Humanized mice to test vaccination against influenza virus via dendritic cells.
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Yu, Chun-I, 1975-
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Critical to the development of human vaccines is the availability of in vivo models of the human immune system that permit testing of vaccine efficacy. Here,we used NOD-SCID-β²m-/- immunodeficient mice which, when engrafted with human CD34⁺ hematopoietic progenitors, develop all subsets of human dendritic cells(DCs) and B cells. T cells and their subsets were reconstituted by adoptive transfer. We found myeloid DCs, plasmacytoid DCs and monocytes in the bone marrow, spleen, and peripheral tissues including skin and lungs. To test DC biologyin vivo, we first used live influenza A/PR8/34 (H1N1) virus. Upon intranasal inoculation, all subsets of human antigen presenting cells were activated. Matured DCs were found accumulated in mediastinal lymph nodes. To evaluate the value of these mice for testing human vaccines, humanized mice were immunized with1) ex vivo-generated DCs, 2) seasonal influenza vaccines and 3) protein antigens fused to anti-DC receptor. Upon vaccination with ex vivo-generated DCs pulsed with heat-inactivated influenza virus, mice developed influenza-specific immunity, i.e. influenza-specific immunoglobulins (Igs) in the serum and influenza virus matrix protein 1 (FluM1)-specific CD8⁺ T cells in the blood, spleen and lungs. Influenza-specific Igs were protective as sera from vaccinated mice inhibited influenza virus-induced hemagglutination in vitro and offered passive protection in vivo. Upon vaccination with seasonal influenza vaccines, i.e. live attenuated trivalent vaccine (LAIV) or killed trivalent vaccine (TIV), humanized mice developed both humoral and cellular immunity. Plasma cells differentiation and the secretion of specific Igs were dependent on the reconstitution with CD45RA⁻CD27⁺CD4⁺ central memory T cells. CD8⁺ T cells specific to two influenza antigens, i.e. FluM1 and NS1, were detected in mice vaccinated with LAIV. TIV-vaccinated mice showed the expansion of FluM1, but not NS1, specific CD8⁺ T cells. Antigen-specific CD8⁺ T cells produced IFN-γ and expressed surface CD107a consistent with the acquisition of effector function. Finally, upon vaccination with anti-DC receptor (DCIR)-FluM1 fusion protein and poly I:C as an adjuvant, DCs efficiently cross-presented FluM1 and expanded antigen-specific CD8⁺T cells. Therefore, humanized mice might be valuable model for testing human vaccines against influenza virus.