Human papillomavirus type 6 major capsid protein L1 (HPV6 L1)

Human papillomavirus type 6 L1 is the major capsid protein (~55 kDa) that self-assembles into pentameric capsomers; 72 capsomers form a T=7 icosahedral, nonenveloped capsid of ~50–55 nm enclosing the dsDNA genome. L1 exposes five surface loop regions (BC, DE, EF, FG, HI) that define conformational epitopes for neutralizing antibodies and mediate initial attachment to host heparan sulfate; these loops harbor most inter-genotype variability and underlie type-specific immunity. L1 can assemble into highly immunogenic VLPs without viral genome and is the basis of licensed prophylactic HPV vaccines. During entry, although much L1 dissociates in endosomes, a fraction of L1 (likely as pentameric capsomeres) remains associated with L2 and viral DNA, contributing to genome stabilization during intracellular trafficking. L1 also interfaces with L2 during co-assembly; mutations in L1 residues at the pentamer lumen that contact L2 reduce L2 incorporation and infectivity, highlighting functionally conserved interaction sites. Structural and biochemical studies specific to HPV6 L1, including crystallographic models and PDB entry 6L31, support its role in HPV6 pathobiology; HPV6 is a leading cause of genital warts and recurrent respiratory papillomatosis.

Other names

HPV-6 L1Major capsid protein L1 (HPV6)L1 capsid protein (HPV type 6)

Vaccine-induced neutralizing antibodies bind conformational epitopes across L1 surface loops (notably DE and FG loops), blocking viral attachment/entry and providing type-specific protection with some cross-protection within related species groups