RESUMEN
There is a great need for the development of vaccines that induce potent and long-lasting protective immunity against SARS-CoV-2. Multimeric display of the antigen combined with potent adjuvant can enhance the potency and longevity of the antibody response. The receptor binding domain (RBD) of the spike protein is a primary target of neutralizing antibodies. Here, we developed a trimeric form of the RBD and show that it induces a potent neutralizing antibody response against live virus with diverse effector functions and provides protection against SARS-CoV-2 challenge in mice and rhesus macaques. The trimeric form induces higher neutralizing antibody titer compared to monomer with as low as 1µg antigen dose. In mice, adjuvanting the protein with a TLR7/8 agonist formulation alum-3M-052 induces 100-fold higher neutralizing antibody titer and superior protection from infection compared to alum. SARS-CoV-2 infection causes significant loss of innate cells and pathology in the lung, and vaccination protects from changes in innate cells and lung pathology. These results demonstrate RBD trimer protein as a suitable candidate for vaccine against SARS-CoV-2.
Asunto(s)
Adyuvantes Inmunológicos/administración & dosificación , Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , COVID-19/prevención & control , Compuestos Heterocíclicos con 3 Anillos/administración & dosificación , Ácidos Esteáricos/administración & dosificación , Compuestos de Alumbre/administración & dosificación , Enzima Convertidora de Angiotensina 2/inmunología , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Formación de Anticuerpos/inmunología , Vacunas contra la COVID-19/administración & dosificación , Modelos Animales de Enfermedad , Compuestos Heterocíclicos con 3 Anillos/inmunología , Humanos , Macaca mulatta , Ratones , Unión Proteica , SARS-CoV-2/aislamiento & purificación , Glicoproteína de la Espiga del Coronavirus/inmunología , Ácidos Esteáricos/inmunologíaRESUMEN
To increase vaccine immunogenicity, modern vaccines incorporate adjuvants, which serve to enhance immune cross-protection, improve humoral and cell-mediated immunity, and promote antigen dose sparing. Pattern recognition receptors (PRRs), including the Toll-like receptor (TLR) family are promising targets for development of agonist formulations for use as vaccine adjuvants. Combinations of co-delivered TLR4 and TLR7/8 ligands have been demonstrated to have synergistic effects on innate and adaptive immune response. Here, we create liposomes that stably co-encapsulate CRX-601, a synthetic TLR4 agonist, and UM-3004, a lipidated TLR7/8 agonist, within the liposomal bilayer in order to achieve co-delivery, allow tunable physical properties, and induce in vitro and in vivo immune synergy. Co-encapsulation demonstrates a synergistic increase in IL-12p70 cytokine output in vitro from treated human peripheral blood mononuclear cells (hPBMCs). Further, co-encapsulated formulations give significant improvement of early IgG2a antibody titers in BALB/c mice following primary vaccination when compared to single agonist or dual agonists delivered in separate liposomes. This work demonstrates that co-encapsulation of TLR4 and lipidated TLR7/8 agonists within the liposomal bilayer leads to innate and adaptive immune synergy which biases a Th1 immune response. Thus, liposomal co-encapsulation may be a useful and flexible tool for vaccine adjuvant formulation containing multiple TLR agonists.
Asunto(s)
Adyuvantes Inmunológicos/administración & dosificación , Compuestos Heterocíclicos con 3 Anillos/administración & dosificación , Inmunidad Humoral/inmunología , Monosacáridos/administración & dosificación , Vacunas/administración & dosificación , Animales , Sistemas de Liberación de Medicamentos , Sinergismo Farmacológico , Femenino , Compuestos Heterocíclicos con 3 Anillos/inmunología , Compuestos Heterocíclicos con 3 Anillos/farmacología , Humanos , Leucocitos Mononucleares/inmunología , Liposomas , Ratones , Ratones Endogámicos BALB C , Monosacáridos/inmunología , Monosacáridos/farmacología , Células TH1/inmunología , Receptor Toll-Like 4/agonistas , Receptor Toll-Like 7/agonistas , Receptor Toll-Like 8/agonistas , Vacunas/inmunologíaRESUMEN
Antibodies and cytotoxic T cells represent 2 arms of host defense against pathogens. We hypothesized that vaccines that induce both high-magnitude CD8+ T cell responses and antibody responses might confer enhanced protection against HIV. To test this hypothesis, we immunized 3 groups of nonhuman primates: (a) Group 1, which includes sequential immunization regimen involving heterologous viral vectors (HVVs) comprising vesicular stomatitis virus, vaccinia virus, and adenovirus serotype 5-expressing SIVmac239 Gag; (b) Group 2, which includes immunization with a clade C HIV-1 envelope (Env) gp140 protein adjuvanted with nanoparticles containing a TLR7/8 agonist (3M-052); and (c) Group 3, which includes a combination of both regimens. Immunization with HVVs induced very high-magnitude Gag-specific CD8+ T cell responses in blood and tissue-resident CD8+ memory T cells in vaginal mucosa. Immunization with 3M-052 adjuvanted Env protein induced robust and persistent antibody responses and long-lasting innate responses. Despite similar antibody titers in Groups 2 and 3, there was enhanced protection in the younger animals in Group 3, against intravaginal infection with a heterologous SHIV strain. This protection correlated with the magnitude of the serum and vaginal Env-specific antibody titers on the day of challenge. Thus, vaccination strategies that induce both CD8+ T cell and antibody responses can confer enhanced protection against infection.