Download Single mutation can affect antibody`s ability to bind to and neutralize

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