AAV-mediated delivery of optogenetic constructs to the macaque brain triggers humoral immune responses

Abstract

Gene delivery to the primate central nervous system via recombinant adeno-associated viral vectors (AAV) allows neurophysiologists to control and observe neural activity precisely. A current limitation of this approach is variability in vector transduction efficiency. Low levels of transduction can foil experimental manipulations, prompting vector readministration. The ability to make multiple vector injections into the same animal, even in cases where successful vector transduction has already been achieved, is also desirable. However, vector readministration has consequences for humoral immunity and gene delivery that depend on vector dosage and route of administration in complex ways. As part of optogenetic experiments in rhesus monkeys, we analyzed blood sera collected before and after AAV injections into the brain and quantified neutralizing antibodies to AAV using an in vitro assay. We found that injections of AAV1 and AAV9 vectors elevated neutralizing antibody titers consistently. These immune responses were specific to the serotype injected and were long lasting. These results demonstrate that optogenetic manipulations in monkeys trigger immune responses to AAV capsids, suggesting that vector readministration may have a higher likelihood of success by avoiding serotypes injected previously. NEW & NOTEWORTHY Adeno-associated viral vector (AAV)-mediated gene delivery is a valuable tool for neurophysiology, but variability in transduction efficiency remains a bottleneck for experimental success. Repeated vector injections can help overcome this limitation but affect humoral immune state and transgene expression in ways that are poorly understood. We show that AAV vector injections into the primate central nervous system trigger long-lasting and serotype-specific immune responses, raising the possibility that switching serotypes may promote successful vector readministration.

Selective Optogenetic Control of Purkinje Cells in Monkey Cerebellum

“…; Figure 3C, red), but the AAV1 vector had an efficiency of only 49±3% (mean ± S.E. ; Figure 3C, green), possibly related to previous AAV1 injections made in this animal (Calcedo and Wilson, 2013; Mendoza et al, 2017, see data for Monkey F in their Figure 6). These analyses demonstrate that Purkinje cell-specific expression of ChR2 can be achieved with either AAV1 or AAV9 vectors.…”

Intrathymic adeno-associated virus gene transfer rapidly restores thymic function and long-term persistence of gene-corrected T cells

“…Immune responses against AAV capsid serotypes, as well as expressed transgenes, have hampered the success of AAV gene therapy trials. 113 Anti-capsid antibodies have been detected even after AAV injections into regions that are considered to be immune privileged, such as the brain 92 or intravitreal space. 114,115 Nevertheless, the development of immunosuppressive treatments has protected against AAV capsid immunity.…”

“…90 Furthermore, different rAAV serotypes have induced T cell-dependent and independent anti-capsid humoral responses, 91 even when injected into an immuneprivileged organ, such as the brain. 92 Therefore we monitored the presence of anti-capsid antibodies in intrathymic AAV8-treated ZAP-70 2/2 mice as a function of neutralization. Neutralizing factors were defined as serum dilutions that inhibited AAV8 infection by greater than 50%.…”

Chemogenetic inhibition of the amygdala modulates emotional behavior expression in infant rhesus monkeys

“…Screening for AAV Neutralizing antibodies: Nonhuman primates' native immunity has been shown to impact transduction in other CNS tissues (i.e., eye (Kotterman et al, 2015)) and neutralizing antibody response to multiple virus solution intracerebral injections have been directly linked to weak transduction in neurons (Mendoza et al, 2017). However, it is currently unknown whether native immunity to AAVs can impact transduction of neuronal tissue.…”