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Last Updated

15 Mar 2003

Source: Forbes, March 14, 2003


Seeking A Safer Smallpox Vaccine

By Zina Moukheiber

Scientists are trying to devise drugs to protect people who are at risk from the smallpox vaccine. An estimated 40 million Americans could develop serious complications by getting the shot, particularly those with weakened immune systems from AIDS, cancer or organ transplants, and people with skin infections. Complications include respiratory illnesses, debilitating flu-like symptoms and even death.

"We think it's important to find an alternative. If we're forced into mass vaccinations, there will be some bad outcomes," says Catherine Laughlin, chief of virology at the Microbiology and Infectious Diseases division of the National Institute of Allergy and Infectious Diseases (NIAID), a unit of the National Institutes of Health.

Bolstered by a $1.7 billion budget for biodefense (that's up from just $274.5 million last year), the NIH is starting to dole out money to biotech companies. Elusys Therapeutics, a privately held biotech company based in Pine Brook, N.J., is one recipient. On March 10, it announced it received a two-year, $1.2 million grant to start work on a compound that targets the vaccinia virus, the active component of the smallpox vaccine.

Elusys is using its technology to flush the virus out of the blood stream. Its scientists are devising a two-pronged monoclonal antibody--one side binds to the vaccinia, the other to a receptor on a red blood cell. The blood cells then transport the vaccinia to the liver where special enzymes destroy it. Stephen Sudovar, Elusys' chief executive, hopes to have the study completed in mice in two years, before testing the drug in monkeys and later in humans. That will require more money.

San Diego, Calif.-based Chimerix is another privately held startup hoping to develop an alternative to the smallpox vaccine. In 1998, the U.S. Army Medical Research Institute of Infectious Diseases found that cidofovir, a Gilead Sciences (nasdaq: 2. GILD - news - people ) antiviral drug that treats eye infections in AIDS patients, helped monkeys recover from the poxvirus. The drug prevents the virus from replicating in the body by blocking the protein that makes viral DNA. But cidofovir has drawbacks: It's an injectable and does serious damage to kidneys.

Now Karl Hostetler, a Chimerix founder, has developed an oral form of cidofovir by attaching it to a fatty molecule that also makes it less toxic on the kidneys. On March 12, the company disclosed at the American Society for Microbiology conference on bioterrorism that the drug prevented cowpox infection (similar to smallpox) in mice when given five days before exposure to the virus. It thwarted the disease when taken three days after infection. Chief Executive George Painter says Chimerix is now waiting for a $6 million grant from NIAID to further development. He hopes to have the drug available to humans in 18 months.

Others are trying to develop safer versions of the vaccine. U.K.-based Acambis (nasdaq: ACAM - news - people ) has started work on a weakened form of the vaccine, so-called modified vaccinia ankara. The MVA virus doesn't replicate in the body the way regular vaccinia does. People got MVA shots before the U.S. government halted the smallpox vaccination program in 1972. However, there's no data on the vaccine's efficacy. NIAID awarded Acambis a three-year $9.2 million contract in February to make and test the vaccine in early human trials. The government plans to stockpile 30 million doses of the MVA vaccine for emergency use. This is Acambis' second contract; the first requires it to produce a smallpox vaccine.

VaxGen (nasdaq: VXGN - news - people ) of Brisbane, Calif. and Japan's Chemo-Sero-Therapeutic Research Institute announced in December that they plan to make a vaccine using a safer strain of vaccinia. The company, which revealed disappointing results with its HIV vaccine in February, expects to start clinical trials of a smallpox vaccine in the U.S. early next year.