Bor·det \bȯr-dā\ Jules–Jean–Baptiste–Vincent (1870–1961), Belgian bacteriologist, and Gen·gou \zhaⁿ-gü\ Octave (1875–1957), French bacteriologist. Bordet was an outstanding immunologist. His discovery of the role of antibodies and complement in immunity was a development vital to the modern diagnosis and treatment of many dangerous contagious diseases. His research on the destruction of bacteria and foreign red corpuscles in blood serum is generally held to constitute the beginnings of serology. In 1901 he and Gengou published the first of their reports on complement fixation. This reaction is the basis of many tests for infection, including the Wassermann test for syphilis and reactions for gonococcus infection, glanders, and hydatid disease. In 1906 they discovered the causative agent of whooping cough, now known as the Bordet-Gengou bacillus. Bordet was awarded the Nobel Prize for Physiology or Medicine in 1919.