Poliovirus capsid protein (D-antigenic conformation) (PV D-antigen)

The poliovirus capsid is an icosahedral shell composed of 60 subunits, each containing the structural proteins VP1, VP2, VP3, and VP4. The D-antigenic conformation refers to the native, mature, and infectious state of the virus particle, which is characterized by the presence of specific epitopes that trigger the production of neutralizing antibodies [1][4]. This conformation is the essential component of the Inactivated Poliovirus Vaccine (IPV), where the D-antigen unit (DU) serves as the standard measure of vaccine potency [2]. If the capsid undergoes heat-induced or chemical denaturation, it shifts to the C-antigenic (or H-antigenic) form, which lacks the ability to induce protective immunity. In addition to its role in vaccination, the capsid proteins in their native state are the primary targets for capsid-binding antiviral agents such as pocapavir [3]. These drugs occupy a hydrophobic pocket in the VP1 protein, effectively locking the capsid to prevent the uncoating process and subsequent release of viral RNA into the host cell. Therefore, maintaining or targeting the D-antigenic structure is fundamental to both the prevention and treatment of poliomyelitis.

Other names

Native poliovirus antigenD-antigenN-antigenInfectious poliovirus particlePoliovirus structural proteinsPoliovirus capsid

Vaccines utilize the D-antigenic conformation to induce neutralizing antibodies that prevent viral attachment and entry into host cells [1][2]. Capsid-inhibiting antiviral drugs, such as pocapavir, bind to a hydrophobic pocket within the VP1 protein of the D-antigenic capsid, stabilizing the structure and preventing the conformational changes required for viral uncoating and RNA release [3].