TLR9 and viral infectious disease: Stimulation with TLR agonists has been shown to provide protection from some viral infections, such as hepatitis B virus (through TLR3, TLR4, TLR5, TLR7, or TLR9) [27], herpes simplex virus encephalitis (through TLR3) [28], lethal influenza virus (through TLR3 or TLR9) [29], HIV strains Bal and Jago (through TLR3) [30], and hepatitis C virus (through TLR7) [31].