At 4 h post-infection, the transcription levels of the TLR2 gene in both primary astrocytes and BV2 cells infected with two S. parasuis strains were significantly higher than those of cells infected with S. suis strain P1/7; conversely, S. suis strain P1/7 induced the highest transcription levels of the TLR2 gene among three strains in primary astrocytes and BV2 cells from 12 h and 8 h post-infection, respectively (Figure 3G,H). Here, TLR2 is linked to infection.