Modification of the microimmunofluorescence test to provide a routine serodiagnostic test for chlamydial infection

A modification of the microimmunofluorescence test to provide a practicable routine serodiagnostic test for detecting and characterising chlamydial infection is described which uses four antigen pools, one of which corresponds with each of the four main clinical and epidemiological types of chlamydial infection. The three subgroup A Chlamydia (Chlamydia trachomatis) pools are: pool 1, hyperendemic trachoma TRIC agent serotypes A, B, and C; pool 2, paratrachoma TRIC agent serotypes D, E, F, G, H, I, and K; pool 3, lymphogranuloma venereum (LGV) agent serotypes L1, L2, and L3. Pool 4 contained four representative isolates of subgroup B Chlamydia (Chlamydia psittaci). For routine purposes sera need be screened only against these four representative antigen pools. This will detect antibody and indicate which clinical and epidemiological type of chlamydial infection is implicated, thereby clearly distinguishing those infections that are due to C. psittaci. The pattern of the cross-reactions may indicate the individual serotype involved, and further titration requiring a maximum of four individual antigens is sufficient to determine the serotype. The slight loss in sensitivity (twofold) is more than compensated for by the reduction in cost and the tenfold increase in the total number of sera which can be examined.