Interaction of Bartonella bacilliformis with human erythrocyte membrane proteins

Intracellular invasion is an important aspect of Carrion's disease caused b y Bartonella bacilliformis. Both the hematic and tissue phases of the disea se involve the initial attachment of the organism to erythrocytes and endot helial cells, respectively. Using two different approaches, preliminary evi dence is provided that B. bacilliformis interacts with multiple surface-exp osed proteins on human erythrocytes. Utilizing Western blot analysis, it wa s demonstrated that the organism binds several biotinylated erythrocyte pro teins with approximate molecular masses of 230, 210, 100, 83 and 44 kDa. Th ere was enhanced Bartonella binding to the 44 kDa protein and binding to a 25 kDa protein following exposure of intact red cells to trypsin. Moreover, there was a complete abrogation of binding to these proteins following exp osure of erythrocytes to sodium metaperiodate oxidation, indicating the sig nificance of carbohydrate moieties in the interactions of Bartonella with t he erythrocyte. In a second approach, similar binding proteins or putative receptors were identified when Bartonella was cc-incubated with isolated me mbrane proteins from red cell ghosts. A comparison of the molecular weights of these putative receptors with known erythrocyte proteins and their immu noreactivity to specific antisera suggested that the 230 and 210 kDa protei ns are the alpha and beta subunits of spectrin; the 100 and 83 kDa proteins are band 3 protein and glycophorin A, respectively; and the 44 and 25 kDa proteins are the respective dimeric and monomeric forms of glycophorin B. C onsistent with this notion was the binding of Bartonella to purified prepar ations of alpha and beta spectrin and glycophorin A/B. (C) 2000 Academic Pr ess.