Study of the Surface Antigenic Determinants of <i>Vibrio cholerae</i> Strains with Atypical Agglutinability Using the Panel of Monoclonal Antibodies

Abstract

The aim of the work was to study surface antigenic determinants of V. cholerae R-variant strains using enzyme immunoassay and a panel of monoclonal antibodies (MAbs).Materials and methods. 60 strains of V. cholerae R-variant isolated from ambient environment objects in the territories of the former USSR and the constituent entities of the Russian Federation over a 30-year period (1988–2019) were investigated in the slide agglutination reaction with cholera diagnostic sera, enzyme immunoassay (ELISA) using the panel of MAbs specific to membrane proteins and a set of reagents “Monoclonal diagnostic immunoglobulins labeled with horseradish peroxidase, dry, for serological identification of V. cholerae O1 and O139 (in vitro) through ELISA and dot-ELISA”.Results and discussion. The analysis of the surface structures of V. cholerae R-variant strains with atypical agglutinability has been carried out applying enzyme immunoassay. It showed that individual strains with different amounts of O-antigen are registered among the studied strains identified at isolation as V. cholerae R-variant (the optical density range is from 0.261±0.002 to 1.312±0.003). Epitopes of specific O-antigen were found in some “conservative” strains (30 %) that are agglutinated only with RO serum, and in several strains (20 %) that do not have the wbeT gene that determines its synthesis, and lost agglutinability with all diagnostic cholera sera, including RO. The protein epitopes recognized by complementary MAbs are represented with varying frequency in the composition of surface antigens of R-vibrios; a decrease in their representation or absence on the cell surface correlates with the modification or loss of R-LPS and is accompanied by a negative agglutination reaction.