title: Quantification of Mannheimia haemolytica leukotoxin by indirect ELISA.
abstract: An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of extracellular leukotoxin (LKT) produced in chemostat culture of Mannheimia haemolytica in a serum-free culture medium. Leukotoxin purified with preparative SDS-PAGE was used for the production of chicken polyclonal antibodies (PAb) that served as the primary detecting antibody. Excising the LKT protein from an analytical SDS-PAGE gel proved an efficient technique for the purification of the toxin. Consequently, the 102 kDa LKT polypeptide purified in this manner served as reference toxin and the resulting calibration curve was modelled using a four parameter logistic fit to relate absorbance to LKT protein concentration. The lower detection limit corresponded to an LKT concentration of 14.5 ng ml(-1). The presence of SDS, serum albumin and the coating pH had a distinct effect on the absorbance values of the indirect ELISA.
authors.affiliation: Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa.
authors.forename: E
authors.initials: E
authors.lastname: Van Rensburg
authors.forename: J C
authors.initials: JC
authors.lastname: Du Preez
authors.forename: C E
authors.initials: CE
authors.lastname: Ellis
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002417:Cattle; D002645:Chickens; D016895:Culture Media, Serum-Free; D003603:Cytotoxins / Q000096:biosynthesis / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards / Q000662:veterinary*; D005098:Exotoxins / Q000096:biosynthesis / Q000302:isolation & purification*; D016978:Mannheimia haemolytica / Q000254:growth & development / Q000378:metabolism*; D010326:Pasteurella Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary; D012016:Reference Values; D012680:Sensitivity and Specificity; D012756:Sheep
chemical_list: D000911:Antibodies, Monoclonal; D016895:Culture Media, Serum-Free; D003603:Cytotoxins; D005098:Exotoxins; C018579:leukotoxin