Structural and Functional Properties of Yersinia pestis Caf1 Capsular Antigen and Their Possible Role in Fulminant Development of Primary Pneumonic Plague

Yersinia pestis capsular antigen Caf1 is shown to be a β-structural protein that in polymeric form possesses very high conformational stability. Different approaches show that a dimer is the minimal cooperative block of Caf1 adhesin. Caf1 dimer interacts effectively with IL-1 receptors of human macrophage and epithelial cells. The specificity of such interaction is confirmed by the inhibition of IL-1α binding by Caf1. The Caf1 role in pneumonic plague pathogenesis is discussed.