Antigenic characteristics of Leptotrichia buccalis (Fusobacterium fusiforme).

Gustafson, Robert L. (University of Illinois College of Medicine, Chicago) and Arthur V. Kroeger. Antigenic characteristics of Leptotrichia buccalis (Fusobacterium fusiforme). J. Bacteriol. 84:1313-1320. 1962.-Thirty-nine isolates of an oral filamentous organism, usually termed Leptotrichia buccalis Trevisan (Fusobacterium fusiforme), were isolated from materia alba or saliva. The cultural, morphological, and biochemical characteristics were similar to those reported by other investigators. Agglutination reactions were not reproducible with all strains, since spontaneous agglutination frequently occurred. When sonic extracts of nine strains were tested with antisera by precipitin ring tests, some strains cross-reacted extensively. Indirect fluorescent antibody staining reactions revealed significant antigenic differences among fresh isolates. However, strains which had received 12 or more passages on artificial media cross-reacted with one or several heterologous antisera. Currently, the results do not allow classification of L. buccalis into a given number of antigenic types. From the data obtained by the various serological techniques, a tentative picture of the antigenic complex was formulated. The outermost layer of freshly isolated strains appears to be type-specific, and may be lost or altered upon passage on artificial media. Beneath this surface component lie one or more antigens, which may prove to be group antigens shared by several strains of L. buccalis.