Bordetella pertussis (B. Pertussis) is a small, coccobacillus. Coccobacillus are rod-shaped bacteria. Cocco comes from "cocci" meaning spherical shaped and bacillus comes from "bacilli" meaning elongated. B. pertussis, like most pathogenic bacteria, is Gram-negative. Gram-negative bacteria contain a lipopolysaccharide (LPS) layer. The LPS triggers the body's immune response. The immune system senses a cytokine reaction, which is toxic to the body. Because of this, the body initiates the inflammation of the tissues and blood vessels. B. pertussis is non-motile, meaning it doesn't move.