Lactoferrin binding properties of Vibrio cholerae.

The lactoferrin binding properties of Vibrio cholerae, a non-invasive pathogen were investigated. Screening of fifty V. cholerae strains of different serogroups and serotypes, showed that 10% of the V. cholerae strains bound to 125I-labelled lactoferrin, and 40% of the 125I-labelled lactoferrin bound to V. cholerae strain 623 could be displaced by unlabelled lactoferrin. Other iron-binding glycoproteins and ferroproteins like ferritin, transferrin, haemoglobin, and myoglobin inhibited the binding of 125I-lactoferrin to a lesser degree. Monosaccharides (GalNac, Man, Gal, and Fuc), and other glycoproteins such as fetuin and orosomucoid also inhibited the binding to a lesser extent. V. cholerae 623 showed a cell surface associated-proteolytic activity which cleaved off the cell-bound 125I-labelled lactoferrin. The generation of cryptotopes on the V. cholerae cell surface by proteolytic digestion favoured the binding of ferritin, transferrin, haemoglobin, and haemin, as well as Congo red, to cells of V. cholerae 623.