Viral enzyme tackles strep throat.

With shapes reminiscent of the Apollo lunar landers, viruses called bacteriophages settle onto a bacterium and inject their genes. This viral DNA makes the bacterium churn out new copies of the phages, as well as an enzyme that destroys the bacterium's cell wall so that the phages can spread to other bacteria.

While some scientists are trying to use phages to control bacterial infections (SN: 6/3/00, p. 358), Vincent A. Fischetti of the Rockefeller University in New York and his colleagues have turned to the wall-destroying enzyme itself. They've purified the protein, known as lysin, from the debris of phage-infected Streptococcus pyogenes and have shown that the enzyme alone can destroy bacteria in laboratory dishes.

The investigators have also coated the throats of mice with a solution of lysin and found that it prevents Streptococcus bacteria from establishing an infection. The enzyme had no apparent effect on the harmless bacteria that normally inhabit the rodent throat, adds Rockefeller's Daniel C. Nelson.