Human papillomavirus type 33 L1 capsid protein (HPV33 L1)

The Human papillomavirus type 33 L1 capsid protein (HPV33 L1) is the primary structural component of the HPV type 33 virion, a high-risk viral type associated with the development of cervical, vulvar, and anal cancers [6, 7]. This protein possesses the unique ability to spontaneously self-assemble into virus-like particles (VLPs) that are morphologically and immunologically indistinguishable from the native virus, though they lack viral DNA and are thus non-infectious [1, 9, 11]. Biologically, the L1 protein facilitates initial infection by binding to heparan sulfate proteoglycans on the cell surface of basal keratinocytes, which triggers a conformational change allowing for viral entry via endocytosis [1, 2]. Because of its critical role in viral entry and its high immunogenicity, the L1 protein is the principal antigen in prophylactic human papillomavirus vaccines [11]. Specifically, HPV 33 L1 is a component of the 9-valent HPV vaccine (Gardasil 9), where it induces the production of neutralizing antibodies [3, 12]. These antibodies prevent future infections by blocking the virus from attaching to host cells, although the vaccine does not provide therapeutic benefit for individuals already infected with the virus [8, 12].

Other names

Major capsid protein L1Late protein L1HPV33 L1 proteinHuman papillomavirus 33 L1 capsid proteinHPV type 33 L1

The vaccine induces a humoral immune response by stimulating the production of high titers of neutralizing IgG antibodies that bind to the L1 protein on the viral surface, thereby preventing viral attachment and entry into host cells [3, 8].