Human papillomavirus major capsid protein L1 and minor capsid protein L2 (HPV L1/L2)

The L1 and L2 capsid proteins of human papillomavirus (HPV) are the two principal structural proteins forming the viral capsid. L1 is the major capsid protein, assembling into 72 pentamers to create an icosahedral shell that encapsulates the viral DNA. L2 is the minor capsid protein, present in smaller amounts (12-72 molecules per virion), and is critical for encapsidating the viral genome and mediating subsequent entry and trafficking within host cells. L1 self-assembles into virus-like particles (VLPs), which are immunogenic and serve as the basis for current HPV vaccines. Antibodies targeting L1 are type-specific and mediate prevention of infection, while L2 elicits more broadly cross-reactive antibodies, though it is less immunogenic and less exposed on the virion surface. Both proteins are essential for the stability, infectivity, and immune recognition of HPV, with L1 being the primary antigen in prophylactic vaccines, and L2 being investigated for broader vaccine coverage. Their roles in viral entry, immune evasion, and triggering host responses underpin their importance as therapeutic and preventive targets.

Other names

HPV L1HPV L2Papillomavirus L1 proteinPapillomavirus L2 proteinHPV capsid proteins

Induction of neutralizing antibodies against L1 (basis of prophylactic HPV vaccines); Neutralization of viral entry (antibody-mediated, primarily targeting L1; some broad neutralization potential for L2-directed antibodies)