There are seven serotypes of FMD virus (FMDV) that have high mutation rates which constantly generate new FMDV variants. This makes rapid diagnosis essential for vaccinating against the correct type of FMDV and ensuring control policies are put in place quickly.
Previously, ELISA tests have required small animals such as rabbits and guinea pigs to produce antibodies that bind to FMDV enabling the disease to be detected in samples. Each strain of FMDV requires highly specific antibodies which means new antibodies are regularly required to keep up with emerging new strains.
Instead of using animal antibodies, previous research has shown that a protein called integrin αvβ6 can be used to detect the presence of FMDV. This works because integrin αvβ6 is a receptor that universally binds to field strain FMD viruses in order to gain entry into cells. Scientists from Pirbright Institute therefore used a truncated bovine integrin αvβ6 (a shorter, modified cow version of the protein) in their ELISA tests that all FMDV types would bind to.
The researchers have been able to create large amounts of bovine integrin αvβ6 in the lab using a rapid technique called ‘transient cell transfection’. This could make diagnosis of FMD strains cheaper and easier, as only one integrin would be needed to identify all strains of FMDV.
Another major benefit is that animals are not needed to produce bovine integrin αvβ6. This is a huge step towards supporting the 3Rs agenda (Refine, Replace and Reduce) in science regarding the use of animals.
Further experiments are needed to optimise and validate the test for routine FMDV diagnosis, but it is hoped that bovine integrin αvβ6 could eventually be used in the FMDV diagnostic kits.
The researchers also set out to find an alternative to using inactivated FMD virus as a positive control for the integrin diagnostic tests, which is used to confirm the test is working. Previously this required the production of live FMD virus, which is costly since this infectious virus must be produced in a high containment laboratory.
Pirbright Institute scientists successfully demonstrated that modified empty shells of FMD virus (capsids) without any genetic material, can be used instead of the inactivated live virus, as these capsids have the ability to bind to integrin and can be produced without the need for high containment. This could lower the cost for positive control production and make the process faster and more efficient.
Wednesday, August 24, 2016 / Pirbright Institute