BETHESDA, Maryland — ; An experimental nasal immunization for the deadly SARS virus that began in China in 2002 has proven effective in a test on monkeys, suggesting that a human vaccine might work best if it comes in a nasal spray, a new study reported Friday.
A study published in The Lancet medical journal found that four African green monkeys given a single dose of the vaccine and then infected four weeks later with the SARS virus developed neutralizing antibodies and showed no symptoms of the virus.
Four monkeys in a control group that didn't get the vaccine developed signs of "viral shedding," which indicates the presence of the SARS coronavirus. The vaccine is created by inserting a protein from the SARS virus into a modified parainfluenza virus.
Researchers from the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Maryland said the results represented "a very significant advance." This is the first vaccine they have tested on monkeys.
"This study shows that delivering the vaccine directly to the respiratory tract can effectively protect primates from SARS," said Brian R. Murphy, co-chief of the NIAID Laboratory of Infectious Diseases and one of the authors of the study. "With more research, we hope to develop a vaccine based on this approach that could be used to rapidly immunize first responders and other medical personnel, helping them control a potential outbreak."
Murphy said that the vaccine in its current form would be most effective in young children. Most adults have some level of immunity to HPIV3 from childhood infections that likely would inhibit an effective immune response to an HPIV3-based SARS vaccine.
But Murphy and his colleagues are planning to conduct clinical studies of BHPIV3 and other potential intranasal vaccine delivery systems, including some that should efficiently immunize adults.
"In the long run, we want to establish a weakened respiratory virus vector that all people are susceptible to," he said. "That way, we can quickly develop vaccines for numerous diseases by simply inserting the protective genes of those viruses into our generalized vector."
SARS has infected more than 8,000 people and killed more than 770 around the world since being identified in China in 2002. Last month, scientists in China injected four volunteers with another experimental SARS vaccine, the first such trials on humans.