Antigenic analysis and ultrastructure of the Rickettsia-like organism isolated from Stellantchasmus falcatus (author's transl)

Abstract

Antigenic relations of SF strain (i. e. rickettsia-like isolate fromStellantchasmus falcatus) to Rickettsia sennetsu and Rickettsia tsutsugamushi were investigated by direct fluorescent antibody technique and fin estructures of the organism grown ill RK-13 cell were observed by electron microscopy.1) Results of direct fluorescent antibody techniqueIn direct immunofluorescence, undiluted labeled antibodies to each of the three agents, which were refined from sera of guinea-pigs injected intracerebrally with those agents respectively and were labeled with fluorescein isothiocyanate, stained only homologous agent.From this result it should be concluded tha t these agent had reciprocally different specific antigens and no cross-reacting ones.2) Results of electron microscopic observationsSF strain was found in cytoplasm cf host cell and seen as short-rod-shaped (about 0.3 to 0.7 micron wide and up to 1.0 micron long) and pleomorphic organism. The organism was enclosed by trilaminar cell wall and trilaminar plasma membrane, and the internal structure was made upof electron dence granular ribosomes and irregular pale patches containing DNA strands. The organisms, singly or in aggregate, were contained in vacuoles of host cell cytoplasm.The presence in vacuole of host cell and the fine structure of SF strain resemble those of Coxiella burnetii, Neorickettsia group (Neorickettsia helminthoeca and Elokomon fluke fever agent) and R. sennetsu, but SF strain is different in kind of vector from Coxiella burnetii and in antigenic structure from R. sennetsu. Although the vector pf SF strain differs from that of Neorickettsia group and antigenic relations between them are not investigated, SF strain may be a unique member of Neorickettsia, because i+ is transmitted by endo-parasite and pathogenic for mouse.