RESUMO
The respiratory tract is constantly exposed to various airborne pathogens. Most vaccines against respiratory infections are designed for the parenteral routes of administration; consequently, they provide relatively minimal protection in the respiratory tract. A vaccination strategy that aims to induce the protective mucosal immune responses in the airway is urgently needed. The FcRn mediates IgG Ab transport across the epithelial cells lining the respiratory tract. By mimicking this natural IgG transfer, we tested whether FcRn delivers vaccine Ags to induce a protective immunity to respiratory infections. In this study, we designed a monomeric IgG Fc fused to influenza virus hemagglutinin (HA) Ag with a trimerization domain. The soluble trimeric HA-Fc were characterized by their binding with conformation-dependent HA Abs or FcRn. In wild-type, but not FcRn knockout, mice, intranasal immunization with HA-Fc plus CpG adjuvant conferred significant protection against lethal intranasal challenge with influenza A/PR/8/34 virus. Further, mice immunized with a mutant HA-Fc lacking FcRn binding sites or HA alone succumbed to lethal infection. Protection was attributed to high levels of neutralizing Abs, robust and long-lasting B and T cell responses, the presence of lung-resident memory T cells and bone marrow plasma cells, and a remarkable reduction of virus-induced lung inflammation. Our results demonstrate for the first time, to our knowledge, that FcRn can effectively deliver a trimeric viral vaccine Ag in the respiratory tract and elicit potent protection against respiratory infection. This study further supports a view that FcRn-mediated mucosal immunization is a platform for vaccine delivery against common respiratory pathogens.
Assuntos
Antígenos de Histocompatibilidade Classe I/metabolismo , Vacinas contra Influenza/imunologia , Influenza Humana/imunologia , Infecções por Orthomyxoviridae/imunologia , Orthomyxoviridae/fisiologia , Receptores Fc/metabolismo , Mucosa Respiratória/metabolismo , Administração Intranasal , Animais , Anticorpos Antivirais/metabolismo , Modelos Animais de Doenças , Resistência à Doença , Feminino , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Antígenos de Histocompatibilidade Classe I/genética , Humanos , Fragmentos Fc das Imunoglobulinas/genética , Imunoglobulina G/metabolismo , Vacinas contra Influenza/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Fc/genética , Mucosa Respiratória/imunologia , VacinaçãoRESUMO
Human cytomegalovirus (HCMV) can persistently infect humans, but how HCMV avoids humoral immunity is not clear. The neonatal Fc receptor (FcRn) controls IgG transport from the mother to the fetus and prolongs IgG half-life. Here we show that US11 inhibits the assembly of FcRn with ß2m and retains FcRn in the endoplasmic reticulum (ER), consequently blocking FcRn trafficking to the endosome. Furthermore, US11 recruits the ubiquitin enzymes Derlin-1, TMEM129 and UbE2J2 to engage FcRn, consequently initiating the dislocation of FcRn from the ER to the cytosol and facilitating its degradation. Importantly, US11 inhibits IgG-FcRn binding, resulting in a reduction of IgG transcytosis across intestinal or placental epithelial cells and IgG degradation in endothelial cells. Hence, these results identify the mechanism by which HCMV infection exploits an ER-associated degradation pathway through US11 to disable FcRn functions. These results have implications for vaccine development and immune surveillance.
Assuntos
Infecções por Citomegalovirus/imunologia , Citomegalovirus/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Evasão da Resposta Imune , Imunidade Humoral , Proteínas de Ligação a RNA/metabolismo , Receptores Fc/metabolismo , Proteínas Virais/metabolismo , Linhagem Celular , Citomegalovirus/patogenicidade , Infecções por Citomegalovirus/virologia , Degradação Associada com o Retículo Endoplasmático/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutagênese Sítio-Dirigida , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Receptores Fc/imunologia , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Virais/genética , Proteínas Virais/imunologiaRESUMO
The viral determinants governing the varied neuropathogenicity of different West Nile virus (WNV) strains are poorly understood. Here, we generated an infectious clone (WNV-MAD(IC)) of the non-pathogenic strain WNV-MAD78 and compared its replication to that of parental WNV-MAD78 and a WNV-MAD78 infectious clone (WNV-MAD(TX-UTRs)) containing the 5' and 3' untranslated regions (UTRs) of the pathogenic strain WNV-TX. All three viruses replicated at similar rates and caused similar lethality in mice. Thus, the infectious clone is indistinguishable from parental virus in replication and neurovirulence, and the UTRs alone do not account for the increased virulence of WNV-TX compared to WNV-MAD78.
