Development of an enzyme immunoassay to detect antibody to Chlamydia Pneumoniae strain twar and its application in a limited seroepidemiological survey

A non-competitive enzyme immunoassay (EIA) was developed to detect IgG antibody to the recently-described species Chlamydia pneumoniae strain TWAR. Purified elementary bodies of the organism were used as capture antigen. Cross-reacting antibody to Chlamydia trachomatis was detected in the assay by running a parallel EIA for IgG antibody to C. trachomatis. The C. pneumoniae assay was validated by comparing the results on 60 selected sera with those obtained with the micro-immunofluorescence test. The comparison indicated that the EIA had a sensitivity of 88%, specificity of 100% and overall correlation with micro-immunofluorescence of 93%. The assay was applied to 352 sera from 3 populations within Australasia in a limited survey to determine the extent of exposure to this organism. Prevalence rates of up to 55% were found, suggesting that a significant amount of respiratory disease in the region may be due to C. pneumoniae strain TWAR.