Because there is evidence that a one base pair mismatch in siRNA can still effectively reduce mRNA expression (Amarzguioui et al., 2003; Du et al., 2005), both AAV1-C and AAV1-B were examined for effect on HDAC6 levels and tau inclusions in the AD-tau-seeded rat cortical neuron cultures. This evidence concerns the gene HDAC6 and Alzheimer disease.