Poliovirus capsid D-antigen epitope

The Poliovirus capsid D-antigen epitope is a conformational structure present on the icosahedral capsid surface of poliovirus, comprising regions from capsid proteins (primarily VP1, VP2, and VP3)[1][3][4][6]. These epitopes represent the sites bound by neutralizing antibodies elicited during infection or immunization. Multiple D-antigen sites contribute to the overall immunogenicity of the virus and are critical for effective vaccine protection; accurate quantification of D-antigen content is therefore a standard measure of IPV potency[4]. High-resolution structural studies have mapped these epitopes to the 'canyon' region of the capsid—a depression encircling each fivefold axis—overlapping the binding site for the cellular receptor CD155/PVR[1][2][5]. Neutralizing antibodies (such as 9H2 or A12) block this interaction, preventing viral entry and infection by steric hindrance or inducing conformational changes in the capsid[1][2][3]. The stability and antigenic conservation of these sites are central to the long-term effectiveness of polio vaccines, though ongoing viral evolution can alter epitope sequences, underscoring the need for monitoring and mapping in vaccine programs[5].

Other names

D-antigen epitopeNeutralizing antigenic site (NAg) epitopePoliovirus capsid antigenic site

Neutralization via antibody binding that blocks receptor (CD155/PVR) interaction; Antibody-induced conformational change interfering with virus infectivity