Poliovirus type 1 capsid protein (PV1 capsid) (PV1 capsid)

The Poliovirus type 1 (PV1) capsid protein complex is an icosahedral assembly of 60 copies each of four structural proteins: VP1, VP2, VP3, and VP4 (UniProt P03300; news-medical.net). This structural unit is responsible for protecting the viral RNA genome and facilitating infection by binding to the host cell receptor CD155 (PVR) through a surface feature known as the "canyon" (nih.gov). Upon receptor binding, the capsid undergoes an irreversible transition to a 135S "A-particle" intermediate, characterized by the externalization of VP4 and the N-terminus of VP1 to form a membrane pore (nih.gov). This process is the critical step for genome translocation into the host cytoplasm (nih.gov). The capsid surface contains critical neutralizing epitopes, organized into four major antigenic sites (AgS1-AgS4), which are the primary targets for the immune response elicited by the Inactivated Poliovirus Vaccine (IPV) and the Oral Poliovirus Vaccine (OPV) (nih.gov). Therapeutic agents such as the capsid inhibitor Pocapavir (V-073) and WIN compounds target these proteins by binding to a hydrophobic pocket in VP1, thereby stabilizing the capsid and preventing the conformational changes required for genome release (nih.gov). Challenges in targeting these structural epitopes include the emergence of drug-resistant mutants and the risk of vaccine-associated paralytic poliomyelitis (VAPP) or circulating vaccine-derived polioviruses (cVDPV) resulting from the use of live-attenuated vaccines (nih.gov; asm.org).

Other names

Poliovirus type 1 structural proteinsVP1VP2VP3VP4Poliovirus type 1 structural epitopesD-antigenAntigenic sites 1-4 (AgS1-AgS4)

Capsid stabilization, Inhibition of viral uncoating, Neutralization of viral infectivity, Prevention of receptor binding