Semi-purified elementary body suspensions, prepared or preserved in three different ways, have been compared as to their species-specific CF-activity as revealed both against Bedsonia-negative sera of trachoma patients (of known stage), and against psittacosis-positive sera of men and animals.
Two of these antigens (the SPG-formol-antigen and the SPG-glycerol-antigen) revealed a positive species-specific CF-reaction in 61–100% of the Bedsonia-negative serum samples obtained from trachoma patients, with titres ranging from 1/2 to 1/128.
Various parameters (as percentage proportion of positive reactors, CF-titre, duration of the disease, clinical stage of trachoma, etc.) have been analysed for correlation, and the results obtained with the different antigens are compared with one another.
The most useful of the three antigens, showing a good species-specific CF-reactivity and no anticomplementary activity, was found to be the ‘SPG-formolantigen’. However because of its group-specific reactivity, for detection of species-specific trachoma antibodies in routine, it could be used only with Bedsonia-negative samples of sera. Because of the thermolability of its species-specific component, the SPG-formol-antigen proved to be liable to deterioration.
We have pleasure in thanking to Dr F. B. Gordon for help in procuring bibliography and the viable strain of trachoma virus. We wish to express our thanks also to Mrs R. Šepetavic and to Miss M. Krečo for their technical assistance.