Swine influenza: study examines the adaptive immune response of pigs

Researchers at the Pirbright Institute investigated the adaptive immune response of pigs to swine influenza virus and identified T cells which are important for fighting infection and for long term protection.

Published in Mucosal Immunology, the study defines four different types of CD8 T cells and the tissues where the cells are found. Results showed that the pig immune response differs from that seen in small animal models such as mice or ferrets, which are not natural hosts for influenza. The researchers say this highlights the importance of using a natural host where possible to gain a more accurate understanding of the disease.

Researchers revealed both the location of CD8 T cells in different pig tissues and how they behave in response to infection. Previously it was thought that the number of T cells in the lungs declines rapidly after infection, however the research shows this is not the case, suggesting longer lasting protection against future infection.

Scientists also explored how CD8 T cells reacted in response to infection by examining differences in gene expression over time. Gene expression was found to be linked to the production of cytokines and production of different cells in the immune system, in particular tissue resident memory (TRM) cells. TRM cells do not circulate in the blood, but rather remain in tissues such as the lung, providing local protection from infection. Despite these cells having distinct differences from other T cell populations, they are not a completely stable population of cells and continue to change while they are in tissues.

Responses to respiratory immunisation were also explored. It was demonstrated that nasal vaccination can result in high numbers of CD8 T cells in the airway, but does not result in a whole-body immune response as would be seen with an injection directly into the muscle.

Dr Elma Tchilian, Head of the Mucosal Immunology group at Pirbright said: “These findings may prove to be crucial for the design of future vaccines against respiratory diseases. Tissue resident memory (TRM) cells are important in respiratory diseases such as flu and COVID-19 and identifying, in detail, where they are located in a relevant animal model is important for our understanding of disease in pigs. This knowledge is also highly relevant to human disease. For the first time we describe the distribution of porcine cells involved in the immune response and their activity over the course of natural infection or vaccination and these are important knowledge gaps to fill.”

The work was supported by the UK Research and Innovation Biotechnology and Biological Sciences Research Council, the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences, the Townsend-Jeantet Prize Charitable Trust (Charity Number 1011770), and a Medical Research Council Grant.

Article: Martini, V., Edmans, M., Gubbins, S., Jayaraman, S., Paudyal, B., Morgan, S., McNee, A., Morin, T., Rijal, P., Gerner, W., Sewell, A. K., Inoue, R., Bailey, M., Connelley, T., Charleston, B., Townsend, A., Beverley, P., Tchilian, E. (2022). Spatial, temporal and molecular dynamics of swine influenza virus-specific CD8 tissue resident memory T cells. Mucosal Immunology, advance online publication, doi: 10.1038/s41385-021-00478-4

[SOURCE: The Pirbright Institute]

Posted in NewsTagged