title: Plant-made virus-like particle vaccines bearing the hemagglutinin of either seasonal (H1) or avian (H5) influenza have distinct patterns of interaction with human immune cells in vitro.
abstract: The recent emergence of avian influenza strains has fuelled concern about pandemic preparedness since vaccines targeting these viruses are often poorly immunogenic. Weak antibody responses to vaccines have been seen across multiple platforms including plant-made VLPs. To better understand these differences, we compared the in vitro responses of human immune cells exposed to plant-made virus-like particle (VLP) vaccines targeting H1N1 (H1-VLP) and H5N1 (H5-VLP).
  
  
  
  Peripheral blood mononuclear cells (PBMC) from healthy adults were stimulated ex vivo with 2-5µg/mL VLPs bearing the hemagglutinin (HA) of either H1N1 (A/California/7/2009) or H5N1 (A/Indonesia/5/05). VLP-immune cell interactions were characterized by confocal microscopy and flow cytometry 30min after stimulation with dialkylaminostyryl dye-labeled (DiD) VLP. Expression of CD69 and pro-inflammatory cytokines were used to assess innate immune activation 6h after stimulation.
  
  
  
  H1- and H5-VLPs rapidly associated with all subsets of human PBMC but exhibited unique binding preferences and frequencies. The H1-VLP bound to 88.7±1.6% of the CD19+B cells compared to only 21.9±1.8% bound by the H5-VLP. At 6h in culture, CD69 expression on B cells was increased in response to H1-VLP but not H5-VLP (22.79±3.42% vs. 6.15±0.82% respectively: p<0.0001). Both VLPs were rapidly internalized by CD14+monocytes resulting in the induction of pro-inflammatory cytokines (i.e.: IL-8, IL-1β, TNFα and IL-6). However, a higher concentration of the H5-VLP was required to induce a comparable response and the pattern of cytokine production differed between VLP vaccines.
  
  
  
  Plant-made VLP vaccines bearing H1 or H5 rapidly elicit immune activation and cytokine production in human PBMC. Differences in the VLP-immune cell interactions suggest that features of the HA proteins themselves, such as receptor specificity, influence innate immune responses. Although not generally considered for inactivated vaccines, the distribution and characteristics of influenza receptor(s) on the immune cells themselves may contribute to both the strength and pattern of the immune response generated.
authors.affiliation: Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec H3A 2B4, Canada; Research Institute of McGill University Health Centre, Glen Site, 1001 Décarie Boul., Montréal, Québec H4AG 3J1, Canada.
authors.forename: Hilary E
authors.initials: HE
authors.lastname: Hendin
authors.affiliation: Research Institute of McGill University Health Centre, Glen Site, 1001 Décarie Boul., Montréal, Québec H4AG 3J1, Canada; Medicago Inc., 1020 Route de l'Église, Bureau 600, Québec, Québec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pillet
authors.affiliation: Research Institute of McGill University Health Centre, Glen Site, 1001 Décarie Boul., Montréal, Québec H4AG 3J1, Canada.
authors.forename: Amanda N
authors.initials: AN
authors.lastname: Lara
authors.affiliation: Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec H3A 2B4, Canada; Research Institute of McGill University Health Centre, Glen Site, 1001 Décarie Boul., Montréal, Québec H4AG 3J1, Canada.
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Medicago Inc., 1020 Route de l'Église, Bureau 600, Québec, Québec, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Charland
authors.affiliation: Medicago Inc., 1020 Route de l'Église, Bureau 600, Québec, Québec, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Landry
authors.affiliation: Research Institute of McGill University Health Centre, Glen Site, 1001 Décarie Boul., Montréal, Québec H4AG 3J1, Canada. Electronic address: brian.ward@mcgill.ca.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Ward
mesh_terms: D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D037181:Lectins, C-Type / Q000032:analysis; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins / Q000276:immunology; D058425:Vaccines, Virus-Like Particle / Q000276:immunology*; D055815:Young Adult; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D037181:Lectins, C-Type; D011994:Recombinant Proteins; D058425:Vaccines, Virus-Like Particle; D000099192:CD69 Antigens
keywords: Influenza; Innate immunity; Plant-made vaccines; Virus-like particles