Sabin poliovirus type 3 capsid antigens (Sabin PV3 capsid)

Sabin poliovirus type 3 capsid antigens are the structural proteins (VP1, VP2, VP3, and VP4) that form the icosahedral shell of the attenuated Sabin strain of Poliovirus Type 3. These proteins are responsible for protecting the viral RNA genome and facilitating attachment to the host cell receptor, CD155, which is critical for viral entry and infection (UniProt: P03300; Wikipedia: Poliovirus). In the context of vaccinology, these antigens are the primary components of the Oral Poliovirus Vaccine (OPV) and the Inactivated Poliovirus Vaccine (IPV), designed to elicit a protective immune response. The Sabin type 3 strain is particularly notable for its genetic instability compared to types 1 and 2; a few key mutations in the capsid and 5' untranslated region can lead to a reversion to neurovirulence, causing vaccine-associated paralytic poliomyelitis (VAPP) (PubMed: 16439538). Consequently, these antigens are central to global eradication efforts, which involve transitioning from live-attenuated vaccines to inactivated or novel oral poliovirus vaccines (nOPV3) that are more genetically stable. Therapeutic interventions targeting these antigens include neutralizing antibodies and small-molecule capsid inhibitors like pocavir, which prevent viral uncoating (PubMed: 24744427).

Other names

Poliovirus type 3 (Sabin) structural proteinsSabin 3 capsid proteinsVP1, VP2, VP3, and VP4 of Sabin poliovirus type 3P3/Leon/12a1b capsid antigens

The capsid antigens serve as the primary targets for neutralizing antibodies induced by vaccination. Vaccines containing these antigens (either live-attenuated or inactivated) prime the immune system to recognize the viral shell, preventing the virus from binding to the host CD155 receptor and entering cells (StatPearls, 2023; PubMed: 28235114).