title: Use of a recombinant Coccidioides immitis complement fixation antigen-chitinase in conventional serological assays.
abstract: The coccidioidal complement fixation (CF) antigen has been cloned previously, and the fusion protein has been expressed in Escherichia coli. The recombinant CF (rCF) antigen was affinity purified by adsorption-desorption to chitin, and its reactivity was studied by using sera containing coccidioidal antibodies. The affinity-purified rCF antigen formed a line of identity with an immunodiffusion (ID) CF reference antigen (coccidioidin) derived from mycelial-phase Coccidioides immitis and was reactive with human, canine, and equine sera containing coccidioidal antibody. The affinity-purified rCF antigen yielded no detectable reaction with Blastomyces of Histoplasma antiserum by ID. The affinity-purified rCF antigen fixed complement with positive human sera and, even when used at lower concentrations, yielded titers comparable to those obtained with the coccidioidin. The reactivity of the affinity-purified rCF antigen was further evaluated by enzyme immunoassay, in which it manifested good sensitivity (96.9%) and specificity (100%) when evaluated with 43 human patients' sera. Thus, the affinity-purified rCF antigen has yielded reactions comparable to those of crude coccidioidal antigens in conventional CF, IDCF, and enzyme immunoassay.
authors.affiliation: Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis 95616, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Johnson
authors.forename: C R
authors.initials: CR
authors.lastname: Zimmermann
authors.forename: D
authors.initials: D
authors.lastname: Pappagianis
mesh_terms: D000818:Animals; D000908:Antibodies, Fungal / Q000097:blood; D000946:Antigens, Fungal / Q000235:genetics; D002688:Chitinases / Q000235:genetics / Q000276:immunology*; D003045:Coccidioides / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D003047:Coccidioidomycosis / Q000175:diagnosis / Q000276:immunology; D003168:Complement Fixation Tests / Q000379:methods* / Q000706:statistics & numerical data; D004285:Dogs; D005069:Evaluation Studies as Topic; D006736:Horses; D006801:Humans; D005779:Immunodiffusion / Q000379:methods / Q000706:statistics & numerical data; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D011994:Recombinant Proteins; D002688:Chitinases