Supplementary files and original datasets in the article <b>“</b><b>Genome-wide characterization of Toll-like receptor genes in </b><b><i>Oreochromis niloticus</i></b><b> and their </b><b>transcriptional response in brain </b><b>following</b><b> </b><b><i>Streptococcus agalactiae </i></b><b>infection”</b>

Phylogenetic analysis classified these genes into five subfamilies: TLR1, TLR3, TLR5, TLR7, and TLR11, with the TLR4 subfamily absent. Integration of transcriptomic and single-cell data revealed that all 19 TLR genes are expressed across a variety of tissues and cells, with 14 of them (excluding <i>TLR1-1</i>, <i>TLR2-3</i>, <i>TLR5S</i>, <i>TLR13-2</i>, and<i> TLR13-3</i>) being expressed in the brain, particularly in the medulla oblongata.

Furthermore, we examined the transcriptional response of these 14 TLR genes following S. agalactiae infection in seven brain regions. Notably, <i>TLR1-2</i>, <i>TLR2-1</i>, <i>TLR5M</i>, and <i>TLR8-1</i> were significantly upregulated (<i>P</i><0.05) following <i>S. agalactiae</i> infection, suggesting their potential association with the tilapia brain’s innate immune defense against <i>S. agalactiae</i>. These findings enhance our understanding of the TLR gene family in tilapia and its role in the brain’s immune response to bacterial invasion.</p>