Tetramer-based analysis of FMDV segments could improve vaccine effectiveness

Researchers from The Pirbright Institute have identified new parts of foot-and-mouth disease virus (FMDV) that stimulate an immune response. Their findings, reported in Immunology, could be used to inform the design of improved vaccines. They also discovered that T helper cells were present in cattle samples four years after the animals had been vaccinated, indicating for the first time that they play a role in long term vaccine protection.

In a collaboration with the University of Miyazaki, Japan, Pirbright scientists focused on understanding the FMD response of T helper cells. These activate other cells in the immune system that fight FMD infection and they can ‘remember’ specific parts of FMDV, contributing to long term immunity in animals. If vaccines can be designed to trigger improved T helper cell responses, they could provide enhanced and longer lasting protection.

The team used man-made molecules called tetramers to establish which virus components the T helper cells responded to. Tetramers each carry a different part of the FMD virus (such as a short segment of a surface protein), which can be used like molecular magnets to ‘catch’ immune cells that recognise them. Scientists used tetramers to pick out individual immune cell types and build up a picture of which T helper cells are stimulated by different parts of the virus capsid.

They found four FMDV molecules that T helper cells recognised, three of which had never been identified before. They also demonstrated that T helper cells were still present in cattle blood samples four years after the animals had been vaccinated against FMD, the first time that the life span of these cells has been studied. This finding adds to the evidence that T helper cells play an important role in long term protection following vaccination.

Article: Mitoma, S., Carr, B. V., Harvey, Y., Moffat, K., Sekiguchi, S., Charleston, B., Norimine, J., Seago, J. (2021). The detection of long-lasting memory foot-and-mouth disease (FMD) virus serotype O-specific CD4+ T cells from FMD-vaccinated cattle by bovine major histocompatibility complex class II tetramer. Immunology, advance online publication, doi: 10.1111/imm.13367

[SOURCE: The Pirbright Institute]