Immunological and chemical characterization of the extracellular antigens from Corynebacterium vaginale

Abstract

Supernatants from 72-h peptone-starch-dextrose broth cultures of Corynebacterium vaginale contained significant quantities of three extracellular, soluble antigens (ESA). The ESA were concentrated and partially purified by dialysis followed by ammonium sulfate and ethanol precipitation. Diethylaminoethylcellulose columns were used to isolate two of the three ESA. The ESA were shown to be similar to antigens found on whole C. vaginale cells. Absorption studies indicated that the cell antigens are located at, or near, the surface. On the bases of heat stability, resistance to protease treatment, concanavalin A binding activity, and susceptibility to periodate, it appears that all three ESA are polysaccharide or glycoprotein in nature. A number of serological studies have been undertaken to develop a simple method to distinguish Corynebacterium vaginale and other possibly related bacteria, particularly those found as part of the normal flora of the genital tract (4, 10-13). Although the indirect fluorescent-antibody technique is a simple and rapid method for presumptive identification of C. vaginale (13), it lacks the resolving power of the Ouchterlony technique, which has the ability to recognize antigens and antibodies in mixtures and to establish the identity of antigens. Ouchterlony studies indicate that C. vaginale produces three extracellular, soluble antigens (ESA), at least one of which may be useful to distinguish C. vaginale from other possibly related diphtheroid-like bacteria (11). Interest in the potential use of ESA in techniques for characterization and rapid identification of C. vaginale has prompted our efforts to devise methods for their purification. The present report describes isolation of two of the three antigens from cell-free culture supernatants of C. vaginale. In addition, the three ESA were shown to be carbohydrate or glycoprotein in nature and are immunologically similar to antigens found at, or near, the surface of whole C. vaginale cells. The apparent similarities between ESA of C. vaginale and the C-polysaccharide and C-capsular polysaccharide of Streptococcus pneumoniae are discussed. MATERIALS AND METHODS Organisms. The type strain 594 was obtained from the American Type Culture Collection (14018). Media. C. vaginale was isolated and maintained on blood agar plates (Baltimore Biological Laboratory, Cockeysville, Md.), incubated under increased carbon dioxide tension in a candle jar at 37°C. In the first series of experiments, C. vaginale was