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78
Potent and Durable RNAi-Mediated
Suppression of Hepatitis B Virus Infection in
a Mouse Model By a Non-Viral Closed-Ended
Linear Duplex (CELiD) DNA Vector
Badriprasad Ananthanarayanan, Michael Graham, Tin Mao,
Vanessa Strings-Ufombah, Shih-Chu Kao, Kermit Zhang,
Peter Roelvink and David Suhy, Benitec Biopharma Ltd
Background: We have previously demonstrated that a
single dose of BB-103, a gene therapy vector using an AAV
capsid to deliver a cassette expressing three anti-HBV short
hairpin RNA (shRNA), can result in the durable and potent
suppression of HBV viral load and HBsAg in a chimeric
mouse model of HBV infection. However, systemic delivery
using viral capsids can be challenging due to manufacturing
complexity, pre-existing neutralizing antibodies, and the
inability to repeat dosing due to induced immunity. Recently,
Closed-Ended Linear Duplex (CELiD) DNA vectors that have
the ability to produce persistent gene expression have been
described. Here, we examined if non-viral CELiD vectors
expressing anti-HBV shRNAs could cause meaningful
suppression of HBV infection in a mouse model. Methods:
CELiD DNA was produced using an optimized baculovirus/
insect cell expression system and downstream purification. In
initial experiments, durability of expression from CELiD DNA
versus plasmid DNA was assessed by luciferase expression
over 6 months. For anti-viral studies, a mouse model of longterm
HBV infection was established in NOD/SCID mice by
Hydrodynamic Injection (HDI) of plasmid DNA encoding the
HBV genome. CELiD DNA expressing the same three anti-
HBV shRNAs as in BB-103 were co-administered with HBV
DNA by HDI. Suppression of HBV infection was assessed
over the course of 10 weeks by weekly monitoring of serum
HBV DNA, HBsAg, and HBeAg. Results: HDI administration
of CELiD DNA encoding a luciferase reporter in a naïve
mouse model produced robust levels of luciferase expression
which persisted for the duration of the 6 month experiment,
while expression from plasmid DNA rapidly declined after
administration. In the HBV model, administration of CELiD
DNA resulted in a 1.75 log decrease (below LLOQ) in serum
HBV DNA compared to control DNA expressing non-targeted
shRNA at day 70. Furthermore, CELiD DNA reduced serum
HBsAg by 1.89 log and HBeAg by 0.89 log (both below LLOQ)
as compared to the control. HBV viral load continued to drop
through the entirety of the 70 day experiment with no rebounds
in serum HBV parameters. Conclusion: Non-viral CELiD DNA
vectors expressing anti-HBV shRNAs produced strong and
persistent knockdown of HBV parameters following a single
administration in the HDI mouse model. This suggests that
CELiD DNA expressing anti-HBV shRNAs, when delivered
by an appropriate liver-directed reagent, may be a promising
therapeutic for chronic HBV infection.
Disclosures:
Badriprasad Ananthanarayanan – Benitec Biopharma: Employment; Benitec
Biopharma: Stock Shareholder
Shih-Chu Kao – Benitec: Employment
Peter Roelvink – 1956: Employment
David Suhy – Benitec Biopharma: Management Position
Disclosure information not available at the time of publication: Michael Graham,
Tin Mao, Vanessa Strings-Ufombah, Kermit Zhang
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发表于 2018-10-6 20:25
