SARS vaccine tests well in mouse model.

A vaccine that targets the virus responsible for severe acute respiratory syndrome (SARS) stops the infection in mice, scientists report.

Researchers fashioned the vaccine from a piece of viral DNA that includes the gene for a surface protein on the SARS virus. When injected into mice, the DNA becomes housed in mouse cells, which then use the genetic instructions to produce the viral protein. By itself, that protein doesn't cause disease. However, it induces an immune response in the animals that includes production of antibodies and immune cells, says study coauthor Gary J. Nabel of the National Institute of Allergy and Infectious Diseases in Bethesda, Md.

Nabel's team gave mice three injections of the DNA vaccine or of an inert substance over 6 weeks. Thirty days after the last injection, the scientists exposed all the mice to live SAPS virus. The placebo group developed high concentrations of virus in their lungs within 2 days, while the vaccinated mice fended off the pathogen, the researchers report in the April 1 Nature. Antibodies to the surface protein did the work, presumably, by identifying the protein on the live SARS virus and neutralizing the virus before it could invade cells and spread.

Several research teams are experimenting with other SARS vaccines (SN: 1/10/04, p. 28). Some could enter human-safety trials this year.--N. S.