Viral enzyme tackles strep throat

From Los Angeles, at the annual meeting of the American Society for Microbiology

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: Viruses that slay bacteria draw new interest), 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.