Birth Control Tests Use Bacteria

Salmonella bacteria have been genetically altered to produce an oral birth control vaccine being tested in mice that primes the immune system to reject sperm before conception, a researcher reported Monday.

The vaccine causes a harmless, temporary infection in the intestine that triggers antibodies against genetic components of sperm that have been spliced into the bacteria, said Roy Curtiss of Washington University in St. Louis.

Tests of the contraceptive vaccine have been done only with mice. But the results suggest that a single dose of the vaccine might prevent conception for several months or longer. The effect would be reversible within a year or so, Curtiss said.

The method also might be used to produce a male version of the vaccine, intended to disarm sperm and make men temporarily sterile, Curtiss said at a meeting of the Council for the Advancement of Science Writing.