Self-complementary adeno-associated virus vectors containing a novel liver-specific human factor IX expression cassette enable highly efficient transduction of murine and nonhuman primate liver.
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 x 10(10) 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.
Nathwani
Amit C
AC
Department of Haematology, University College London, 98 Chenies Mews, London, United Kingdom, WC1E 6HX. a.nathwani@ucl.ac.uk
Gray
John T
JT
Ng
Catherine Y C
CY
Zhou
Junfang
J
Spence
Yunyu
Y
Waddington
Simon N
SN
Tuddenham
Edward G D
EG
Kemball-Cook
Geoffrey
G
McIntosh
Jenny
J
Boon-Spijker
Mariette
M
Mertens
Koen
K
Davidoff
Andrew M
AM
D000818:Animals; D000229:Dependovirus / Q000235:genetics / Q000502:physiology*; D005164:Factor IX / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D016679:Genome, Viral; D002836:Hemophilia B / Q000628:therapy*; D006801:Humans; D008099:Liver / Q000502:physiology* / Q000821:virology*; D008253:Macaca mulatta; D008297:Male; D051379:Mice; D011323:Primates; D014161:Transduction, Genetic / Q000379:methods
D005164:Factor IX