TLR9 and cystic fibrosis: In addition, Faust and colleagues have shown that depletion of CpG dinucleotides from the AAV vector reduces activation of Toll-like receptor 9 (TLR9)-mediated adaptive immune responses after intramuscular injection of the vector, leading to reduced inflammation and prolonged gene expression.68 However, it remains to be assessed whether CpG-depleted AAV vectors offer any advantages for CF gene therapy.