RESUMEN
Many SARS-CoV-2 neutralizing antibodies (nAbs) lose potency against variants of concern. In this study, we developed 2 strategies to produce mutation-resistant antibodies. First, a yeast library expressing mutant receptor binding domains (RBDs) of the spike protein was utilized to screen for potent nAbs that are least susceptible to viral escape. Among the candidate antibodies, P5-22 displayed ultrahigh potency for virus neutralization as well as an outstanding mutation resistance profile. Additionally, P14-44 and P15-16 were recognized as mutation-resistant antibodies with broad betacoronavirus neutralization properties. P15-16 has only 1 binding hotspot, which is K378 in the RBD of SARS-CoV-2. The crystal structure of the P5-22, P14-44, and RBD ternary complex clarified the unique mechanisms that underlie the excellent mutation resistance profiles of these antibodies. Secondly, polymeric IgG enhanced antibody avidity by eliminating P5-22's only hotspot, residue F486 in the RBD, thereby potently blocking cell entry by mutant viruses. Structural and functional analyses of antibodies screened using both potency assays and the yeast RBD library revealed rare, ultrapotent, mutation-resistant nAbs against SARS-CoV-2.
Asunto(s)
Anticuerpos Antivirales/inmunología , Anticuerpos ampliamente neutralizantes/inmunología , COVID-19/inmunología , COVID-19/virología , SARS-CoV-2/genética , SARS-CoV-2/inmunología , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/genética , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/genética , Afinidad de Anticuerpos , Linfocitos B/inmunología , Sitios de Unión/genética , Sitios de Unión/inmunología , Anticuerpos ampliamente neutralizantes/sangre , Anticuerpos ampliamente neutralizantes/genética , COVID-19/terapia , Clonación Molecular , Modelos Animales de Enfermedad , Humanos , Inmunización Pasiva , Inmunoglobulina G/inmunología , Técnicas In Vitro , Pulmón/virología , Ratones , Ratones Endogámicos BALB C , Mutación , Pruebas de Neutralización , Receptores Virales/inmunología , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/inmunología , Sueroterapia para COVID-19RESUMEN
Through 4 June 2021, COVID-19 has caused over 172.84 million cases of infection and 3.71 million deaths worldwide. Due to its rapid dissemination and high mutation rate, it is essential to develop a vaccine harboring multiple epitopes and efficacious against multiple variants to prevent the immune escape of SARS-CoV-2. An in silico approach based on the viral genome was applied to identify 19 high-immunogenic B-cell epitopes and 499 human leukocyte antigen (HLA)-restricted T-cell epitopes. Thirty multi-epitope peptide vaccines were designed by iNeo-Suite and manufactured by solid-phase synthesis. Docking analysis confirmed stable hydrogen bonds of epitopes with their corresponding HLA alleles. When four peptide candidates derived from the spike protein of SARS-CoV-2 were selected to immunize mice, a significantly larger amount of total IgG in serum, as well as an increase of CD19+ cells in the inguinal lymph nodes, were observed in the peptide-immunized mice compared to the control. The ratios of IFN-γ-secreting lymphocytes in CD4+ or CD8+ T-cells in the peptide-immunized mice were higher than those in the control mice. There were also a larger number of IFN-γ-secreting T-cells in the spleens of peptide-immunized mice. The peptide vaccines in this study successfully elicited antigen-specific humoral and cellular immune responses in mice. To further validate the safety and efficacy of this vaccine, animal studies using a primate model, as well as clinical trials in humans, are required.