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Single mutation can affect antibody’s ability to bind to and neutralize bovine herpes virus What is this research about? As part of its defence against disease-causing organisms, the immune system produces complex proteins called antibodies that can recognize, attach to, and neutralize bacteria and viruses. Binding to the virus or bacteria takes place at a site on the antibody made up of two different protein chains, called the heavy chain (VH) and light chain (VL). Both parts are needed for the antibody to be effective. Through genetic engineering, researchers have developed whole antibodies that are capable of fighting various viruses and bacteria. Unfortunately, the large size of these antibodies makes it hard for them to get to the site of infection. To overcome this problem, scientists are now looking at creating smaller antibody fragments, called single chain variable fragments (scFv), which can bind to the virus or bacteria but also move more easily through the body. In scFv, the heavy and light chains are connected by a very short linker made up of around 12 amino acids. Longer linkers may allow scFv to work individually, while shorter linkers may require two matching scFv to join together to function. What did the researchers do? The researchers used a single chain variable fragment (scFv) that was able to bind to and neutralize bovine herpes virus type 1 (BoHV1), a causative agent of respiratory and genital diseases in cattle. Through genetic engineering, this scFv was modified to have an 18 amino acid linker (scFv3-18L). A nearly identical scFv was also created that had a single mutation in part of the heavy chain - this mutant version was called scFv4m-18 L. Next, researchers tested the ability of both antibody fragments to recognize, bind to, and neutralize BoHV-1 in infected cells grown in the laboratory, compared to an antibody fragment with a 7 amino acid linker (scFv1-7L). What you need to know: Genetically engineered antibody fragments, working either individually or in pairs, were able to effectively bind to and neutralize bovine herpes virus type-1 in infected cells. A single mutation affected the antibody fragment’s ability to neutralize the virus, without changing its ability to recognize and attach to it. Project supported by: A program of the OMAFRA-U of G Partnership. What did the researchers find? The antibody fragment scFv3-18L was able to recognize and bind to BoHV-1, as well as neutralize BoHV-1 in infected cells. A dose of 0.18 μM (micromolar) of scFv3-18L resulted in more than 50% viral neutralization, compared to a dose of 0.1 μM of scFv1-7L for the same effect. Therefore, linker size affected an antibody fragment’s ability to neutralize the virus. The mutated fragment, scFv4m-18L, was also able to neutralize the virus, but the required dose was nearly three times greater. The mutation did not, however, affect the ability of scFv4m-18L to bind to the virus. How can you use this research? Vaccine scientists can use this research to better understand how antibody binding and viral neutralization can be affected by a single mutation. Vaccine developers can further this research by continuing to develop single chain variable fragment (scFv) antibodies against a wide range of viruses and bacteria that infect humans and animals, for the purposes of developing vaccines or diagnostic tests. Article citation: Koti, M., Nagy, E., & Kaushik, A.K. (2011). A single point mutation in framework region 3 of heavy chain affects viral neutralization dynamics of single-chain Fv against bovine herpes virus type 1. Vaccine, 29, 7905-7912. About the University of Guelph researchers: Principal Investigator: Azad Kaushik is an Associate Professor in the Department of Molecular and Cellular Biology at the University of Guelph. Email: [email protected]. Graduate Student: M. Koti Email: [email protected] Collaborator: Eva Nagy is a Professor in the Department of Pathobiology at the University of Guelph. Email: [email protected]. Keywords: Vaccines, antibodies, bovine herpes virus 1, virus neutralization, point mutation, amino acid linker, single-chain variable fragment Cite this work: University of Guelph, Institute for Community Engaged Scholarship (2012). Single mutation can affect antibody’s ability to bind to and neutralize bovine herpes virus. Retrieved from: http://hdl.handle.net/10214/5653 This summary is a project of the Institute for Community Engaged Scholarship (ICES) at the University of Guelph, with project partners: the Catalyst Centre, SPARK Program at the University of Guelph, and the Knowledge Mobilization Unit at York University. This project is part of the Pan-Canadian Research Impact Network. http://csahs.uoguelph.ca/pps/Clear_Research This work is licensed under the Creative Commons Attribution-NoDerivs 3.0 Unported