Testing influenza vaccination at the single-cell level
There are a number of seasonal flu vaccines available for human use. Yet they are hampered by the inherent ability of the influenza virus to mutate, thereby evading host immune responses. This leads to virus subtype-specific immunity and necessitates repeated vaccinations every year to achieve sufficient protection. Central to the anti-flu immune response are T lymphocytes that either aid viral clearance or help B lymphocytes in mounting an antibody response. The key objective of the EU-funded TCDIFLU project was to study the T cell differentiation profiling of CD4+ and CD8+ T lymphocytes at the single-cell level after flu vaccination. Using mice immunised with the flu vaccine H1N1 with or without adjuvant, scientists analysed flu-specific CD8+ T cells purified from the vaccination site draining lymph nodes. Screening individual cells with the quantitative single-cell multiplex real-time polymerase chain reaction (RT-PCR) method the researchers searched for the presence of 18 different biomarkers. These had been carefully selected following an extensive literature search. As expected, the different immunisation regimens resulted in different frequency of flu-specific CD8 T cells and different gene expression profiles. This was particularly evident on the activation status of these cytolytic T cells as well as on the presence of memory T cells. TCDIFLU work provides important information regarding immunisation with seasonal flu vaccine, with special consideration of the effect of adjuvants. The project findings can have important ramifications for the design of future vaccines and their modification in order to obtain a desired immune response.
