Possible SARS Vaccine Breakthrough
Genetically Altered Virus Triggers SARS Immune Response in Monkeys
Dec. 4, 2003 -- In what may prove to be an important step toward the development of a protective SARS vaccine, researchers have genetically altered a common cold virus that appears to trigger a SARS-fighting immune response in monkeys.
Six weeks after getting vaccinated to this cold-causing virus -- engineered by scientists at the University of Pittsburgh School of Medicine and the CDC to resemble parts of the same coronavirus that causes potentially fatal SARS -- each of the six inoculated rhesus monkeys were found to have immune cells and antibodies against SARS. Meanwhile, two others getting a dummy vaccine did not.
"It is our hope that this research will lead to a protective vaccine against SARS," says project leader Andrea Gambotto, MD, of the Molecular Medicine Institute of the University of Pittsburgh. "This is the first real vaccine that's been somewhat validated by peer-review scientists."
This research is especially promising because of how the vaccine affected the monkeys' immune system, which is similar to that of humans.
"Not only did they develop antibodies that neutralize the SARS coronavirus, but they also developed a T-cell response," Gambotto tells WebMD. These T-cells are the body's foot soldiers in fighting a host of infections.
"It's a virologist's wish to have a vaccine with both these responses. Some vaccines work only on antibody response, but for other viral infections, it's also necessary to have a T-cell response. This is important, because we don't yet know which response is necessary with SARS, or if both are."
His preliminary experiment was just completed in September, but it was rushed to publication in this week's The Lancet because of its promising results and potential global implications.
Rapid Spread of SARS
In the 10 months since SARS was first reported in China, it has spread to more than two dozen countries -- affecting some 8,100 people and killing at least 774, according to the CDC. While that outbreak has since been contained, some experts worry that it could re-emerge.
Gambotto's findings couldn't be more timely -- announced just months after the specific SARS coronavirus was identified, prompting researchers from around the world to scramble to develop a vaccine that could protect against this baffling ailment.
The cold virus his team employed is frequently used in many vaccines. "It's known to be safe and could be produced in large quantities at a relatively low cost," he says.
The next phase of research is now starting: To test the vaccine in ferrets, which just three weeks ago were shown by Dutch researchers to develop SARS symptoms after being infected with the SARS-coronavirus -- unlike the "healthy" monkeys initially used.
"This is definitely a good first step in the right direction and proof of action -- that they could get a good immune response to the present coronavirus that's linked to SARS," says Michael J. Rybak, PharmD, director of the Anti-Infective Research Laboratory at Wayne State University and past-president of the Society of Infectious Disease Pharmacists. He was not involved in Gambotto's research.
"The kicker, of course, is that there may be a new SARS virus six months from now, so this vaccine might offer only partial protection against that," Rybak tells WebMD. "That's the reason we don't have a good cold vaccine or why we need to change the influenza vaccine every year. These viruses can change rapidly."