Immunological classification of TRIC agents and of some recently isolated LGV agents by the micro-immunofluorescence test.

Chlamydial isolates are conveniently divided on the basis of their ability to produce iodine staining material in their inclusion bodies, into the iodine- positive Subgroup A, which includes the trachoma- inclusion conjunctivitis (TRIC) agents and most isolates from lymphogranuloma venereum (LGV); and the iodine-negative Subgroup B, which includes isolations from psittacosis, ornithosis, and a wide variety of aniimal diseases.