Isolation of midgut agglutinin of Culex quinquefasciatus ( Diptera , Culicidae)

A Lectin that agglutinates Eschrechia coli (ATCC 25922) , Staphylococcus aureus (ATCC 6538) live bacteria and various mammalian red blood cells (RBCs) was identified in Culex quinquefasciatus midgut extract ( Cqlec) by using human (three groups: A, B, and O, RH+)mouse, rat, guinea-pig, rabbit and goat erythrocytes. With the use of (NH4)2 SO4 fractionation, anion - exchange and GluNA CBr-Sepharose 6B affinity chromatography, C. quinquefasciatus mid gut lectin has been purified to homogeneity. IEF and reducing SDS/PAGE revealed that the isolated mid gut lectin have isoelectric point (PI) of 6.30, and a subunit approximate molecular weight of 34.5 KDa .The highest agglutination activity of crude and isolated Cqlec were detected against both Eschrechia coli cells and rabbit RBCs. Significant differences in hemagglutinin titers and carbohydrate inhibition were detected between sugar fed and blood fed adult female mosquitoes.Overall agglutinin levels were increased following a blood meal feeding and E. coli induction using a hypodermic needle. This study presents the first report on the occurrence of heterogeneous anti rabbit RBC agglutinins in the midgut extracts of C. quinquefasciatus from Al kharj area in Saudi Arabia. The HA of lectins are Ca 2+ independent, heat-resistant, and are strongly inhibited by D(+)-mannose and D(+) glucose followed by N-acetyl-Dglucosamine. Raffinose and N-acetyl-D-manosamine were found to be moderate inhibitors. Non of the lectins were inhibited by galactose , lactose , trehalose or fetuin (1%) but the glycosubstances mucin and laminarin showed strong inhibitition using low concentrations . 2D-NMR spectroscopy revealed a component of the corresponding residue in structure having group regions of resolution spectrum of Man9- GlcNAc2Asn.