ABSTRACT
A universal influenza vaccine that does not require annual reformulation would have clear advantages over the currently approved seasonal vaccine. In this study, we combined the mucosal adjuvant alpha-galactosylceramide (αGalCer) and peptides designed across the highly conserved influenza precursor haemagglutinin (HA(0)) cleavage loop as a vaccine. Peptides designed across the HA(0) of influenza A/H3N2 viruses, delivered to mice via the intranasal route with αGalCer as an adjuvant, provided 100â% protection following H3N2 virus challenge. Similarly, intranasal inoculation of peptides across the HA(0) of influenza A/H5N1 with αGalCer completely protected mice against heterotypic challenge with H3N2 virus. Our data suggest that these peptide vaccines effectively inhibited subsequent influenza A/H3N2 virus replication. In contrast, only 20â% of mice vaccinated with αGalCer-adjuvanted peptides spanning the HA(0) of H5N1 survived homologous viral challenge, possibly because the HA(0) of this virus subtype is cleaved by intracellular furin-like enzymes. Results of these studies demonstrated that HA(0) peptides adjuvanted with αGalCer have the potential to form the basis of a synthetic, intranasal influenza vaccine.
Subject(s)
Hemagglutinin Glycoproteins, Influenza Virus/immunology , Influenza Vaccines/immunology , Adjuvants, Immunologic/administration & dosage , Animals , Body Weight , Cross Protection , Female , Galactosylceramides/administration & dosage , Hemagglutinin Glycoproteins, Influenza Virus/administration & dosage , Histocytochemistry , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/immunology , Influenza A Virus, H5N1 Subtype/genetics , Influenza A Virus, H5N1 Subtype/immunology , Influenza Vaccines/administration & dosage , Lung/pathology , Lung/virology , Mice , Mice, Inbred BALB C , Microscopy , Orthomyxoviridae Infections/pathology , Orthomyxoviridae Infections/prevention & control , Protein Precursors/genetics , Protein Precursors/metabolism , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/immunology , Viral LoadABSTRACT
Four IgG(1kappa) monoclonal antibodies (mAbs) against Influenza A/Chicken/Vietnam/8/2004 (H5N1) virus are described. Three of these showed neutralizing activities against H5N1 strains from clades 1, 2 and 3 using a retroviral pseudotype or live virus microneutralization assay. In the pseudotype assay, the IC(90) neutralizing titre range was >1600-51,200, and with the microneutralization was 80> or =10,240. MAb 1C1 showed strong neutralizing activities in both assays. All four mAbs reacted specifically to the immunogen by immunohistochemical staining and to A/Hong Kong/483/1997 (H5N1) and A/Thailand/1(KAN-1)/2004 (H5N1)-infected MDCK cells by immunofluorescence. ELISA titrations of the mAbs showed specificity for H5N1 haemagglutinin (HA) and no cross-reactivity to 15 other Influenza A subtypes. Only mAbs 1C1 and the non-neutralizing 1F7 reacted with HA(1), the cleaved subunit of HA, by Western blot. These results suggest that the mAbs recognize distinct or overlapping epitopes and will be useful reagents for construction of specific rapid point-of-care assays or for therapeutic use.
