Surface antigens present on vegetative Rhizobium meliloti cells may be diminished or absent when cells are in the bacteroid form

Abstract

The results of fluorescent antibody staining of three Rhizobium meliloti strains using three "strain-cross-reactive" and three "strain-specific" monoclonal antibodies indicated that strain-specific antigens present on surfaces of laboratory-cultured vegetative cells were diminished or absent on surfaces of bacteroid cells extracted from alfalfa nodules formed by the respective strains. In contrast, the monoclonal antibody cross-reactive antigens appeared to be generally conserved during the transition from vegetative cells to bacteroids. These results offer a basis for observed reductions or complete loss of capability of some "strain-specific" monoclonal antibodies developed against vegetative Rhizobium cells to detect the strains in nodule squash material by enzyme-linked immunosorbent assay. Key words: Rhizobium, monoclonal antibody, bacteroid, surface antigen, fluorescent antibody.