Human Anthrax Vaccine Development in Korea National Institute of Health
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Anthrax has been considered one of most likely bio-warfare weapons. It’s potential use as an agent of bio-terrorism was highlighted in 2001 by a series of postal mailing attacks in United States. Anthrax is a highly lethal infectious disease caused by the spore-forming bacterium Bacillus anthracis. After entering the host, anthrax spores germinate inside macrophages, which transport the bacteria to regional lymph nodes. Released bacilli then multiply extracellularly, secrete high levels of exotoxins, and spread systemically in the bloodstream. The exotoxin is composed of three distinct proteins, protective antigen (PA), edema factor (EF), and lethal factor (LF), which are secreted separately as nontoxic monomers. The binding of LF or EF to PA results in formation of active lethal toxin or edema toxin, respectively, which causes massive edema and organ failure. Among these toxin proteins, because PA can elicit a protective immune response against both anthrax toxins, it is the target antigen of existing anthrax vaccines. Current human anthrax vaccines available in the US and Europe consist of alum-precipitated supernatant material from cultures of a toxigenic, nonencapsulated strain of B. anthracis. The major component of human anthrax vaccine that confers protection is PA. A second generation human vaccine using the recombinant PA is being developed.
In 2002, Korea National Institute of Health (KNIH) started to develop human anthrax vaccine for national stockpiling against an emergency situation, The developing vaccine is a second generation vaccine of which major component is a purified recombinant PA. For a mass production of the PA from B. anthracis, KNIH established an expression system with Bacillus brevis - pNU212 and developed functional assays and animal models for vaccine efficacy tests. With the cooperation of a private sector, Green Cross Co., the development of manufacturing process, preclinical and clinical trial phase I studies were completed. In 2011, clinical trial phase II study will be started in Seoul National Hospital, Seoul Korea. After clinical studies, KNIH is planning to receive a conditional licensure from Korea Food and Drug Administration and to start stockpiling of this vaccine for emergency use.