NGF and infection: Hohsfield et al. (2013), demonstrated that infection by a lentiviral vector, which overexpressed NGF, showed successful production of effective NGF secretion. In parallel with these findings, lentivirus NGF gene delivery to the cholinergic basal forebrain for 1-year in aged monkeys showed no systemic leakage of NGF or formation of anti-NGF antibodies, nor activation of inflammatory markers in the brain or pain or weight loss (Nagahara et al., 2009a).