Common Antigens between Adult Schistosoma mansoni and the Laboratory Mouse

Abstract

Common antigens are shown to exist between adult Schistosoma mansoni and a host, the albino mouse. The Ouchterlony technique, in which anti-schistosome rabbit sera are used to compare schistosome extract and mouse serum test antigens, reveals at least four common antigens. Furthermore, rabbit antisera prepared against whole worm homogenates are able to agglutinate mouse erythrocytes. Finally, anti-schistosome sera are found to contain increased levels of sheep hemolysins, indicative of the Forssman antigen in the worm. The Forssman antigen is also known to be present in the mouse, making it another shared antigen. The origins of the common antigens in the worm are still unknown. This report describes a number of immunological cross-reactivities which exist between adult Schistosoma mansoni and a laboratory host, the white mouse. Such cross-reactivities are due to what may be called common or shared antigens; and by these terms absolutely nothing should be inferred about the nature and origin of the antigens involved beyond the simple experimental demonstration that such common antigens exist. With further critical work, common antigens may be classified as either contaminating or eclipsed antigens, the distinction being in their genetic origin (Damian, 1964). Whatever the case may be, the origin of the antigen in question should be known. In the first place, the presence of contaminating antigens of host (or culture medium) origin would appear to be relevant to any thorough description of the antigenic composition of a parasitic organism. The practical importance of this was recognized by Kagan et al. (1960), who suggested that such contaminants in serologic antigens prepared from parasites could lead to nonspecific (false-positive) reactions in serodiagnosis. This suggestion was substantiated in later work from Kagan's laboratory Received for publication 29 July 1966. * The major part of this report is from a dissertation submitted in partial fulfillment of the requirements of the Ph.D. degree at Florida State University. This investigation was carried out in part during the tenure of Predoctoral Fellowships from the NIAID and the Division of General Medical Sciences, U. S. Public Health Service. Support in part was also provided by Public Health Service Research grant AI-06298 from the NIAID. t Present address. (Kagan and Norman, 1963). If the common antigen is shown to be an eclipsed antigen, the fact has possible significance for certain aspects of the host-parasite relationship (Dineen, 1963; Damian, 1964). COMMON ANTIGENS REVEALED BY IMMUNODIFFUSION ANALYSIS Materials and Methods The Ouchterlony technique and the reagents used were described earlier (Damian, 1966). Briefly, Schistosoma mansoni saline extracts (SMSE) were used as test antigens for immunodiffusion analysis. Antisera were obtained from rabbits initially injected into the toe pads with whole worm homogenates in Freund incomplete adjuvant (Difco) followed by intravenous booster injections. Adult males and females were used for both of these preparations. In addition, mouse serum test antigen (MS) was obtained and pooled rom uninfected albino mice bled by decapitation. TABLE I. Number of bands between mouse serum and rabbit control and anti-schistosome sera.