Capsid Serotype and Timing of Injection Determines AAV Transduction in the Neonatal Mice Brain

Abstract

Adeno-associated virus (AAV) mediated gene expression is a powerful tool for gene therapy and preclinical studies. A comprehensive analysis of CNS cell type tropism, expression levels and biodistribution of different capsid serotypes has not yet been undertaken in neonatal rodents. Our previous studies show that intracerebroventricular injection with AAV2/1 on neonatal day P0 results in widespread CNS expression but the biodistribution is limited if injected beyond neonatal day P1. To extend these observations we explored the effect of timing of injection on tropism and biodistribution of six commonly used pseudotyped AAVs delivered in the cerebral ventricles of neonatal mice. We demonstrate that AAV2/8 and 2/9 resulted in the most widespread biodistribution in the brain. Most serotypes showed varying biodistribution depending on the day of injection. Injection on neonatal day P0 resulted in mostly neuronal transduction, whereas administration in later periods of development (24–84 hours postnatal) resulted in more non-neuronal transduction. AAV2/5 showed widespread transduction of astrocytes irrespective of the time of injection. None of the serotypes tested showed any microglial transduction. This study demonstrates that both capsid serotype and timing of injection influence the regional and cell-type distribution of AAV in neonatal rodents, and emphasizes the utility of pseudotyped AAV vectors for translational gene therapy paradigms.

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

“…Based on our studies with AAV8 and those of our collaborators, delaying the injections not only diminishes the spread of virus from the ventricle, but will also bias the transduction from neurons to astrocytes 6,7 . Therefore we recommend injecting on the day of birth for optimal neuronal expression.…”

“…The method was first described by John Wolfe and Marco Passini in 2001, where they suggested small particle size of AAV allowed it to diffuse within the cerebral spinal fluid as it passes from the lateral ventricles through the immature ependymal barrier and into the brain parenchyma 4,5 . Intraventricular injection of AAV within the first 24 hr after birth yields widespread viral transduction of neural subsets spanning every region of the brain, from the olfactory bulbs to the brain stem 6,7 . Virally-delivered transgenes are expressed and active within days of injection and persist for up to a year after transduction.…”

Lipoprotein lipase in hypothalamus is a key regulator of body weight gain and glucose homeostasis in mice

“…CNS neuron-specific LPL-depleted (NexLpl −/− ) mice were generated by crossing the Lpl loxP mice with transgenic mice having the brain-specific expression of Cre recombinase driven by the regulatory sequences of Nex (also known as Neurod6), a gene that encodes a neuronal basic helix-loop-helix (bHLH) protein [14]. Agrp −/− mice [15] Viral production Adeno-associated viruses (AAVs) of the serotype 2/9, known to have a neuronal tropism, were used [16,17]. AAV Cre-enhanced green fluorescent protein (eGFP), was used to induce a recombination within the MBH in Lpl loxP mice.…”

Viral vectors for therapy of neurologic diseases

“…In general, transport across the BBB is higher in younger individuals (Hordeaux et al, 2015). Irrespective of the injection route, there are multiple reports suggesting that injection of AAV9 at P0 (post-natal day 0) in mice results in widespread neuronal transduction, while administration at older ages results primarily in glial and endothelial cell transduction (IV: Foust et al, 2009; Bevan et al, 2011; Samaranch et al, 2012; ICV: Chakrabarty et al, 2013). The switch away from neuronal transduction at older ages results in loss of therapeutic efficacy of AAV9-based approaches for some neurodegenerative diseases such as SMA where therapy is highly dependent on motor neuron transduction (Foust et al, 2010).…”