1. Evidence of Burkholderia pseudomallei-specific immunity in patient sera persistently nonreactive by the indirect hemagglutination assay
- Author
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Natasha L. Williams, Jodie L. Morris, Natkunam Ketheesan, Robert Norton, and Patrick N A Harris
- Subjects
Microbiology (medical) ,Male ,Melioidosis ,Burkholderia pseudomallei ,Lymphocyte ,T-Lymphocytes ,Clinical Biochemistry ,Immunology ,Sensitivity and Specificity ,Immunoglobulin G ,Serology ,Microbiology ,Immunoenzyme Techniques ,Antigen ,parasitic diseases ,medicine ,Immunology and Allergy ,Humans ,Clinical Laboratory Immunology ,Cell Proliferation ,Antigens, Bacterial ,biology ,medicine.diagnostic_test ,Hemagglutination Tests ,medicine.disease ,biology.organism_classification ,Antibodies, Bacterial ,body regions ,medicine.anatomical_structure ,Immunoassay ,biology.protein ,Female ,Antibody - Abstract
The indirect hemagglutination assay (IHA) is the most frequently used serological test to confirm exposure toBurkholderia pseudomallei. Patients with culture-confirmed disease often have a nonreactive IHA at presentation and occasionally fail to seroconvert on serial testing. We investigated whether using antigens derived from the cultured isolates of persistently IHA-nonreactive patient sera improved the sensitivity of the IHA. In addition, we assessed the antigen-specific lymphocyte response in this group of patients to a panel ofB. pseudomalleiantigens, including those derived from their own cultured isolates. Eleven patients with culture-proven melioidosis were identified as having persistently IHA-nonreactive sera. A modified IHA using erythrocytes sensitized with patient isolate-derived antigen tested against convalescent-phase serum was performed. The majority (82%) of sera showed a negative (≤1:5) result, one was borderline (1:20), and one was positive at the cutoff value (1:40). IHA-nonreactive sera were also tested by enzyme immunoassay (EIA), with 73% (8/11) demonstrating IgG positivity. In addition, lymphocytes isolated from persistently IHA-nonreactive patient sera demonstrated significantly increased proliferation in response toB. pseudomalleiantigens compared to controls. These studies demonstrate the presence ofB. pseudomallei-specific antibody by EIA andB. pseudomallei-specific lymphocytes in patient sera categorized as persistently nonreactive according to the IHA. New immunoassays are required and should incorporateB. pseudomalleiantigens that are immunoreactive for this subset of IHA-nonreactive patient sera.
- Published
- 2011