RESUMEN
Influenza remains a serious public health threat throughout the world. Vaccines and antivirals are available that can provide protection from infection. However, new viral strains emerge continuously because of the plasticity of the influenza genome, which necessitates annual reformulation of vaccine antigens, and resistance to antivirals can appear rapidly and become entrenched in circulating virus populations. In addition, the spread of new pandemic strains is difficult to contain because of the time required to engineer and manufacture effective vaccines. Monoclonal antibodies that target highly conserved viral epitopes might offer an alternative protection paradigm. Herein we describe the isolation of a panel of monoclonal antibodies derived from the IgG(+) memory B cells of healthy, human subjects that recognize a previously unknown conformational epitope within the ectodomain of the influenza matrix 2 protein, M2e. This antibody binding region is highly conserved in influenza A viruses, being present in nearly all strains detected to date, including highly pathogenic viruses that infect primarily birds and swine, and the current 2009 swine-origin H1N1 pandemic strain (S-OIV). Furthermore, these human anti-M2e monoclonal antibodies protect mice from lethal challenges with either H5N1 or H1N1 influenza viruses. These results suggest that viral M2e can elicit broadly cross-reactive and protective antibodies in humans. Accordingly, recombinant forms of these human antibodies may provide useful therapeutic agents to protect against infection from a broad spectrum of influenza A strains.
Asunto(s)
Epítopos/inmunología , Subtipo H5N1 del Virus de la Influenza A/inmunología , Virus de la Influenza A/genética , Virus de la Influenza A/inmunología , Gripe Aviar/inmunología , Animales , Anticuerpos/genética , Anticuerpos/inmunología , Anticuerpos Monoclonales/genética , Anticuerpos Monoclonales/inmunología , Aves , Reacciones Cruzadas/genética , Reacciones Cruzadas/inmunología , Brotes de Enfermedades , Epítopos/genética , Humanos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H5N1 del Virus de la Influenza A/genética , Vacunas contra la Influenza/genética , Vacunas contra la Influenza/inmunología , Gripe Aviar/genética , Gripe Humana/genética , Gripe Humana/inmunología , Gripe Humana/prevención & control , Ratones , Datos de Secuencia MolecularRESUMEN
Amiloride-blockable Na(+) transport, measured as an amiloride-blockable short-circuit current (Am-SCC), is mediated by the epithelial Na(+) channel (ENaC). Am-SCC is not normally present in bullfrog tadpole skin, but when such skin is cultured with corticoids an amiloride-blockable Na transport appears. Prolactin (PRL) inhibits its corticoid-induced development. Using specific PCR primers for adult frog ENaC and RT-PCR, we investigated whether corticoids can induce all three ENaC subunits, and whether this expression of ENaC subunit(s) can be blocked by adding PRL with the corticoids. We found that (1) the sequences of the RT-PCR products obtained using primers for alpha-ENaC were identical between larval and adult skins, (2) the mRNAs for all three ENaC subunits were expressed in larval skin under normal conditions despite no amiloride-blockable Na(+) transport being detectable, (3) all three subunits were expressed in larval skins whether they were cultured with corticoids (amiloride-blockable Na transport present) or with corticoids supplemented with PRL (no amiloride-blockable Na transport present). An antibody against a peptide from the alpha-ENaC of adult bullfrog was localized to the apical cells of both larval and adult skins. Since no amiloride-blockable Na transport exists across larval skin under these conditions, these results suggest that ENaC protein was expressed prior to the onset of transport. ENaC may be in the plasma membrane in an inactivated form or, alternatively, within vesicles waiting to be inserted.