Characterization of serum antibodies from women immunized with Gardasil: A study of HPV-18 infection of primary human keratinocytes.
The prevalent human papillomaviruses (HPVs) infect human epithelial tissues. Infections by the mucosotropic HPV genotypes cause hyperproliferative ano-genital lesions. Persistent infections by high-risk (HR) HPVs such as HPV-16, HPV-18 and related types can progress to high grade intraepithelial neoplasias and cancers. Prophylactic HPV vaccines are based on DNA-free virus-like particles (VLPs) composed of the major capsid protein L1 of HPV-16, -18, -6 and -11 (Gardasil) or HPV-16 and -18 (Cervarix). Sera from vaccinated animals effectively prevent HPV pseudovirions to infect cell lines and mouse cervical epithelia. Both vaccines have proven to be highly protective in people. HPV pseudovirions are assembled in HEK293TT cells from matched L1 and L2 capsid proteins to encapsidate a reporter gene. Pseudovirions and genuine virions have structural differences and they infect cell lines or primary human keratinocytes (PHKs) with different efficiencies. In this study, we show that sera and isolated IgG from women immunized with Gardasil prevent authentic HPV-18 virions from infecting PHKs, whereas non-immune sera and purified IgG thereof are uniformly ineffective. Using early passage PHKs, neutralization is achieved only if immune sera are added within 2-4h of infection. We attribute the timing effect to a conformational change in HPV virions, thought to occur upon initial binding to heparan sulfate proteoglycans (HSPG) on the cell surface. This interpretation is consistent with the inability of immune IgG bound to or taken up by PHKs to neutralize the virus. Interestingly, the window of neutralization increases to 12-16h in slow growing, late passage PHKs, suggestive of altered cell surface molecules. In vivo, this window might be further lengthened by the time required to activate the normally quiescent basal cells to become susceptible to infection. Our observations help explain the high efficacy of HPV vaccines.
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Hsu-Kun
HK
Wang
Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Qing
Q
Wei
Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Zina
Z
Moldoveanu
Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Warner K
WK
Huh
Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Huong Lan
HL
Vu
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Thomas R
TR
Broker
Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Institute of Immunology and Microbiology, 1st School of Medicine, Charles University, Prague 2 121 08, Czech Republic. Electronic address: mestecky@uab.edu.
Jiri
J
Mestecky
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Electronic address: LTChow@uab.edu.
Louise T
LT
Chow
D057134:Antibodies, Neutralizing / Q000097:blood / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D002478:Cells, Cultured; D005260:Female; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18 / Q000627:therapeutic use*; D052161:Human papillomavirus 18; D006801:Humans; D007106:Immune Sera / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D015603:Keratinocytes / Q000821:virology*; D009500:Neutralization Tests; D030361:Papillomavirus Infections / Q000517:prevention & control
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D019812:Heparan Sulfate Proteoglycans; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D007106:Immune Sera; D007074:Immunoglobulin G
FcRn; HPV antibodies; HPV vaccine; HPV-18 neutralization; Primary human keratinocytes