Immune gene expression profiling of PBMC isolated from horses vaccinated with attenuated African horsesickness virus serotype 4.

Development of African horsesickness (AHS) subunit vaccines will have to include a rational approach that uses knowledge of how the virus interacts with the host immune system. The global in vivo immune response induced by attenuated AHSV serotype 4 in horses was characterised using transcriptome sequencing. PBMC were collected with 24h intervals for four days after inoculation and four days after a second boost, 21 days later. Transcriptome data were normalised to the day 0 naïve transcriptome and up- or down-regulated immune genes identified using the CLC workbench. Peak expression was observed 24h after each inoculation. Innate immunity was up-regulated after both inoculations and was characterised by type-1 interferon activation via the RIG-1/MDA5 pathway and the up-regulation of complement cascade components. After the second boost an adaptive immune response could be identified that included the production of cytokines indicative of T helper (Th)1, Th2 and Th17 responses.