Whooping cough bacteria (Bordetella pertussis, left) and acellular vaccine (right), illustration. B. pertussis is a Gram-negative bacillus (rod-shaped bacteria). It infects the respiratory tract, producing a toxin that paralyses the hair-like cilia that line the respiratory tract and clear mucus from it. To compensate the body coughs. The acellular vaccine contains proteins from the surface of the bacteria, that prime the body’s immune system to recognize the bacteria if infected. Created for Science News Magazine.