title: Adjuvant use of the NKT cell agonist alpha-galactosylceramide leads to enhancement of M2-based DNA vaccine immunogenicity and protective immunity against influenza A virus.
abstract: DNA vaccines can induce both humoral and cellular immune responses in animals. However, DNA vaccines suffer from limited vaccine potency due to low immunogenicity. Therefore, different strategies are required for significant improvement of DNA vaccine efficacy such as inclusion of strong adjuvants. The aim of the present study was to investigate the effects of using α-Galactosylceramide (α-GalCer) as an adjuvant to enhance the immune responses induced by a DNA vaccine, encoding influenza A virus matrix protein 2 (M2), against influenza A challenge. BALB/c mice were immunized three times by intramuscular inoculations of DNA vaccine encoding M2 alone or in combination with α-GalCer adjuvant. The adjuvant effect was evaluated by measuring the serum antibody titers, using ELISA, lymphocyte proliferation, using MTT assay as well as Th1 (IFN-γ and IL-12) and Th2 (IL-4) cytokines. The results showed that co-administration of α-GalCer with the vaccine exert protective effects by influencing the magnitude and quality of humoral responses. Adjuvanted DNA-vaccinated mice revealed a higher IgG titer and IgG2a/IgG1 ratio than mice vaccinated with DNA alone. Furthermore, analysis of M2-specific responses revealed that the DNA vaccine triggered predominately IgG1 and IL-4 responses indicating a Th2 bias. The data also showed that α-GalCer is a potent adjuvant for activation of cellular immune responses to DNA vaccine. This was supported by a higher IgG2a/IgG1 ratio, significantly increased IFN-γ and IL-4 production and CD4+ proliferation, compared with mice receiving the DNA vaccine alone, suggesting a mixed Th1/Th2-type cellular immune response with a Th1 bias. The findings of this study indicate that α-GalCer has the potential to be used as a potent adjuvant for a DNA vaccine encoding M2, since it enhances humoral and cellular immune response and improves immune protection against influenza challenge in mice.
authors.affiliation: Department of Influenza and other respiratory viruses, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Fotouhi
authors.affiliation: Department of Microbiology, Golestan University of Medical Sciences, Gorgan, Iran.|Department of Virology, Pasteur Institute of Iran, P.O. Box: 1316943551, Tehran, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Shaffifar
authors.affiliation: Department of Influenza and other respiratory viruses, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Behrokh
authors.initials: B
authors.lastname: Farahmand
authors.affiliation: Department of Pathology, School of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.
authors.forename: Sadegh
authors.initials: S
authors.lastname: Shirian
authors.affiliation: Department of Microbiology, Golestan University of Medical Sciences, Gorgan, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Saeidi
authors.affiliation: Department of Microbiology, Golestan University of Medical Sciences, Gorgan, Iran.
authors.forename: Alijan
authors.initials: A
authors.lastname: Tabarraei
authors.affiliation: Department of Neurology and Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Robert-Koch-Strasse, Münster, Germany.|Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Gorji
authors.affiliation: Department of Influenza and other respiratory viruses, Pasteur Institute of Iran, Tehran, Iran. ghaem_amir@yahoo.com.|Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran. ghaem_amir@yahoo.com.|Department of Virology, Pasteur Institute of Iran, P.O. Box: 1316943551, Tehran, Iran. ghaem_amir@yahoo.com.
authors.forename: Amir
authors.initials: A
authors.lastname: Ghaemi
mesh_terms: D000276:Adjuvants, Immunologic / Q000627:therapeutic use*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D019556:COS Cells; D002460:Cell Line; D049109:Cell Proliferation; D002522:Chlorocebus aethiops; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005699:Galactosylceramides / Q000276:immunology*; D000071497:Immunogenicity, Vaccine / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007371:Interferon-gamma / Q000097:blood / Q000276:immunology; D053765:Interleukin-12 Subunit p35 / Q000097:blood / Q000276:immunology; D015847:Interleukin-4 / Q000097:blood / Q000276:immunology; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D055611:Natural Killer T-Cells / Q000276:immunology*; D009976:Orthomyxoviridae Infections / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*; D014763:Viral Matrix Proteins / Q000235:genetics / Q000276:immunology*; D000086082:Viroporin Proteins
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D005699:Galactosylceramides; D007074:Immunoglobulin G; D007252:Influenza Vaccines; D007371:Interferon-gamma; D053765:Interleukin-12 Subunit p35; D015847:Interleukin-4; D019444:Vaccines, DNA; D014763:Viral Matrix Proteins; C508859:Il12a protein, mouse; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins; C493154:alpha-galactosylceramide