Comparison of the ability of adeno-associated viral vectors pseudotyped with serotype 2, 5, and 8 capsid proteins to mediate efficient transduction of the liver in murine and nonhuman primate models

Abstract

A detailed comparison of recombinant adeno-associated viral (rAAV) vectors of serotypes 2, 5, and 8 was performed in mice and nonhuman primates. Differences within the capsid proteins and viral terminal repeats of rAAV-2 and -5 did not significantly influence their ability to transduce murine liver. However, vectors pseudotyped with AAV-8 capsid (rAAV-2/8) mediated transgene expression more rapidly and from lower doses than possible with rAAV-2 and -5, although expression declined from peak values in a distinct dose-dependent manner prior to reaching steady-state levels. Nevertheless, at all time points and vector doses, rAAV-2/8 transgene levels were 17- to 84-fold higher than with rAAV-2 or -5 due to a more rapid conversion of the single-stranded genome to transcriptionally active stable duplex DNA. In nonhuman primates, liver-targeted administration of rAAV-5 and rAAV-2/8 vectors established therapeutic levels of transgene expression. The importance of preexisting serotype immunity was highlighted by the inability to achieve successful transduction in the presence of serotype-specific antibodies, although this impediment was successfully avoided through the use of alternative serotypes. In summary, serotype-specific differences in transduction biology and the appreciation of preexisting immunity will likely influence the selection of the rAAV serotype for future clinical trials.

Early, sustained efficacy of adeno-associated virus vector-mediated gene therapy in glycogen storage disease type Ia

“…30 The gradual loss of double-stranded AAV2/8 vector genomes observed here and previously in the liver of normal mice, which was increased compared to other AAV serotypes, was not accompanied by the sharp decrease in transgene expression associated with a vigorous cellular immune response. 28,31,32 If AAV vector-mediated G6Pase expression gradually wanes following treatment of infants with GSD-Ia, these patients subsequently could receive a 'booster' AAV vector cross-packaged as an alternative AAV serotype because of absence of cross-neutralization by antibodies against different serotypes. 10,33-35 Liver-targeted gene therapy has great potential in GSD-Ia, because of the demonstrated efficacy of G6Pase replacement by liver transplantation.…”

Long-term inhibition of hepatitis B virus in transgenic mice by double-stranded adeno-associated virus 8-delivered short hairpin RNA

“…Similar drop-off in transgene expression was also observed in several studies using single-stranded AAV2/8 pseudotyped as delivery vehicle. 32,52 Our data suggest that reduction in transgene expression was likely RNAi therapy by double-stranded AAV8 for HBV C-C Chen et al due to a gradual loss of the AAV2/8 genome from the liver (Figure 3d). The real mechanism that resulted in the gradual loss of AAV genomes from the transduced liver tissues is currently unknown.…”

Hepatocyte-targeted HFE and TFR2 control hepcidin expression in mice

“…AAV-Hfe was injected through the tail vein of 8-week-old male Hfe Ϫ/Ϫ mice on a 129/SvEvTac (129/S) background. The AAV2/8 vector used in our experiments is specifically targeted to liver and muscle, 43 and the promoter/enhancing elements limit gene expression to hepatocytes. 38 Mice injected with a virus (AAV-c) encoding glutaryl CoA-dehydrogenase, which is unrelated to iron metabolism, and animals not injected served as controls to test whether the vector injection increased hepcidin levels by causing inflammation.…”