Intravenous administration of an AAV-2 vector for the expression of factor IX in mice and a dog model of hemophilia B

Abstract

Previous experiments have demonstrated the stable expression of factor IX (FIX) protein in mice and canine models of hemophilia B following portal vein gene transfer with a recombinant adeno-associated virus (rAAV) vector encoding FIX. Here, we present the results of studies that further optimized the rAAV vector transgene cassette used to express FIX and explored the use of the less-invasive intravenous (i.v.) route of vector administration for the treatment of hemophilia B. First, a liver-specific promoter was evaluated in conjunction with cis-acting regulatory elements in mice. Constructs that included both the b-globin intron and the woodchuck hepatitis virus post-transcriptional regulatory element resulted in the highest level of FIX expression in vivo. Using this optimized vector, we demonstrate that i.v. injection was feasible for hepatic gene transfer in mice, achieving 70-80% of portal vein expression levels of FIX. In further studies using the Chapel Hill strain of hemophilia B dogs, we demonstrate for the first time FIX expression and partial correction of the bleeding disorder following i.v. administration of an AAV vector.

Immune responses to gene therapy vectors: influence on vector function and effector mechanisms

“…The intravenous route seems to be associated with similar transgene expression efficiency, suggesting a low level of immunity against the vector. 45 Finally, the neutralizing effect may vary with the degree of accessibility of the antibodies within the target tissues. This may explain the strong neutralization seen in the liver and lungs and the far weaker neutralization in the retina and brain, as antibodies have limited access to these last two sites.…”

Salivary glands as a potential gene transfer target for gene therapeutics of some monogenetic endocrine disorders

“…However, the delicate nature and lifesustaining role of these highly differentiated organs along with current biotechnology limitations render such approaches unappealing, especially with respect to non-life threatening hormone deficiencies. Various tissues such as muscle, liver or lung have thus far been primarily targeted to overcome this obstacle (Barzon et al 2000, Auricchio et al 2002, Goldspink 2003, Harding et al 2004.…”

Rapamycin control of transgene expression from a single AAV vector in mouse salivary glands

“…Conversely, serotype 2 adenoassociated viral (AAV2) vectors mediate stable transgene expression in several tissues, including liver, 10 muscle, 11 eye, 12 as well as SGs. 2 Indeed, after SG gene transfer, rAAV2 vectors confer functional transgene expression, 13,14 with only a modest immune response, 15 and mediate long-term, transgene expression in mice.…”