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Grill FJ, Jugler C, Kaleta E, Chen Q, Magee DM, Grys TE, Lake DF. Clinical Laboratory Utility of a Humanized Antibody in Commercially Available Enzyme Immunoassays for Coccidioidomycosis. Microbiol Spectr 2022; 10:e0257322. [PMID: 36121238 PMCID: PMC9602258 DOI: 10.1128/spectrum.02573-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/04/2022] [Indexed: 01/04/2023] Open
Abstract
Coccidioidomycosis, also called valley fever (VF), is a fungal infection with endemicity in desert regions of the western United States as well as certain arid regions of Central and South America. Laboratory-based diagnosis of VF often relies on the composite results from three serologic-based diagnostics, complement fixation, immunodiffusion, and enzyme immunoassay (EIA). EIA is commonly performed in clinical laboratories because results can be obtained in a few hours. Two commercially available EIAs, IMMY clarus Coccidioides antibody and Meridian Premier Coccidioides, look for the presence of anticoccidioidal IgG and IgM in patient sera that are diluted 1:441. Per regulatory requirements, this dilution step must be verified with a dilution step control despite not being provided as a reagent in either FDA-approved EIA kit. Therefore, clinical laboratories collect and reuse patient sera in subsequent tests that had a positive result in a previous test. This is a nonstandard process, reinforcing the need for a consistent and reliable dilution control. Here, we evaluate the performance of a humanized IgG and IgM antibody as a dilution control in both EIA kits. Both humanized IgG and IgM work well in each EIA and meet the appropriate threshold for positivity. IMPORTANCE In southwestern and western regions of the United States, at least half a million diagnostic tests for coccidioidomycosis (valley fever) are run annually. Enzyme immunoassays (EIAs) are blood tests which require precise dilution of patient serum prior to testing. To ensure patient serum is properly diluted, there is a regulatory requirement to ensure the dilution step is accurate. Two FDA-approved EIAs used to aid in the diagnosis of coccidioidomycosis do not contain controls for this dilution step, leaving clinical laboratories with the only option of using previously positive patient sera, which may not react in a reliable or predictable manner. Here, we evaluate a humanized monoclonal antibody against a coccidioidal antigen and its utility as a dilution control in both available commercial EIAs. The use of a humanized monoclonal antibody provides a standardized and well-characterized dilution control for use in serological assays that aid in diagnosis of coccidioidomycosis.
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Affiliation(s)
| | - Collin Jugler
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Erin Kaleta
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Phoenix, Arizona, USA
| | - Qiang Chen
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - D. Mitchell Magee
- Center for Personalized Diagnostics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Thomas E. Grys
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Phoenix, Arizona, USA
| | - Douglas F. Lake
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
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Grill FJ, Grys TE, Grill MF, Roeder A, Blair JE, Lake DF. Development of a Quantitative Antigen Assay to Detect Coccidioidal Chitinase-1 (CTS1) in Human Serum. Open Forum Infect Dis 2021; 8:ofab344. [PMID: 34337097 PMCID: PMC8320284 DOI: 10.1093/ofid/ofab344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/27/2021] [Indexed: 11/13/2022] Open
Abstract
Background Coccidioidomycosis is often diagnosed with a collection of tests that rely on the patient's ability to mount an immune response to the fungus (antibody-based diagnostics), making diagnosis of this infection challenging. Here we present an antigen-based assay that detects and quantifies coccidioidal chitinase-1 (CTS1) in human serum. Methods An inhibition-based enzyme-linked immunoassay (ELISA) was developed that utilizes a monoclonal antibody specific for coccidioidal CTS1. CTS1 was quantified in commercial antigen preparations using recombinant CTS1 as a standard. Sera from 192 individuals from an endemic area were tested, which included 78 patients (40.6%) with proven or probable coccidioidomycosis. Results The quantity of CTS1 in diagnostic commercial antigen preparations from different suppliers varied. CTS1 antigenemia was detected in 87.2% of patients with proven or probable coccidioidomycosis. Specificity was determined to be 96.94% using serum from individuals who reside in the Phoenix, Arizona area who did not have coccidioidomycosis. Levels of CTS1 correlated with low- and high-titer serology from patients with a coccidioidomycosis diagnosis. Conclusions Since the CTS1 inhibition ELISA described in this report does not depend on the host immune response, it is a promising diagnostic tool to aid in diagnosis and disease monitoring of coccidioidomycosis.
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Affiliation(s)
- Francisca J Grill
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Thomas E Grys
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Phoenix, Arizona, USA
| | - Marie F Grill
- Department of Neurology, Mayo Clinic, Phoenix, Arizona, USA
| | - Alexa Roeder
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Janis E Blair
- Division of Infectious Diseases, Mayo Clinic, Phoenix, Arizona, USA
| | - Douglas F Lake
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
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