New technologies promise an end to shortages

By Henry I. Miller – washingtontimes.com 12/7/09

The H1N1 swine flu has sickened at least 22 million and killed almost 4,000 in the United States since April, according to the Centers for Disease Control and Prevention.

The shortage of the promised supplies of H1N1 flu vaccine has led to long waits in clinic lines for many Americans, frantic calls to doctors’ offices, and growing concern that immunization will arrive too late to prevent illness. In high-risk populations such as asthmatics, young children and expectant mothers, that anxiety is fueled by the possibility of life-threatening consequences should they become infected.

Overall, though, we were lucky this time around. Vaccine manufacturers have been able to produce substantial amounts of vaccine in record time and, as flu viruses go, the current H1N1 is tame. But the H1N1 immunization effort should be a wake-up call to health officials: We are woefully unprepared to deal with a true pandemic of a highly lethal virus. We need to modernize the technology used to make vaccines, so that they can be developed and manufactured more quickly. If large numbers of people were being killed by H1N1, shortages of vaccine would cause riots.

The trouble with our current vaccine production system is that it is not rapidly scalable to demand. It is an 80-year-old system that depends on harvesting the vaccine from fertilized chicken eggs. Manufacturers grow the virus in the eggs until there is a sufficiently high titer, and then the virus is harvested, killed and purified.

The entire process takes months. To harvest a suitable amount of vaccine for flu season requires millions of eggs. In 21st century America, we are waging war on a lethal infectious disease with World War I-era technology.

Fortunately, there are two newer, far superior ways to create vaccines.

The first is a process using recombinant DNA, or “gene-splicing,” technology to create a vaccine that induces the body to make its own antigen, and then to produce antibodies to that antigen. Researchers produce DNA of the target virus gene in a laboratory and introduce it into a circle of DNA called a plasmid, which acts as a carrier.

The plasmids containing the viral gene can easily and quickly be grown in large amounts. When the plasmids are injected into the muscle of a subject, they are taken up by cells that use the viral gene to make a viral protein, usually a protein that appears on the surface of the virus. (Sometimes, a second gene is present that directs the synthesis of an internal protein of the flu virus.) The viral protein – which is noninfectious and harmless – enters the bloodstream, where the immune system recognizes it as foreign and starts to make antibodies against it.

If the subject is later exposed to the flu virus, more antibodies are produced and bind to and neutralize the virus. Thus, the plasmid DNA that contains the viral gene is the vaccine.

The entire process, once the viral DNA is isolated, takes only a few days. This process is cost-effective and produces a vaccine with numerous advantages over the traditional versions.

DNA vaccines have a high heat tolerance, which means they can be transported over long distances without becoming inactivated, and can be stored in locations (such as developing countries) that lack refrigeration.

The vaccines are also easily altered in the lab, so that if the virus were to mutate, the genetic code could be changed accordingly and production could resume quickly. Another advantage is that because DNA vaccines do not contain whole viruses, there is no threat of viral infection from an immunization.

Another promising new vaccine process uses cell cultures of various kinds as a stand-in for the eggs in the traditional model. Manufacturers expose animal or insect cells grown in tissue culture to live virus, allow it to multiply and then harvest, inactivate and purify the virus particles.

This method saves time in scaling up to meet vaccine needs and avoids relying on eggs, which is cumbersome and could be vulnerable to infection if there were an outbreak of avian flu – thereby creating unacceptable and possibly lethal delays for the production process.

Federal health officials have already recognized the importance of these two cutting-edge approaches. A recent example is a contract from the U.S. Department of Health and Human Services (HHS) to the drug company Novartis, to support a new vaccine manufacturing facility that utilizes cell-based technology and other new processes to produce vaccine. And in June, HHS awarded a $35 million contract to Protein Sciences to develop and test a vaccine produced from gene-based technology.

These investments – and others like them – are good first steps, but we need to go further. Research and testing of DNA vaccines in particular must be expanded. Other vaccine manufacturers should be encouraged to branch into new technologies. The government should provide support for basic and proof-of-principle research. Even in the short term, expanding the use of gene and cell-based vaccine technologies could lead to a flu season without the threat of vaccine shortages.

Eventually, it might even yield the holy grail of flu vaccines – a “universal” vaccine based on the virus’ internal proteins, so that it is active on many different strains, year after year. Developing these new technologies for mass production is essential if we want to be prepared for the next pandemic.

Dr. Henry I. Miller, a physician and fellow at Stanford University’s Hoover Institution, was an official at the Food and Drug Administration from 1979 to 1994. He is the author of “To America’s Health: A Proposal to Reform the FDA” (Hoover Institution Press, 2000).

DNAWellnessinfo.com Resource: http://www.washingtontimes.com/news/2009/dec/07/better-vaccines-for-the-next-pandemic/

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