Genetic characterristics of the antigenic sites and some binding epitopes for monoclonal antibodies on the glycoprotein of rabies virus isolated in Vietnam, 2015-2019

Abstract

This study aims to describe genetic characterristics of the antigenic sites and some binding epitopes for monoclonal antibodies on the glycoprotein of rabies virus isolated in Vietnam. In the present study, sequences of the ectodomains (which carries the main antigenic sites) of glycoprotein from 14 rabies virus representing for two rabies virus groups circulating in Viet Nam recently were analyzed. Comparing the ectodomain amino acid sequence of the protein G rabies strains in Vietnam and popular vaccine strains, the similarity ranged from 89.7% to 91.4%, signifcantly higher than the cut off of amino acid identity 74% (vaccine cross-neutralization). Furthermore, the conservation of most of the antigenic sites between the rabies virus strains was also found in our study and the popular vaccines strains. The conservation of binding epitopes for several well characterized rabies virusneutralizing Mabs proposed for a replacement of conventional rabies immunoglobulin (RIG) in human PEP was also determined. The results showed that the binding epitopes for Mabs using in the study were highly conserved. The critical amino acid substitutions diminishing or abolishing the binding of these Mabs were not detected. All together, these results collectively demonstrated that the available commercial vaccines are still protective against the rabies
strains circulating in Vietnam and suggest that some certain MAbs can be considered as good candidates for a cocktail Mabs for Passive immunization against rabies in Vietnam.