Polypeptides reactive with antibodies eluted from the surface of Babesia bovis-infected erythrocytes

Abstract

A technique was sought that would enable identification of surface-exposed parasite antigens on Babesia bovis-infected erythrocytes (BbIE) that are not detectable by surface-specific immunoprecipitations. Antibodies which bind to the surface of BbIE were recovered from intact cells using a low pH wash procedure. The eluted antibodies were then used in conventional immunoprecipitation assays to identify parasite-synthesized polypeptides carrying epitopes that are exposed on the surface or are cross-reactive with such epitopes. The results of these experiments support our previous data, obtained using a surface-specific immunoprecipitation technique, in the identification of a repertoire of parasite-derived antigens on the surface of infected erythrocytes (Allred et al., 1991). In addition, two polypeptides of M(r) 68,000 and 185,000 were identified which react strongly with the eluted antibodies but which are not detected by surface-immunoprecipitation. These data illustrate the potential of this approach for identification of parasite polypeptides which carry epitopes exposed on, or cross-reactive with exposed epitopes of the infected erythrocyte surface.

Antigenic variation of parasite-derived antigens on the surface of Babesia bovis-infected erythrocytes

“…However, because the parasite population used to initiate infection in that study was not clonal, this may have reflected the genetic diversity and range of antigen variability present in the inoculum rather than actual antigenic variation. We have recently confirmed that the surface of IRBCs is antigenically altered and that the antigens expressed on the surface are isolate specific (1,3,4). Further, we have demonstrated the presence of at least two isolate-specific antigens of parasite origin on the IRBC surface (1, 4).…”

Variable and Variant Protein Multigene Families in Babesia bovis Persistence

“…An unusual aspect of B. bovis biology is the ability of infected erythrocytes to cytoadhere to the capillary and post-capillary endothelium, resulting in sequestration of infected erythrocytes within the microvasculature of several major organs [59,60,61]. This behavior was associated with isolate-specific antigenic changes [62,63] that were identified as parasite-derived proteins [13,64]. Upon closer inspection, these proteins were observed to undergo frequent changes in their immunoreactivity during the course of an ongoing infection [14,65].…”