International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


PLENARY PRESENTATION

MONDAY OCTOBER 18

4.15pm – 4.45pm

RNAi DIRECTED THERAPIES FOR HUMAN VIRAL HEPATITIS INFECTION

Grimm D, McCaffrey A, Nakai H, Ehrhardt A, Marion P Kay MA

Depts of Pediatrics and Genetics, Stanford University

RNA interference has great potential for the treatment of viral infections.  Our laboratory has focused on liver directed transfer of siRNAs and the expression of short-hairpin RNAs from the livers of living animals to inhibit transgene expression.  To do this, we injected either the short-inhibitory RNAs or plasmids expressing the short-hairpins along with a plasmid expressing the luciferase transgene, luciferase-HCV fusion gene, or HBV genome into the livers of mice by a hydrodynamic infusion procedure.  We established that:  (1)  RNAi  was functional in whole mammals, (2) Expressed shRNAs were efficient at down-regulating gene expression, suggesting that RNAi-mediated therapies can be adapted to a gene therapy approach, (3) RNAi against hepatitis C virus sequences were inhibitory, and (4) shRNAs directed against hepatitis B virus inhibited viral HBV DNA replication in the liver. To further pursue a gene therapy approach against hepatitis virus infection in animal models, a transgenic mouse that contains and replicates the HBV genome was used for further study. shRNAs expressed from  pol III  promoters were cloned into first generation or helper dependent (adenoviral gene deleted)  adenovirus  and  AAV pseudotype 8  recombinant viral vectors,  and then infused into the HBV transgenic mice.  These three vector systems were selected because they are capable of transducing nearly 100% of the hepatocytes in vivo. Using recombinant  AAV-8 vectors and carefully selecting the appropriate shRNA expression cassette, safe and long-term elimination of the HBsAg from HBV transgenic mice was observed.  HBV DNA titers, liver immunohistochemistry for HBcAg, northern and Southern blots for quantification of HBV nucleic acids are being determined.  Moreover, these studies have revealed important safety considerations. The potential therapeutic value of each of these vectors approaches will be discussed.

[an error occurred while processing this directive]