title: Heterosubtypic neutralizing monoclonal antibodies cross-protective against H5N1 and H1N1 recovered from human IgM+ memory B cells.
abstract: BACKGROUND
  The hemagglutinin (HA) glycoprotein is the principal target of protective humoral immune responses to influenza virus infections but such antibody responses only provide efficient protection against a narrow spectrum of HA antigenic variants within a given virus subtype. Avian influenza viruses such as H5N1 are currently panzootic and pose a pandemic threat. These viruses are antigenically diverse and protective strategies need to cross protect against diverse viral clades. Furthermore, there are 16 different HA subtypes and no certainty the next pandemic will be caused by an H5 subtype, thus it is important to develop prophylactic and therapeutic interventions that provide heterosubtypic protection.
  
  
  RESULTS
  Here we describe a panel of 13 monoclonal antibodies (mAbs) recovered from combinatorial display libraries that were constructed from human IgM(+) memory B cells of recent (seasonal) influenza vaccinees. The mAbs have broad heterosubtypic neutralizing activity against antigenically diverse H1, H2, H5, H6, H8 and H9 influenza subtypes. Restriction to variable heavy chain gene IGHV1-69 in the high affinity mAb panel was associated with binding to a conserved hydrophobic pocket in the stem domain of HA. The most potent antibody (CR6261) was protective in mice when given before and after lethal H5N1 or H1N1 challenge.
  
  
  CONCLUSIONS
  The human monoclonal CR6261 described in this study could be developed for use as a broad spectrum agent for prophylaxis or treatment of human or avian influenza infections without prior strain characterization. Moreover, the CR6261 epitope could be applied in targeted vaccine strategies or in the design of novel antivirals. Finally our approach of screening the IgM(+) memory repertoire could be applied to identify conserved and functionally relevant targets on other rapidly evolving pathogens.
authors.affiliation: Crucell Holland BV, Leiden, The Netherlands.
authors.forename: Mark
authors.initials: M
authors.lastname: Throsby
authors.forename: Edward
authors.initials: E
authors.lastname: van den Brink
authors.forename: Mandy
authors.initials: M
authors.lastname: Jongeneelen
authors.forename: Leo L M
authors.initials: LL
authors.lastname: Poon
authors.forename: Philippe
authors.initials: P
authors.lastname: Alard
authors.forename: Lisette
authors.initials: L
authors.lastname: Cornelissen
authors.forename: Arjen
authors.initials: A
authors.lastname: Bakker
authors.forename: Freek
authors.initials: F
authors.lastname: Cox
authors.forename: Els
authors.initials: E
authors.lastname: van Deventer
authors.forename: Yi
authors.initials: Y
authors.lastname: Guan
authors.forename: Jindrich
authors.initials: J
authors.lastname: Cinatl
authors.forename: Jan
authors.initials: J
authors.lastname: ter Meulen
authors.forename: Ignace
authors.initials: I
authors.lastname: Lasters
authors.forename: Rita
authors.initials: R
authors.lastname: Carsetti
authors.forename: Malik
authors.initials: M
authors.lastname: Peiris
authors.forename: John
authors.initials: J
authors.lastname: de Kruif
authors.forename: Jaap
authors.initials: J
authors.lastname: Goudsmit
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D000914:Antibodies, Viral / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification; D000918:Antibody Specificity / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000821:virology*; D001666:Binding Sites, Antibody; D003429:Cross Reactions; D004285:Dogs; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000276:immunology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007075:Immunoglobulin M / Q000276:immunology*; D007156:Immunologic Memory / Q000276:immunology*; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D051379:Mice; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D019151:Peptide Library; D017434:Protein Structure, Tertiary; D014019:Tissue Donors
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007075:Immunoglobulin M; D019151:Peptide Library