SARS trials lift vaccine hope

A genetically engineered vaccine against SARS has shown promising results in early tests in monkeys and could pave the way for a protective vaccine in humans, according to scientists said.

Two weeks after researchers at the University of Pittsburgh in Pennsylvania injected six rhesus macaques with the vaccine, all of the animals showed a detectable immune system response against the coronavirus that causes severe acute respiratory syndrome (SARS).

"It is our hope that this research will lead to a protective vaccine against SARS," said Dr Andrea Gambotto, who headed the research team.

The SARS outbreak which began in southern China last November killed 774 people and infected 8,098 in some 30 countries, according to the World Health Organization.

China, Hong Kong, Taiwan and Canada were most severely affected by the virus, which spread around the world through international air travel.

Scientists identified the cause of SARS as a new member of the family of coronaviruses, which causes the common cold, and the race began in laboratories around the world to develop a vaccine.

Gambotto and his team in collaboration with scientists at the Centers of Disease Control and Prevention (CDC) in Atlanta genetically altered a common cold virus to express SARS coronavirus antigens. Their results were reported in The Lancet medical journal.

"We genetically engineered a common cold virus and we inserted pieces of the SARS coronavirus," Gambotto explained in an interview.

Six monkeys were injected with the vaccine and received a booster after 28 days. Two other monkeys were given a dummy vaccine and did not show any response.

"After injection, the vaccine acts as a Trojan Horse, first by infecting cells in the body, and then simulating an immune reaction to the delivered SARS antigens, ultimately conferring protection against the disease," Gambotto explained.

The scientists now plan to test the vaccine in ferrets, which can develop symptoms of SARS after being infected. They hope to begin human trials before the end of next year.

Chinese and Canadian scientists have also said they plan to begin tests of a SARS vaccine in humans next year. Global health officials have warned that SARS could reappear.

"This is a very good candidate vaccine," said Gambotto. "It can be produced in a million vaccine doses easily at very low cost."

SARS is treated with the drug ribavirin and steroids. Symptoms include fever, chills, muscle ache, dry cough and breathing difficulties.

Content provided by ArmMed Media
Revision date: 12 December 2007
Last revised by Amalia K. Gagarina, M.S., R.D.