Isolation of Antigenically Active Components from Leptospiral Serovar‐Specific Lipopoly‐saccharide Antigen by Alkaline Treatment

Abstract

The serovar-specific main antigen (TM antigen) of Leptospira interrogans serovar canicola, which has lipopolysaccharide properties, was treated with 0.1 N sodium hydroxide. This treatment degraded the antigen into two major antigenic components, one of high and one of low molecular weight. The component with the lower molecular weight (approximately 4,000 daltons) consisted mainly of carbohydrates, having lost almost all of the fatty acid and protein components of the original antigen. Although the substance lacked immunoprecipitable activity, it continued to show serovar-specific inhibitory potency in a radioimmunoassay system as well as in a microscopic immunoagglutination reaction of the organisms. The antigenic activity of the compound was also reduced by periodate oxidation as was that of the TM antigen. A component with the same chemical and physicochemical properties was also produced by alkaline treatment from a different serotype TM antigen (serovar kremastos Kyoto), but it showed no antigenic activity. Leptospiral serovar-specific main (TM) antigen has been extracted from several organisms of different serovars. The TM antigen possesses chemical and physicochemical properties similar to those of the lipopolysaccharide antigens of gram-negative bacteria (1,2, 10, 15, 16). The antigenic activity of TM antigen is destroyed by periodate oxidation (10, 11). A carbohydrate portion demonstrating antigenic activity was isolated from the TM antigen of serovar kremastos Kyoto by formic acid hydrolysis (Y. Kawaoka, M. Naiki, and R. Yanagawa, in preparation) .In this study, TM antigen was treated with mild alkali to cleave the ester bonds, and it was found that this treatment also produced a carbohydrate fragment with antigenic activity.

An Indirect Enzyme‐linked Immunosorbent Assay for the Detection of Leptospira Interrogans Serovar Pomona Antibodies in Bovine Sera

“…The method of antigen production involved extensive digestion with proteinase K. The epitope(s) recognized by the serovarpomona positive sera was therefore composed of either proteinase K-resistant protein, or, some moiety of the lipopolysaccharide (LPS). The specific nature of the antigen suggests that the latter possibility is more likely since many reports have indicated that Leptospira serogroup-specific antigens are composed of LPS (Adler and Faine 1983;Cinco et al 1988;Farrelly et al 1987;Kawaoka et al 1979;On0 et al 1987;Schoone et al 1989;Tsuji et al 1981). In this ELISA, the optimal carbohydrate concentration of the antigen was approximately 0.6 pg/mL.…”

Evaluation of an Enzyme Immunoassay for Diagnosis of Bovine Leptospirosis Caused by Leptospira Interrogans Serovar Hardjo Type Hardjo-Bovis

“…31 Serogroup-specific antigens are composed of LPS 2,10,18, 21,30,33,35,41 and are probably the best antigens for diagnostic purposes because there are less nonspecific reactions. Serogroup cross-reactive antigens are composed of proteins 31 and may be extracted from leptospiral cells with detergents.…”

Characterization of an antigenic oligosaccharide from Leptospira interrogans serovar pomona and its role in immunity

“…Studies by other workers (19,24,30) have reported the isolation of antigenic fragments from leptospiral LPS by acid or alkaline hydrolysis. These fragments ranged in size from 4 to less than 1 kDa.…”

“…Immunization with leptospiral LPS or PS fraction of LPS from L. interrogans serovar copenhageni protected hamsters against homologous lethal challenge (17), suggesting that leptospiral LPS antigens could be used as immunizing agents against leptospirosis. However, the antigenic determinants of leptospiral LPS have not been defined despite extensive investigations using MAbs (1,24) or antigenic fractions of the LPS (19,25,30). The aim of this study was to characterize a fraction of serovar pomona LPS containing a protective epitope(s) and to assay its ability to elicit the production of agglutinating, opsonic antibodies.…”