Low doses of flagellin-L2 multimer vaccines protect against challenge with diverse papillomavirus genotypes.
Genetically modified bacterial flagellin (Fla), a Toll-like receptor-5 (TLR5) ligand, was evaluated as a fusion partner for human papillomavirus (HPV) L2-based immunogens in two animal challenge models; either cutaneous inoculation of rabbits with HPV 'quasivirions' containing cottontail rabbit papillomavirus (CRPV) genomes that induce warts, or intra-vaginal inoculation of mice with HPV 'pseudovirions' encapsidating a luciferase reporter plasmid and measurement of bioluminescence to determine infectivity. An Escherichia coli production system was developed for flagellin-L2 (Fla-L2) fusions containing either monomeric HPV-16 L2 a.a. 11(×11-200) or oligomeric L2 comprising a fusion of the a.a. 11-88 peptides of five (Fla∼5×11-88) or eight (Fla∼8×11-88) genital HPV types. Immunogenicity and bioactivity of Fla-L2 constructs were assessed using an in vitro neutralization and cell-based TLR-5 binding assay, respectively. Efficacy was evaluated following active immunization of rabbits or mice administered 3 intramuscular doses of Fla-L2 recombinants without exogenous adjuvant, followed by challenge. In addition, passive immunization studies of naïve rabbits with serial dilutions of pooled immune sera were used to determine End-Point Protection Titers (EPPT) for each formulation against a broader spectrum of HPV quasivirions. Efficacy was assessed for up to 10 weeks on the basis of wart volume induced following challenge and results compared to licensed L1-VLP vaccines (Gardasil and Cervarix). Following active immunization at doses as low as 1 μg, Fla-L2 fusions afforded complete protection against infection (mice) and disease (rabbits) following either homologous or heterologous HPV challenge. Passive immunization with anti-L2 immune sera discriminated between the different vaccine candidates under evaluation, demonstrated the protective role of antibody and suggested the superiority of this oligomeric L2-TLR5 agonist fusion approach compared to L1-based vaccines in its ability to cross-protect against non-vaccine HPV types.
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA. Electronic address: kirill.kalnin@sanofipasteur.com.
Kirill
K
Kalnin
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Timothy
T
Tibbitts
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Yanhua
Y
Yan
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Svetlana
S
Stegalkina
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Lihua
L
Shen
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Victor
V
Costa
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Robert
R
Sabharwal
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Stephen F
SF
Anderson
Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, MD, USA.
Patricia M
PM
Day
Department of Pathology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
Neil
N
Christensen
Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, MD, USA.
John T
JT
Schiller
Department of Pathology, Johns Hopkins University, Baltimore, MD, USA.
Subhashini
S
Jagu
Department of Pathology, Johns Hopkins University, Baltimore, MD, USA.
Richard B S
RB
Roden
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Jeffrey
J
Almond
Discovery, Sanofi Pasteur, 38 Sidney Street, Cambridge, MA, USA.
Harold
H
Kleanthous
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation; D000956:Antigens, Viral / Q000276:immunology*; D056738:Cross Protection; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D005408:Flagellin / Q000276:immunology*; D005838:Genotype; D007116:Immunization, Passive; D051379:Mice; D009500:Neutralization Tests; D027383:Papillomaviridae / Q000145:classification; D053918:Papillomavirus Vaccines / Q000276:immunology*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000276:immunology; D015678:Viral Structural Proteins / Q000276:immunology*
D000914:Antibodies, Viral; D000956:Antigens, Viral; C073507:L2 protein, cottontail rabbit papillomavirus; D053918:Papillomavirus Vaccines; D011993:Recombinant Fusion Proteins; D015678:Viral Structural Proteins; D005408:Flagellin
Cutaneous challenge; HPV; Human papillomavirus; L2; Neutralizing antibody; Prophylactic vaccine; Protective efficacy; Vaginal challenge