Capsid protein VP2 of infectious bursal disease virus (VP2)

Capsid protein VP2 is the major structural and immunogenic protein of infectious bursal disease virus (IBDV), accounting for approximately 51% of the total virion protein and forming the entire outer shell of the icosahedral viral capsid[3][9][8]. VP2 is initially synthesized as a precursor (pVP2 or VPX) and is subsequently processed to its mature form during virus assembly[7][4]. Structural studies reveal that VP2 folds into three main domains: a conserved base, a shell, and a protruding domain, the last of which contains a hypervariable region (HVR; amino acids 206–350) responsible for antigenicity and virulence differences among IBDV strains[3][9][2][6]. VP2 is the primary target of neutralizing antibodies: its surface-exposed loops serve as key epitopes for host immune responses, and antigenic variation in these regions underlies vaccine failures and emergence of new virus variants[9][10]. Mutations in the VP2 HVR modulate virulence, tissue tropism, cellular receptor binding, and susceptibility to neutralizing monoclonal antibodies[3][9]. The protein can also mediate apoptosis in infected host cells by molecular interactions that interfere with antiapoptotic host proteins[4]. VP2 is a major focus of vaccine and diagnostic development due to its central roles in virus structure, infectivity, and immune recognition[9][3][2].

Other names

VP2 proteinMajor capsid protein VP2Viral protein 2

Induction of neutralizing antibody responses (primary immunogen for vaccine development); antigenic mutations in VP2 result in immune escape; structural changes affecting viral infectivity, tissue tropism, and resistance to host immune defenses.