Process development and cGMP manufacturing of a recombinant ricin vaccine: An effective and stable recombinant ricin a-chain vaccine—RVEc

Authors

  • Michael M. Meagher,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Javier G. Seravalli,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • S. Todd Swanson,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Roger G. Ladd,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Yogender P. Khasa,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Mehmet Inan,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Jay C. Harner,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Scott K. Johnson,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Kevin Van Cott,

    1. University of Nebraska-Lincoln Biological Process Development Facility, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0668
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  • Changhong Lindsey,

    1. Office of Regulated Studies, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702
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  • Robert Wannemacher,

    1. Dept. of Integrated Toxicology, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011
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  • Leonard A. Smith

    Corresponding author
    1. Senior Research Scientist (ST), Office of Chief Scientist, United States Army Medical Research Institute of Infectious Diseases, and Medical Countermeasures Technology, United States Army Medical Research and Material Command, Fort Detrick, MD 21702-5011
    • Senior Research Scientist (ST), Medical Countermeasures Technology, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011
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  • This article is a U.S. Government work, and, as such, is in the public domain in the United States of America.

Abstract

Ricin is a potent toxin and a potential bioterrorism weapon with no specific countermeasures or vaccines available. The holotoxin is composed of two polypeptide chains linked by a single disulfide bond: the A-chain (RTA), which is an N-glycosidase enzyme, and the B-chain (RTB), a lectin polypeptide that binds galactosyl moieties on the surface of the mammalian target cells. Previously (McHugh et al.), a recombinant truncated form of RTA (rRTA1-33/44-198 protein, herein denoted RVEa™) expressed in Escherichia coli using a codon-optimized gene was shown to be non-toxic, stable, and protective against a ricin challenge in mice. Here, we describe the process development and scale-up at the 12 L fermentation scale, and the current Good Manufacturing Practice (cGMP)-compliant production of RVEc™ at the 40 L scale. The average yield of the final purified bulk RVEc™ is approximately 16 g/kg of wet cell weight or 1.2 g/L of fermentation broth. The RVEc™ was >99% pure by three HPLC methods and SDS-PAGE. The intact mass and peptide mapping analysis of RVEc™ confirmed the identity of the product and is consistent with the absence of posttranslational modifications. Potency assays demonstrated that RVEc™ was immunoprotective against lethal ricin challenge and elicited neutralizing anti-ricin antibodies in 95–100% of the vaccinated mice. Published 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011.

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