title: Salmonella may offer contraceptive.
abstract: A reversible, inexpensive birth control vaccine for men and women may come from an unlikely source--genetically altered salmonella bacteria.  The bacteria cause food poisoning, typhoid and diarrhea. But with some genes removed and others spliced in, an altered form produces proteins that make the immune system reject sperm and does not cause disease, says Dr. Roy Curtiss, a biology professor at Washington University in St. Louis, Missouri, US.  The approach was announced in November at a US meeting of the Council for the Advancement of Science Writing.  "Salmonella act as the factory, making specific antigens.  It is a slow-release system," he says. The altered bacteria produce sperm antigens, and both male and female immune systems make antibodies against them.  To sustain immunity, a booster vaccine might be necessary every 6 to 12 months.  Numerous concerns, however, have been raised over the use of such live vaccines.  A live vaccine, for example, could accidentally immunize people through fecal contamination of water or food.  Researchers are testing the vaccine approach in mice and are scheduled to begin experiments soon with macaque monkeys and baboons.  Experiments among humans are not yet scheduled and would not begin until ethical and health issues are resolved.  The contraceptive vaccine could be inexpensive to produce and would require no refrigeration, making it easy to store.  It would probably be administered orally, eliminating costs and risks associated with injections, Dr. Curtiss says.
mesh_terms: D000569:Americas; D003267:Contraception; D003269:Contraception, Immunologic; D019049:Developed Countries; D005193:Family Planning Services; D009656:North America; D014481:United States; D022642:Vaccines, Contraceptive
chemical_list: D022642:Vaccines, Contraceptive
keywords: Americas; Contraception; Contraception Research; Contraception, Immunological; Contraceptive Vaccines; Developed Countries; Family Planning; North America; Northern America; United States