Klebs described organism in stained smears from infected throats. Loeffler noted that the organism remained localized, yet damage occurred systemically. Serum from these animals protected susceptible animals. Elaboration of toxin causes necrosis of neighboring cells. Inflammation results in the classic pseudomembrane which can actually cause mechanical obstruction and suffocation.
Survivors are immune, but can carry and transmit the organisms.
Carraige rates among vaccinated individuals is much lower. Synthesized as a 560 amino acids polypeptide containing a 25-residue signal sequence for secretion. The mature protein has a molecular mass of 58,343-kDa. Its gene has been sequenced and its structure solved by X-ray crystallography. The protein is proteolytically nicked to generate two chains, a 193 residue A chain and a 342 residue B chain.