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IN THE hunt for weapons against bacteria that cause disease, doctors have
turned to their age-old adversaries鈥攙iruses.

Vincent Fischetti and his team at Rockefeller University in New York have
isolated an enzyme from a bacteriophage鈥攁 type of virus that infects
bacteria. The enzyme kills Streptococcus pneumoniae, a potentially
dangerous bacterium that lurks in the noses and throats of half the human
population.

Earlier this year, Fischetti鈥檚 team isolated another bacteriophage enzyme
that kills streptococci, which cause sore throats. The same method could also be
used to find enzymes that kill other bacteria. 鈥淓very bacterium has a
bacteriophage system,鈥� Fischetti says.

S. pneumoniae is a significant source of illness and death
worldwide. It can cause problems ranging from ear infections to potentially
deadly diseases like pneumonia and meningitis.

Fischetti鈥檚 team isolated an enzyme called Pal from a bacteriophage that
infects S. pneumoniae. In lab tests, Pal killed 15 strains of S.
pneumoniae within seconds of contact, but didn鈥檛 affect other, harmless
bacteria. The enzyme also proved effective against S. pneumoniae when
applied to the noses of infected mice.

Fischetti is now planning clinical trials to test a nasal spray containing
Pal. He says the spray could be used periodically, say once a week, to keep the
bacterium under control.

鈥淚 think it鈥檚 an exciting opportunity for both prevention and treatment,鈥�
says Cynthia Whitney of the Centers for Disease Control in Atlanta. She says
that the spray might be especially useful in day-care centres and nursing homes,
where infections can spread very quickly from person to person.