Self-complementary adeno-associated virus vectors containing a novel liver-specific human factor IX expression cassette enable highly efficient transduction of murine …

AC Nathwani, JT Gray, CYC Ng, J Zhou, Y Spence… - Blood, 2006 - ashpublications.org
AC Nathwani, JT Gray, CYC Ng, J Zhou, Y Spence, SN Waddington, EGD Tuddenham
Blood, 2006ashpublications.org
Transduction with recombinant adeno-associated virus (AAV) vectors is limited by the need
to convert its single-stranded (ss) genome to transcriptionally active double-stranded (ds)
forms. For AAV-mediated hemophilia B (HB) gene therapy, we have overcome this obstacle
by constructing a liver-restricted mini–human factor IX (hFIX) expression cassette that can be
packaged as complementary dimers within individual AAV particles. Molecular analysis of
murine liver transduced with these self-complementary (sc) vectors demonstrated rapid …
Abstract
Transduction with recombinant adeno-associated virus (AAV) vectors is limited by the need to convert its single-stranded (ss) genome to transcriptionally active double-stranded (ds) forms. For AAV-mediated hemophilia B (HB) gene therapy, we have overcome this obstacle by constructing a liver-restricted mini–human factor IX (hFIX) expression cassette that can be packaged as complementary dimers within individual AAV particles. Molecular analysis of murine liver transduced with these self-complementary (sc) vectors demonstrated rapid formation of active ds-linear genomes that persisted stably as concatamers or monomeric circles. This unique property resulted in a 20-fold improvement in hFIX expression in mice over comparable ssAAV vectors. Administration of only 1 × 1010 scAAV particles led to expression of hFIX at supraphysiologic levels (8I U/mL) and correction of the bleeding diathesis in FIX knock-out mice. Of importance, therapeutic levels of hFIX (3%-30% of normal) were achieved in nonhuman primates using a significantly lower dose of scAAV than required with ssAAV. Furthermore, AAV5-pseudotyped scAAV vectors mediated successful transduction in macaques with pre-existing immunity to AAV8. Hence, this novel vector represents an important advance for hemophilia B gene therapy.
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