Identification of protective cell surface proteins in ribosomal fractions from Salmonella typhimurium

Abstract

Cell surface antigen preparations from Salmonella typhimurium SR-11 prepared by either trichloroacetic acid extraction or boiling in sodium dodecyl sulfate were able to protect C3H/HeJ, C3H/HeDub, and A/J mice. Some of the proteins found in these preparations were shown to exist in the protective ribosomal fraction isolated from S. typhimurium SR-11. Passage of ribosomes isolated from S. typhimurium SR-11 and 6707 through a Sepharose 2B column removed the protective immunogen from 6707 ribosomes but did not completely remove it from SR-11 ribosomes. Immunity to salmonella infection in C3H/HeJ mice induced by ribosomal vaccines may be dependent on the presence of cell surface proteins in the ribosomal fraction.

Antibody-producing cell responses to an isolated outer membrane protein and to complexes of this antigen with lipopolysaccharide or with vesicles of phospholipids from Proteus mirabilis

“…Conversely, the Mr 39,000 protein in this LPSprotein mixture was extremely effective in changing not only the strength but also the type of immune response to LPS (from a predominantly IgM to a predominantly IgG response). We also observed the same change in the type of response to P. mirabilis 19 LPS when that antigen was incorporated into phospholipid vesicles (25). Similarly, Hepper et al (14) reported a switch in mice from a predominantly IgM to an IgG response to Salmonella enteritidis LPS when it was contaminated with endotoxin protein (12), which is apparently a mixture of several outer membrane proteins (27).…”

“…The second injection had no apparent effect on either the strength or the kinetics of the IgM responses to this protein. In contrast, the number of IgG antibody-producing cells was greatly increased after the second injection and reached a peak on day 19 (day 5 after the second stimulus). These responses to the Mr 39,000 protein were typical of responses to a thymus-dependent antigen (24).…”

“…Isolation of protein. The Mr 39,000 protein was isolated from purified cell walls of P. mirabilis 19 essentially according to a method described previously (21,22) except that an additional gel filtration step was carried out to remove traces of LPS detectable by gas-liquid chromatography of fatty acids (9). Briefly, 10 g (wet weight) of purified cell walls (22) was extracted with 1% sodium deoxycholate in 200 ml of a buffer consisting of 0.2 M NaCl, 1 mM ethylenediaminetetraacetate, and 10 mm tris(hydroxymethyl)aminomethane hydrochloride, pH 8.0, at 37°C for 45 .min (21).…”

“…The Mr 39,000 protein coupled to tannin-treated SRBC (23) gave similar results, but twice as much protein was needed to produce the same optimal numbers of plaques. Responses to P. mirabilis 19 LPS were measured against LPS coupled to SRBC as previously described (25).…”

“…In this regard, they represent likely candidates for target antigens involved in specific immunological reactions of a host infected with these organisms. Although several reports in the literature have indicated that some of these proteins have defined mitogenic activity for B cells (2,3,5,12,18) and that immune responses to cell surface proteins may play a role in protection against experimental infections with gram-negative bacteria (6,15,19,27), the actual characteristics of the immune responses to outer membrane proteins have not been studied extensively.…”