A Pox Upon Our House

Although the date 9-11 defines modern terrorism, the date 10-8 marks a turning point in biological terror. On October 8, 2001, the FBI linked terrorism with the death of a man killed by anthrax bacteria. Bioterrorism haunted the nation in the following weeks, eventually forcing the closure of offices in the U.S. Capitol.

“I had been at the Senate Russell Building just hours before the offices were closed,” said Dennis Hruby, a microbiologist at Oregon State University. “I’d been testifying at the request of Senator Kennedy on the bioterrorism threat of smallpox.”

Smallpox has plagued humanity for millennia, killing more people than all the world’s wars combined.

During the mid-1960s, in the midst of the Cold War, the world launched an all-out assault against this global enemy. A multi-billion dollar campaign ensued until, in 1975, scientists isolated the last smallpox case on earth. Eradicating the disease was a triumph of modern science. Nations throughout the world began disposing of their stores of smallpox virus and vaccines. Finally, the last known stocks of smallpox virus existed in only two places…at the Centers for Disease Control in Atlanta and at the Research Institute for Viral Preparations in Moscow.

“Smallpox has been eradicated. Or has it?” asks Hruby.

A researcher with OSU’s Agricultural Experiment Station, Hruby’s knowledge of poxviruses has put him on the front lines of those preparing the nation for a possible outbreak of smallpox.

“No one has been vaccinated in the U.S. for more than 30 years, and the vaccinations of older Americans may have lost some potency,” said Hruby. “The population has become immunilogically naïve. And most of the world’s supply of the vaccine has been destroyed.”

Long before the events of 9-11 and 10-8, the U.S. government had grown concerned about the possible use of smallpox as a weapon against an unvaccinated world population.

Concern arose in 1994, when a defector from the Soviet Union came west with shocking news. As other nations were destroying their last stocks of smallpox virus, the Soviets were producing tons of the virus to use as weapons. In 1980, the year vaccinations ended globally, the Soviet government embarked on a secret program to grow smallpox and adapt it for use in intercontinental ballistic missiles.

The defector, scientist Ken Alibeck, described a Soviet facility capable of producing tons of smallpox virus and a research program seeking to produce more virulent strains. It is not known if any of the experimental virus landed in hostile hands after the breakup of the Soviet Union.

Hruby outlined a possible scenario.

OSU’s Dennis Hruby, in his SIGA lab, tracks cells infused with a fluorescent green virus. If the compound he is testing successfully inhibits the virus, the cells will turn black. Photo: Lynn Ketchum		Woman with smallpox. Photo: History and Special Collections Div., Louise M. Darling Biomed Lib., UCLA

“Let’s say the disease were introduced tomorrow at JFK airport in New York City,” he said. “The contagion could be spread easily through the ventilation system and inhaled by hundreds of unsuspecting people. Incubation period of the disease is about two weeks, so infected travelers would have dispersed throughout the world before any symptoms showed up.”

At first, smallpox appears deceptively benign, like a cold or the flu. Soon a rash appears, starting in the mouth and spreading to the face, limbs, and trunk. The spots swell with fluid and harden. People used to think that if the spots stayed distinct the victim had a good chance of surviving, but if they ran together and, if bleeding erupted beneath the skin, death was certain.

“Doctors would be slow to diagnose a disease that hasn’t been seen for more than a generation,” continued Hruby. “By the time the scattered cases were diagnosed and corroborated, many times more people would have been infected and dispersed. The disease would erupt around the world in waves of two-week intervals. Most of the people who were exposed would contract the illness, and many would die.

“It’s a scary business,” said Hruby.

Smallpox is caused by the variola virus. The vaccine that helped eradicate smallpox was made from vaccinia, a relatively weak virus. Inoculation with vaccinia caused a single pock at the site of injection, which scabbed after about ten days, leaving a vaccination scar and immunity to both vaccinia and variola. Most people over 40 still carry the scar on their upper arms, although for some of us, the immunity may be wearing off.

“It’s a tremendous vaccine, essentially responsible for eradicating smallpox from the face of the earth,” said Hruby. “That said, it’s a dangerous vaccine.”

The vaccinia vaccine has always included a dose of risk. Complications include a deadly form of eczema, encephalitis, heart disease, and death. Although the probability is extremely small, the U.S government declared in 1971 that the risk of these side effects was greater than the risk of contracting smallpox. A year later, vaccinations ended in the U.S.

Mass innoculations ended in the United States in 1972. Photo: National Archives (540703)		First responders receive vaccinations as researchers race to develop an anti-viral treatment for smallpox. Photo: Master Sgt. Keith Reed, USAF

Today, according to the Centers for Disease Control, at least 320,000 Americans would be vulnerable to serious side effects, and as many as 15,000 could die, if the government were to reinstitute nationwide smallpox vaccinations using the vaccinia vaccine.

“The government is not going to vaccinate all Americans and take that risk for a disease they may never see,” said Hruby. “But the government would like to have a drug ready to treat the disease if it were to show up.”

Drugs and vaccines work differently. Vaccinations protect people before they are exposed to a disease and build immunity against future contact. Smallpox vaccinations can last 10 to 20 years, sometimes longer, according to Hruby. In contrast, drugs treat people after they’ve been exposed to the pathogen, when the body doesn’t have time to build immunity. Currently, there are no drugs to treat smallpox.

In 2000, the National Institutes of Health (NIH) sent out a request for proposals from labs willing to help develop a new anti-viral drug to fight smallpox. Dennis Hruby’s work was already heading in that direction.

For the past 20 years, Hruby’s lab in OSU’s Department of Microbiology has worked with NIH to learn how invading microbes infect cells and cause disease. Because most diseases are caused by either viruses or bacteria, Hruby has developed a model for each. His bacterial model is based on the Streptococci group of bacteria that cause diseases ranging from the schoolyard scourge “strep throat” to necrotizing fasciitis, or “flesh eating bacterium.” Much of this part of his work focuses on developing broad-spectrum drugs to combat the problems associated with emerging antibiotic resistance.

His viral model is based on the poxvirus vaccinia, the virus that helped eradicate smallpox.

“Universities don’t develop drugs; they do basic research,” said Hruby. “And companies that develop drugs don’t do basic research.” So when NIH offered the grant to develop an anti-viral drug, they were looking for a partnership of research and development. In 2000, Hruby joined forces with SIGA Technologies, a Manhattan-based drug development company, as their chief scientific officer. OSU would do the research and SIGA would develop the drugs.

“Our proposal was funded, and then 10-8 happened. That accelerated everything,” said Hruby.

Graduate research assistant Chelsea Byrd applies purple stain to virus-infected cells to help her track the effect of anti-viral drugs. Photo: Lynn Ketchum		OSU's Dennis Hruby Photo: Lynn Ketchum

Soon after the initial $600,000 grant from NIH, the U.S. Army Medical Research Material Command granted the OSU/SIGA partnership $1.6 million to develop a smallpox anti-viral drug.

“Since work with HIV has demonstrated that anti-viral drugs are effective, we can take the same approach with viruses like smallpox,” Hruby said.

Smallpox depends on enzymes to shape proteins so the virus can grow. Hruby’s approach is to identify these critical enzymes and use them as targets for compounds that will inhibit the enzyme function and halt the growth of the virus. However, poxviruses share about 90 percent of their enzymes with human cells. So drugs that inhibit poxvirus enzymes have a 90 percent chance of inhibiting human enzymes as well.

“A successful drug must kill the virus and NOT kill the patient,” said Hruby. And the drug should be in the form of a pill rather than an injection, so it can be distributed and administered quickly in the event of a national emergency.

Hruby’s lab has identified two potential enzymes and is developing compounds that target them. Testing begins with individual cells, then moves on to living tissue.

“We’ve engineered a virus that is fluorescent, so the cells glow bright green. If a compound inhibits the virus growth, the cells turn black. Results from these tests are very easy to read and quantify.

“And because we are testing live cultures, we know that the anti-viral compound is nontoxic, because it doesn’t kill the cells, and we know it’s bioavailable, because it crosses the cell membrane to where the virus lives. So we’re several steps toward developing a safe and effective drug.

“We currently have a molecule in hand that is more active against poxvirus than anything that is known, and it does not kill the host cells. We are getting ready to test the compound at Fort Detrick, Maryland [at the U.S. Army Infectious Disease Center], where it will be tested against other poxviruses, and ultimately against smallpox in tissue culture.”

Hruby is quick to emphasize that his lab in Corvallis does not use or test the smallpox virus, variola. Research using smallpox requires a very high level of security, and Fort Detrick is one of the only places in the United States secure enough to conduct such tests.

Not only is the federal government providing secure facilities to test these new drugs, they are also providing a market to buy the drugs after development.

“It’s not like developing a heart medicine that lots of people will buy and use for the rest of their lives,” said Hruby. “These smallpox drugs may never be used.”

The government wants these drugs available as soon as possible, and research and development is on the fast track. Normally, it would take five to eight years to bring a new drug to the public, but a smallpox drug is different. For one thing, there are no people with smallpox on which to test a new drug. The Food and Drug Administration recently passed new rules to speed the process of testing and licensing drugs for biodefense.

Now it’s a race. Not only is Hruby’s lab racing against a possible national emergency, they are racing against other labs developing similar drugs.

“From a strictly commercial standpoint, being first is important,” said Hruby. “The only use for this drug is as a biodefense agent, so the major purchaser will be the U.S. government or health agencies. And the government is not going to buy ten different poxvirus drugs. They’re going to buy the first effective one that comes on the market and stockpile it. So if you want to sell your drug, you’ve got to be the first to be approved.”

A drug like this could have a market value of up to a billion dollars, according to Hruby. “OSU and SIGA share the patent rights, so royalties could be important revenue for OSU.”

Their work has applications besides the fight against terrorism.

“The recent appearance of monkeypox in North America reminds us that these poxviruses are ubiquitous, and the threat of new diseases can come from nature as well as from a deliberate attack,” said Hruby. “We share the planet with viruses that cause AIDS, SARS, monkeypox, and more. They can appear any time. We need drugs on the shelf and ready to go when these viral diseases show up.”