Novel Epitopic Region of Glucosyltransferase B from Streptococcus mutans

Abstract

ABSTRACTIn the development of a component vaccine against caries, the catalytic region (CAT) and glucan-binding domain (GBD) of glucosyltransferase B (GtfB) fromStreptococcus mutanshave been employed as target antigens. These regions were adopted as primary targets because they theoretically include epitopes associated with enzyme function. However, their antigenicities have not been fully evaluated. Although there are many reports about successful vaccination using these components, the principle has not yet been put to practical use. For these reasons, we came to doubt the effectiveness of the epitopes in vaccine production and reevaluated the antigenic region of GtfB by usingin silicoanalyses combined within vitroandin vivoexperiments. The results suggested that the ca. 360-amino-acid variable region (VR) in the N terminus of GtfB is more reactive than CAT and GBD. This region isS. mutansand/or GtfB specific, nonconserved among other streptococcal Gtfs, and of unknown function. Immunization using an adenovirus vector-borne DNA vaccine confirmed that VR is an epitope that shows promise for the development of a caries vaccine.