avacta Life Sciences sought partners interested in validating the technology in their own applications, or in developing Affimers in new applications, where traditional animal-derived antibodies would be used. They are now working with the Mary Lion Centre at MRC Harwell on a project to develop Affimers as a new tool for increasing the efficiency of genetically engineered mouse production. This project will develop an Affimer against the hormone inhibin, which regulates the hormone cascade responsible for ovulation, allowing constitutively high levels of expression of follicle stimulating hormone (FSH) and luteinising hormone (LH). This should ultimately result in increasing oocyte ovulation from each mouse, reducing the total number of animals required. If successful, this technique could reduce mouse usage by 80,000 to 100,000 mice per year in the UK alone.

Full details about this CRACK IT Solution can be found on the CRACK IT website.