Neuraminidase, a secreted enzyme from
Vibrio cholerae
O1, is considered a virulence factor, because it increases the number of cholera toxin's receptors in the gut. Besides, this protein is widely used in investigations involving sialocompounds, in order to know the role of sialic acid residues in different biologic functions. In this work we compared neuraminidase expression levels in 5
V. cholerae O1 strains from different biotypes and serotypes. The 569B strain (Biotype Classic, Serotype Inaba) had the highest level and with this strain we designed a purification procedure that included: ammonium sulphate precipitation combined with pH of minimum solubility of the protein, gel-filtration chromatography (Sephacryl S-200HR), and finally ion-exchange chromatography (Q-Sepharose FF). This scheme gave us a 30 % of recovery with 98 % purity as determined by gel-filtration in HPLC. Purified neuraminidase was used for the pre-treatment of human sera previous to a hemagglutination- inhibition test with influenza type B virus. The enzyme was effective in the removal of non-specific inhibitors of the sera and it yielded similar results that a standard neuraminidase from a commercial source.