Hydroxylation of N-acetylneuraminic Acid Influences the in vivo Tropism of N-linked Sialic Acid-Binding Adeno-Associated Viruses AAV1, AAV5, and AAV6.

Estrella Lopez-Gordo,Thomas Weber,Alejandro Orlowski,Arthur Wang,Alan Weinberg,Susmita Sahoo

doi:10.3389/fmed.2021.732095

Estrella Lopez-Gordo, Thomas Weber + Show 4 more

Open Access

https://doi.org/10.3389/fmed.2021.732095

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Journal: Frontiers in Medicine	Publication Date: Dec 21, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Icahn School of Medicine at Mount Sinai

Abstract

Adeno-associated virus (AAV) vectors are promising candidates for gene therapy. However, a number of recent preclinical large animal studies failed to translate into the clinic. This illustrates the formidable challenge of choosing the animal models that promise the best chance of a successful translation into the clinic. Several of the most common AAV serotypes use sialic acid (SIA) as their primary receptor. However, in contrast to most mammals, humans lack the enzyme CMAH, which hydroxylates cytidine monophosphate-N-acetylneuraminic acid (CMP-Neu5Ac) into cytidine monophosphate-N-glycolylneuraminic acid (CMP-Neu5Gc). As a result, human glycans only contain Neu5Ac and not Neu5Gc. Here, we investigate the tropism of AAV1, 5, 6 and 9 in wild-type C57BL/6J (WT) and CMAH knock-out (CMAH−/−) mice. All N-linked SIA-binding serotypes (AAV1, 5 and 6) showed significantly lower transduction of the heart in CMAH−/− when compared to WT mice (5–5.8-fold) and, strikingly, skeletal muscle transduction by AAV5 was almost 30-fold higher in CMAH−/− compared to WT mice. Importantly, the AAV tropism or distribution of expression among different organs was also affected. For AAV1, AAV5 and AAV6, expression in the heart compared to the liver was 4.6–8-fold higher in WT than in CMAH−/− mice, and for AAV5 the expression in the heart compared to the skeletal muscle was 57.3-fold higher in WT than in CMAH−/− mice. These data thus strongly suggest that the relative abundance of Neu5Ac and Neu5Gc plays a role in AAV tropism, and that results obtained in commonly used animal models might not translate into the clinic.

Highlights

Adeno-associated viruses (AAVs) are non-pathogenic, have relatively low immunogenicity, and trigger long-term transgene expression in non-dividing cells, even in the absence of integration of the viral DNA into the host genome
Since the use of animal models that mimic the tropism of AAV serotypes and variants in humans are key for the development of AAV gene therapy, we here test the hypothesis that AAV1, AAV5 and AAV6, all of which use sialic acid (SIA) as their primary receptor, display different tropism in cytidine monophosphoN-acetylneuraminic acid hydroxylase (CMAH) knockout mice when compared to wild-type C57BL/6J (WT) mice
We assessed the tropism of N-linked SIA-binding AAV1, 5 and 6 in CMAH−/− mice that, like humans, lack the SIA Neu5Gc

Summary

INTRODUCTION

Adeno-associated viruses (AAVs) are non-pathogenic, have relatively low immunogenicity, and trigger long-term transgene expression in non-dividing cells, even in the absence of integration of the viral DNA into the host genome. As shown by the authors, the failure in therapeutic efficacy was likely due to the inefficient transduction of human cardiomyocytes, since an approximate conversion of number of vector genomes (vg)/μg of total DNA to vg/diploid host genome suggests that

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