Enzyme immunoassay for detection of antibodies against isolated flagella ofLegionella pneumophila

Flagella ofLegionella pneumophila serogroup 1, strain Philadelphia (ATCC 33152), were isolated and used as antigen to detect antibodies by enzyme immunoassay (EIA) in sera of patients with significant titers againstLegionella as determined by the indirect immunofluorescence assay (IFA). Healthy blood donors served as a control group. Whereas the sera of blood donors were negative in both assays, sera of patients showed two patterns of reactivity. Sera with elevated titers againstLegionella pneumophilasero-group 1 orLegionella gormanii in IFA usually demonstrated high titers in EIA. However, high IFA titers againstLegionella bozemanii were associated with low titers in EIA. The data show that flagella protein ofLegionella pneumophila serogroup 1 strain Philadelphia is of limited value for the detection of antibodies againstLegionella other thanLegionella pneumophila serogroup 1, although in vitro studies revealed genus-specific epitopes. This might be due to unpredictable variabilities in the expression of flagella in vivo.