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| Research Summary | Patents |
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Research Summary
Employing the tetracycline repressor, tetR, and the full-length hCMV major immediate-early promoter that contains two tandem tet operators (tetO) downstream of the TATA element, we established a novel tetracycline-inducible gene expression system in mammalian cells, trademarked as T-RExTM by Invitrogen Inc., Carlsbad, CA. In T-RExTM, binding of tetR to the tetO in the absence of tetracycline suppresses gene expression from the tetO-bearing promoter, whereas in the presence of tetracycline the tetR-mediated suppression of gene expression is released, leading to over three orders of magnitude of induction in gene expression by tetracycline. T-REx can be used to regulate gene expression in various basic and clinical applications. More than 1500 laboratories worldwide have used the T-REx system or its related technology and resulted in at least 125 publications.
Using the T-REx gene switch technology, we have established two major research programs focusing on developing 1) novel strategies in genetic engineering HSV recombinant viral vaccines in prevention of HSV infections; and 2) safer and clinically more effective HSV-1 oncolytic virus for tumor therapy. Additionally, we also developed a replication-defective HSV-1 viral vector for delivering therapeutic genes into various cell types and tissues in a manner that expression of a therapeutic gene can be effectively on- and off-regulated by tetracycline.
1. Development of novel HSV recombinants as vaccines against HSV
infections.
During the past decades, many studies have focused on the development of various HSV recombinant viruses as potential vaccine candidates against HSV infection. However, the ability of these recombinants to establish life-long latent infection and their replication-competent nature in the context of wild-type HSV infection raise a critical concern for the use of these recombinants in humans, especially as a therapeutic vaccine in individuals who have been latently infected with HSV. With the aim of greatly increasing the safety of HSV recombinant vaccine virus while retaining the capability of expressing a broad array of viral gene products, we constructed a novel class of HSV-1 recombinant CJ83193 that expresses the dominant-negative mutant polypeptide of HSV-1 origin binding protein UL9 under the control of the T-RExTM . CJ83193 is self-limiting in normal cells and can prevent the replication of wild-type HSV-1 and HSV-2 in co-infected cells. We recently generated a much-improved CJ83193-like HSV-1 recombinant, CJ9-gD, which is completely replication-defective, cannot establish detectable latent infection in vivo, and expresses significantly higher levels of the HSV-1 major antigen gD than did CJ83193. CJ9-gD is a significantly more effective vaccine than CJ83193 in preventing HSV-1 infection and herpetic disease in mouse models of HSV-1 ocular and intravaginal infections. The efficacy of CJ9-gD in prevention of primary HSV-1 and HSV-2 disease has been further confirmed in guinea pig models of HSV-1 and HSV-2 infection.
2. Development of regulatable oncolytic HSV recombinants for tumor
therapy.
Oncolytic viruses are genetically modified viruses that preferentially replicate in host cancer cells, leading to the production of new virus and ultimately, cell death. Currently, oncolytic viruses able to kill only tumor cells while leaving normal cells intact are NOT available because deletion of genes that impair replication of these viruses in normal cells also results in a significant decrease in viral oncolytic activity for targeted tumor cells. Consequently, the therapeutic doses of existing oncolytic viruses for use in clinical applications are significantly restricted. Clearly, the availability of an oncolytic virus whose replication can be tightly controlled and adjusted pharmacologically both systemically and in the localized tumor microenvironment would offer greatly increased safety and therapeutic efficacy. Using the T-RExTM gene switch technology, we constructed a novel oncolytic HSV-1 recombinant, KTR27, whose replication can be tightly controlled and regulated by tetracycline. KTR27 can achieve 1,000 - 350,000-fold tetracycline-dependent viral replication in various human tumor cell lines, while little viral replication is detected in infected growth-arrested normal human cells. The efficacy of KTR27 in anti-tumor therapy has been demonstrated not only in a xenograft model of human non-small cell lung cancer in nude mice, but also in a syngeneic melanoma model in immunocompetent DBA/2 mice. The goal of this research program is to further explore and develop this novel tetracycline-regulatable oncolytic HSV-1 recombinant for tumor therapies.
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Patents
Yao F. Tetracycline Repressor Regulated Mammalian Cell Transcription and Viral Replication Switch.
U.S. Patent Number 5,972,650, 10/26, 1999.
National Patent.
Licensees (Research Reagents):
Invitrogen Inc. Carlsbad, CA (Research reagents)*
* On the basis of tetracycline repressor-regulated mammalian cell transcription switch technology (U.S. Patent #5,972,650), Invitrogen Inc. developed T-RExTM (Tetracycline-Regulated Expression) system. Since it was on market in April, 1999, over 1500 laboratories have acquired the T-RExTM system from Invitrogen Inc.
The T-REx technology has been used in more than 125 publications including Journals Cell, Nature, PNAS, MCB, JCB, NAR, JV, Oncogen, and others.
Yao F. Tetracycline Repressor Regulated Mammalian Cell Transcription and Viral Replication Switch.
U.S. Patent Number 6,251,640 B1, 6/26, 2001.
Yao F. Tetracycline Repressor Regulated Mammalian Cell Transcription and Viral Replication Switch.
U.S. Patent Number 6,444,871, 9/3, 2002.
Yao F. Tetracycline-regulated gene expression in recombinant HSV-1 vector. U.S. Patent Pending.
Yao F. A novel regulatable oncolytic HSV recombinant for cancer therapy.
U.S. Patent Pending.
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Funding
5 R01 AI050880 (Yao) 12/1/03 - 11/30/08
NIH/NIAID
Self-limiting, and Dominant-negative HSV Recombinants
Role: PI
5 R01 GM51449-10 (Eriksson) 3/01/05 - 2/28/09
NIH
Cutaneous Wound Repair with Transgenic Skin Cells in Pigs
Role: Co-PI
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Selected Publications
1. Yao F*, Sevensjo T, Winker T, Lu M, Eriksson C, Eriksson E. Tetracycline repressor, tetR, rather than the tetR-mammalian cell transcription factor fusion derivative, regulates inducible gene expression in mammalian cells. Hum. Gene Ther. 1998; 9:1939-1950.
2. Yao F**, Eriksson E. A novel anti-herpes simplex virus type 1 (HSV-1) specific HSV-1 recombinant. Hum Gene Ther. 1999; I0:1811-1818.
3. Yao F**, Eriksson E. Inhibition of herpes simplex virus type 2 (HSV-2) viral replication by the dominant-negative mutant polypeptide of HSV-1 origin-binding protein. Antiviral Res. 2002; 53:127-133.
4. Augustinova H, Hoeller D, Yao F**. The dominant-negative HSV-1 recombinant CJ83193 can serve as a safe and effective vaccine against wild-type HSV-1 infection in mice. J Virol. 2004; 78:5756-5765.
5. Yao F**, Theopold C, Hoeller D, Bleiziffer O, Lu Z.M. Highly efficient regulation of gene expression by tetracycline in a novel replication-defective herpes simplex viral vector. Mol. Ther. 2006; 13:1133-1141.
6. Yao F**, Pomahac B, Visovatti S, Chen M, Johnson S, Augustinova H, Svensjo T, and Eriksson E. Systemic and localized induction gene expression by tetracycline with tetR-mediated transcription repression switch. J Surg. Res. 2007; 138:267-274.
7 . Brans R, Eriksson E, Yao F**. Immunization with a dominant-negative recombinant Herpes Simplex Virus (HSV) type 1 protects against HSV-1 Skin Disease in Guinea Pigs. J Invest Derma. 2008.
8. Lu ZM, Brans R, Murakami N, Akhrameyeva N, Xu XM, Yao F**. High-level expression of glycoprotein D by a dominant-negative HSV-1 virus augments its efficacy as a vaccine against HSV-1iInfection. J Invest Derma. In press.
* Co-corresponding author. ** Corresponding author.
To access a complete list of Dr. Feng Yao's publications, please click here.
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This page was last modified on 9/12/2008
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