More on DNA vaccination for avian flu
The flu vaccine-making system that serves as the best available protection against a pandemic relies on millions of chicken eggs, takes nine months to produce each year’s flu shots and has changed little since the 18th century.
This creaky system poses a big problem if a new, deadly strain emerges once the annual and inflexible production process begins.
Several biotechnology companies are at work on a new and quicker way of making a flu vaccine they hope can replace one that requires people to be inoculated with the entire influenza virus. Their technique: extract just a few genes from the virus and inject it into people.
The nascent technology, called DNA vaccines, is a form of gene therapy that proponents argue is the best way to overhaul a 50-year-old vaccine manufacturing system.
DNA vaccines were first introduced about 10 years ago as a possible treatment for a variety of diseases, from AIDS to cancer. They worked great in mice, but largely failed to work in humans because the injected genes did not find their way into the cells.
Vijay Samant, chief executive of Vical Inc. in San Diego, said those initial problems have been overcome and his company is testing DNA vaccines in cancer and AIDS patients to battle those diseases.
Gary Nabel et al. have worked on a different modification of the DNA vaccine, priming with DNA vaccine and boosting with a recombinant adenovirus containing the influenza nucleoprotein gene, which is a more highly conserved protein than the hemagglutinin and neuraminidase proteins that are targeted with current vaccines. This vaccine combination worked well in their tests in mice (including challenge with the 1997 H5N1 strain), but again, the problem is that its efficacy in humans is unknown.