Secretion both DNA and proteins. It was discovered in "Agrobacterium tumefaciens", which uses this system to introduce the T-DNA portion of the Ti plasmid into the plant host, which in turn causes the affected area to develop into a crown gall (tumor). "Helicobacter pylori" uses a type IV secretion system to deliver CagA into gastric epithelial cells, which is associated with gastric carcinogenesis. "Bordetella pertussis", the causative agent of whooping cough, secretes the pertussis toxin partly through the type IV system. "Legionella pneumophila", the causing agent of legionellosis (Legionnaires' disease) utilizes a type IVB secretion system, known as the icm/dot (intracellular
Riggs' disease Riggs himself. Riggs' disease Riggs' disease, also known as pyorrhea of a toothsocket or gingivitis expulsiva, is a historical term for periodontitis (gum disease), The condition was described as a purulent inflammation of the dental periosteum. It was named after American dentist John Mankey Riggs (1811–1885). Riggs' disease was said to produce the progressive necrosis of the alveoli and looseness of the teeth. The teeth may become very loose and fall out of the sockets. Mark Twain wrote briefly about Riggs' disease in his short essay, "Happy Memories of the Dental Chair", in which he claims to have been examined