Researchers have developed a vaccine that appears to protect against the 1918 "Spanish" influenza virus. Using a mammalian expression system they created a virus-like particle (VLP) that mimics the 1918 influenza virus, prompting the immune system to develop protective antibodies.
This is the first report describing the use of a 1918 VLP vaccine expressed and purified from mammalian cells. The results show that a non-replicating VLP is an effective influenza vaccine against the 1918 virus.
Scientists from the University of Pittsburgh and the Centers for Disease Control and Prevention administered the VLP vaccine to mice and ferrets, which were completely protected from a lethal challenge with the 1918 virus.
VLPs are small packages of artificially produced viral protein. They are assembled either spontaneously using high concentrations of viral protein, or by embedding the protein in a lipid membrane during protein synthesis. When encountered by an immune cell, a VLP looks like a real virus particle, because it is coated in viral protein (the antigen). However, because a VLP lacks DNA or RNA, it is not infectious.
VLP vaccines are made using cell expression systems. This genetic engineering approach, utilizing either mammalian cells or yeast, is often found in the production of vaccines. Cell culture systems are closely controlled, and can be scaled up relatively easily. In contrast, egg-based systems which provide the main source of current influenza vaccines rely on large supplies of fertilised chicken eggs for vaccine production, and are more difficult to control.
This research was presented February 24, 2009 at the ASM Biodefense and Emerging Diseases Research Meeting in Baltimore, MD.
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