Feline calicivirus capsid protein VP1 (VP1) (VP1)

The Feline calicivirus capsid protein VP1 is the primary structural component of the Feline calicivirus (FCV) virion, an icosahedral, non-enveloped virus (UniProt P11297). It is synthesized as a precursor protein that is post-translationally cleaved to form the mature VP1, which assembles into a shell consisting of 180 subunits. The protein is organized into a conserved shell (S) domain and a protruding (P) domain, with the P2 subdomain being the most distal and variable region (Conley et al., 2019). This P2 subdomain is critical for pathogenesis as it contains the binding site for the host cell receptor, feline junctional adhesion molecule A (fJAM-A), and harbors the major neutralizing epitopes (Ossiboff et al., 2010). Because of its role in viral entry and its exposure on the virion surface, VP1 is the primary target for feline calicivirus vaccines. However, the high mutation rate of the FCV genome leads to significant antigenic variation in the VP1 protein, posing a challenge for long-term vaccine efficacy and necessitating the use of broadly cross-reactive vaccine strains (Radford et al., 2007). Therapeutic interventions often focus on inducing antibodies that can neutralize a wide range of these variants by targeting relatively conserved motifs within the P domain.

Other names

Major capsid proteinCapsid protein VP1VP1 proteinCapsid protein precursor

Vaccines and antibodies target the P2 domain of the VP1 protein to block its interaction with the host receptor feline junctional adhesion molecule A (fJAM-A), thereby preventing viral attachment and entry into host cells (Ossiboff et al., 2010; Conley et al., 2019).