Chemistry: molecular biology and microbiology – Virus or bacteriophage – except for viral vector or...
Reexamination Certificate
2000-12-13
2004-02-03
Housel, James (Department: 1648)
Chemistry: molecular biology and microbiology
Virus or bacteriophage, except for viral vector or...
C435S239000, C435S069300, C435S325000, C536S023200, C536S024500, C536S025200, C536S025300, C424S204100
Reexamination Certificate
active
06686190
ABSTRACT:
INTRODUCTION
1. Technical Field
The present invention relates to methods for the production of virus for vaccine production in cell culture.
2. Background
Effective control of influenza pandemics depends on early vaccination with the inactivated virus produced from newly identified influenza strains. However, for more effective pandemic control, improvements in the manufacturing and testing of the vaccine are needed. Influenza viruses undergo very frequent mutations of the surface antigens. Consequently, vaccine manufacturers cannot stock-pile millions of doses for epidemic use. Current influenza control methods demand constant international surveillance and identification of any newly emergent strains coupled with vaccine production specific for the newly identified strains. Current influenza vaccine production, which requires the use of embryonated eggs for virus inoculation and incubation, is cumbersome and expensive. It can also be limited by seasonal fluctuations in the supply of suitable quality eggs. Thus, for production of mass doses of monovalent vaccine in a short time, it would be advantageous to develop alternate, egg-independent production technology. In this respect, production of an influenza vaccine on a stable cell line may solve many of the problems in mass production. However, the yield of human influenza viruses on tissue culture is disappointingly much lower than in embryonated eggs (Tannock et al. Vaccine 1985 3:333-339). To overcome these limitations and improve the quality of vaccines, it would be advantageous to develop cell culture lines which provide an enhanced yield of virus over those currently available.
In using mammalian cell lines for whole virion vaccine production, a common problem for vaccine manufacturers is that mammalian cells have intrinsic antiviral properties, specifically, the interferon (IFN) system, which interferes with viral replication. IFNs can be classified into two major groups based on their primary sequence. Type I interferons, IFN-&agr; and IFN-&bgr;, are encoded by a super family of intronless genes consisting of the IFN-&agr; gene family and a single IFN-&bgr; gene. Type II interferon, or IFN-&ggr;, consists of only a single type and is restricted to lymphocytes (T-cells and natural killer cells). Type I interferons mediate diverse biological processes including induction of antiviral activities, regulation of cellular growth and differentiation, and modulation of immune functions (Sen, G. C. & Lengyel, P. (1992)
J. Biol. Chem.
267, 5017-5020; Pestka, S. & Langer, J. A. (1987)
Ann. Rev. Biochem.
56, 727-777). The induced expression of Type I IFNs, which include the IFN-&agr; and IFN-&bgr; gene families, is detected typically following viral infections. Many studies have identified promoter elements and transcription factors involved in regulating the expression of Type I IFNs (Du, W., Thanos, D. & Maniatis, T. (1993)
Cell
74, 887-898; Matsuyama, T., Kimura, T., Kitagawa, M., Pfeffer, K., Kawakami, T., Watanabe, N., Kundig, T. M., Amakawa, R., Kishihara, K., Wakeham, A., Potter, J., Furlonger, C. L., Narendran, A., Suzuki, H., Ohashi, P. S., Paige, C. J., Taniguchi, T. & Mak, T. W. (1993)
Cell
75, 83-97; Tanaka, N. & Taniguchi, T. (1992)
Adv. Immunol.
52, 263-81). However, it remains unclear what are the particular biochemical cues that signify viral infections to the cell and the signaling mechanisms involved (for a recent review of the interferon system see Jaramillo et al. Cancer Investigation 1995 13:327-337).
IFNs belong to a class of negative growth factors having the ability to inhibit growth of a wide variety of cells with both normal and transformed phenotypes. IFN therapy has been shown to be beneficial in the treatment of human malignancies such as Kaposi's sarcoma, chronic myelogenous leukemia, non-Hodgkin's lymphoma and hairy cell leukemia as well as the treatment of infectious diseases such as papilloma virus (genital warts) and hepatitis B and C (reviewed by Gutterman Proc. Natl Acad Sci. 91:1198-1205 1994). Recently, genetically-engineered bacterially-produced IFN-&bgr; was approved for treatment of multiple sclerosis, a relatively common neurological disease affecting at least 250,000 patients in the U.S. alone.
IFNs elicit their biological activities by binding to their cognate receptors followed by signal transduction leading to induction of IFN-stimulated genes (ISG). Several of them have been characterized and their biological activities examined. The best studied examples of ISGs include a double-stranded RNA (dsRNA) dependent kinase (PKR, formerly known as p68 kinase), 2′-5′-linked oligoadenylate (2-5A) synthetase, and Mx proteins (Taylor J L, Grossberg S E.
Virus Research
1990 15:1-26.; Williams B R G.
Eur. J. Biochem.
1991 200:1-11). Human Mx A protein is a 76 kD protein that inhibits multiplication of influenza virus and vesicular stomatitis virus (Pavlovic et al. (1990)
J. Viol.
64, 3370-3375).
2′-5′ Oligoadenylate synthetase (2-5A synthetase) uses ATP to synthesize short oligomers of up to 12 adenylate residues linked by 2′-5′-phosphodiester bonds. The resulting oligoadenylate molecules allosterically activate a latent ribonuclease, RNase L, that degrades viral and cellular RNAs. The 2-5A synthetase pathway appears to be important for the reduced synthesis of viral proteins in cell-free protein-synthesizing systems isolated from IFN-treated cells and presumably for resistance to viral infection in vivo at least for some classes of virus.
PKR (short for protein kinase RNA-dependent) is the only identified double-stranded RNA (dsRNA)-binding protein known to possess a kinase activity. PKR is a serine/threonine kinase whose enzymatic activation requires binding to dsRNA or to single-stranded RNA presenting internal dsRNA structures, and consequent autophosphorylation (Galabru, J. & Hovanessian, A. (1987)
J. Biol. Chem.
262, 15538-15544; Meurs, E., Chong, K., Galabru, J., Thomas, N. S., Kerr, I. M., Williams, B. R. G. & Hovanessian, A. G. (1990)
Cell
62, 379-390). PKR has also been referred to in the literature as dsRNA-activated protein kinase, P1/e1F2 kinase, DAI or dsI for dsRNA-activated inhibitor, and p68 (human) or p65 (murine) kinase. Analogous enzymes have been described in rabbit reticulocytes, different murine tissues, and human peripheral blood mononuclear cells (Farrel et al. (1977)
Cell
11, 187-200; Levin et al. (1978)
Proc. Natl Acad. Sci. USA
75, 1121-1125; Hovanessian (1980)
Biochimie
62, 775-778; Krust et al. (1982)
Virology
120, 240-246; Buffet-Janvresse et al. (1986)
J. Interferon Res.
6, 85-96). The best characterized in vivo substrate of PKR is the alpha subunit of eukaryotic initiation factor-2 (eIF-2a) which, once phosphorylated, leads ultimately to inhibition of cellular and viral protein synthesis (Hershey, J. W. B. (1991)
Ann. Rev. Biochem.
60, 717-755). PKR can phosphorylate initiation factor e1F-2&agr; in vitro when activated by double-stranded RNA (Chong et al. (1992)
EMBO J.
11, 1553-1562). This particular function of PKR has been suggested as one of the mechanisms responsible for mediating the antiviral and antiproliferative activities of IFN-&agr; and IFN-&bgr;. An additional biological function for PKR is its putative role as a signal transducer. Kumar et al. demonstrated that PKR can phosphorylate I&kgr;B&agr;, resulting in the release and activation of nuclear factor &kgr;B (NF-&kgr;B) (Kumar, A., Haque, J., Lacoste, J., Hiscott, J. & Williams, B. R. G. (1994)
Proc. Natl. Acad. Sci. USA
91, 6288-6292). Given the well-characterized NF-&kgr;B site in the IFN-&bgr; promoter, this may represent a mechanism through which PKR mediates dsRNA activation of IFN-&bgr; transcription (Visvanathan, K. V. & Goodbourne, S. (1989)
EMBO J.
8, 1129-1138).
The catalytic kinase subdomain of PKR (i.e., of p68 (human) kinase and p65 (murine) kinase) has strong sequence identity (38%) with the yeast GCN2 kinase (Chong et al. (1992)
EMBO J.
11, 1553-1562; Feng et al. (1992)
Proc. Natl. Acad. Sci. USA
Bozicevic Field & Francis LLP
Foley Shanon
Francis Carol L.
Housel James
The Regents of the University of California
LandOfFree
Methods for enhancing the production of viral vaccines in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods for enhancing the production of viral vaccines in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for enhancing the production of viral vaccines in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305086