title: Preclinical and clinical development of plant-made virus-like particle vaccine against avian H5N1 influenza.
abstract: The recent swine H1N1 influenza outbreak demonstrated that egg-based vaccine manufacturing has an Achille's heel: its inability to provide a large number of doses quickly. Using a novel manufacturing platform based on transient expression of influenza surface glycoproteins in Nicotiana benthamiana, we have recently demonstrated that a candidate Virus-Like Particle (VLP) vaccine can be generated within 3 weeks of release of sequence information. Herein we report that alum-adjuvanted plant-made VLPs containing the hemagglutinin (HA) protein of H5N1 influenza (A/Indonesia/5/05) can induce cross-reactive antibodies in ferrets. Even low doses of this vaccine prevented pathology and reduced viral loads following heterotypic lethal challenge. We further report on safety and immunogenicity from a Phase I clinical study of the plant-made H5 VLP vaccine in healthy adults 18-60 years of age who received 2 doses 21 days apart of 5, 10 or 20 µg of alum-adjuvanted H5 VLP vaccine or placebo (alum). The vaccine was well tolerated at all doses. Adverse events (AE) were mild-to-moderate and self-limited. Pain at the injection site was the most frequent AE, reported in 70% of vaccinated subjects versus 50% of the placebo recipients. No allergic reactions were reported and the plant-made vaccine did not significantly increase the level of naturally occurring serum antibodies to plant-specific sugar moieties. The immunogenicity of the H5 VLP vaccine was evaluated by Hemagglutination-Inhibition (HI), Single Radial Hemolysis (SRH) and MicroNeutralisation (MN). Results from these three assays were highly correlated and showed similar trends across doses. There was a clear dose-response in all measures of immunogenicity and almost 96% of those in the higher dose groups (2 × 10 or 20 µg) mounted detectable MN responses. Evidence of striking cross-protection in ferrets combined with a good safety profile and promising immunogenicity in humans suggest that plant-based VLP vaccines should be further evaluated for use in pre-pandemic or pandemic situations.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00984945.
authors.affiliation: Medicago Inc, Québec, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Landry
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Ward
authors.forename: Sonia
authors.initials: S
authors.lastname: Trépanier
authors.forename: Emanuele
authors.initials: E
authors.lastname: Montomoli
authors.forename: Michèle
authors.initials: M
authors.lastname: Dargis
authors.forename: Giulia
authors.initials: G
authors.lastname: Lapini
authors.forename: Louis-P
authors.initials: LP
authors.lastname: Vézina
mesh_terms: D000293:Adolescent; D000328:Adult; D004311:Double-Blind Method; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry; D006461:Hemolysis; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry; D007074:Immunoglobulin G / Q000737:chemistry; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000627:therapeutic use; D007251:Influenza, Human / Q000517:prevention & control*; D008875:Middle Aged; D009500:Neutralization Tests; D010919:Placebos; D014026:Nicotiana / Q000378:metabolism; D058425:Vaccines, Virus-Like Particle / Q000627:therapeutic use*
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007074:Immunoglobulin G; D007252:Influenza Vaccines; D010919:Placebos; D058425:Vaccines, Virus-Like Particle; D007073:Immunoglobulin E