Stable replication of the EBNA1/OriP-mediated baculovirus vector and its application to anti-HCV gene therapy.
BACKGROUND
Hepatitis C virus (HCV) is one of the main causes of liver-related morbidity and mortality. Although combined interferon-alpha-ribavirin therapy is effective for about 50% of the patients with HCV, better therapies are needed and preventative vaccines have yet to be developed. Short-hairpin RNAs (shRNAs) inhibit gene expression by RNA interference. The application of transient shRNA expression is limited, however, due to the inability of the shRNA to replicate in mammalian cells and its inefficient transduction. The duration of transgene (shRNA) expression in mammalian cells can be significantly extended using baculovirus-based shRNA-expressing vectors that contain the latent viral protein Epstein-Barr nuclear antigen 1 (EBNA1) and the origin of latent viral DNA replication (OriP) sequences. These recombinant vectors contain compatible promoters and are highly effective for infecting primary hepatocyte and hepatoma cell lines, making them very useful tools for studies of hepatitis B and hepatitis C viruses. Here, we report the use of these baculovirus-based vector-derived shRNAs to inhibit core-protein expression in full-length hepatitis C virus (HCV) replicon cells.


RESULTS
We constructed a long-term transgene shRNA expression vector that contains the EBV EBNA1 and OriP sequences. We also designed baculovirus vector-mediated shRNAs against the highly conserved core-protein region of HCV. HCV core protein expression was inhibited by the EBNA1/OriP baculovirus vector for at least 14 days, which was considerably longer than the 3 days of inhibition produced by the wild-type baculovirus vector.


CONCLUSIONS
These findings indicate that we successfully constructed a long-term transgene (shRNA) expression vector (Ac-EP-shRNA452) using the EBNA1/OriP system, which was propagated in Escherichia coli and converted into mammalian cells. The potential anti-HCV activity of the long-term transgene (shRNA) expression vector was evaluated with the view of establishing highly effective therapeutic agents that can be further developed for HCV gene therapy applications.
Department of Life and Environmental Sciences, Chiba Institute of Technology, Narashino, Chiba, Japan. g0473021FE@it-chiba.ac.jp
Hitoshi
H
Suzuki
Norihiko
N
Matsumoto
Tomoyuki
T
Suzuki
Myint Oo
MO
Chang
Hiroshi
H
Takaku
D016367:Baculoviridae / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D016174:Hepacivirus / Q000235:genetics*; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics; D018741:Replication Origin / Q000235:genetics*; D014758:Viral Core Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D014779:Virus Replication
D019309:Epstein-Barr Virus Nuclear Antigens; D034741:RNA, Small Interfering; D014758:Viral Core Proteins; C069130:nucleocapsid protein, Hepatitis C virus; C417029:EBV-encoded nuclear antigen 1