Abstract
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.
A combination of vaccination approaches will likely be necessary to fully control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Here, we show that modified vaccinia ...Ankara (MVA) vectors expressing membrane-anchored pre-fusion stabilized spike (MVA/S) but not secreted S1 induced strong neutralizing antibody responses against SARS-CoV-2 in mice. In macaques, the MVA/S vaccination induced strong neutralizing antibodies and CD8+ T cell responses, and conferred protection from SARS-CoV-2 infection and virus replication in the lungs as early as day 2 following intranasal and intratracheal challenge. Single-cell RNA sequencing analysis of lung cells on day 4 after infection revealed that MVA/S vaccination also protected macaques from infection-induced inflammation and B cell abnormalities and lowered induction of interferon-stimulated genes. These results demonstrate that MVA/S vaccination induces neutralizing antibodies and CD8+ T cells in the blood and lungs and is a potential vaccine candidate for SARS-CoV-2.
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•Generated MVA-based COVID-19 vaccine encoding prefusion-stabilized spike (MVA/S)•MVA/S vaccination induces strong nAb response and CD8+ T cell response in macaques•MVA/S vaccine protects macaques from SARS-CoV-2 infection and lung immunopathology•MVA/S vaccine prevents infection-induced inflammation and B cell abnormalities in lungs
Modified vaccinia Ankara (MVA) vector-based vaccines are attractive because of their excellent safety and ability to induce long-lived humoral and cellular immunity in humans. Routhu et al. show that an MVA-based COVID-19 vaccine encoding prefusion-stabilized spike (MVA/S) induces strong neutralizing antibody and CD8+ T cell responses and protects macaques from SARS-CoV2 infection, immunopathology, and infection-induced B cell abnormalities in the lungs.
Abstract
Resident memory T cells (TRM) constitute a recently identified lymphocyte lineage that occupies non-lymphoid tissues (NLT) without recirculating. In murine models, upon antigenic ...rechallenge, TRM trigger antiviral responses in neighboring innate and adaptive immune cells, and recruit immune effectors from circulation. Collectively this is referred to as a ‘sensing and alarm’ function. However, the full range of TRM functions has not been assessed, and non-human primate/human TRM function remains almost entirely uncharacterized. Here we established a prime-boost vaccine modality in rhesus macaques to generate abundant SIV-gag-specific CD8 TRM in the female reproductive tract (FRT) and 14 other NLTs. Upon vaginal challenge with CM9 peptide from the SIV gag protein, CD8 TRM reactivation induced expression of CD69 and granzyme B in SIV-gag specific CD8 T cells throughout the rhesus FRT, in situ proliferation (Ki67 expression), and rapid antiviral and IFN response gene expression in essentially all hematopoietic and non-hematopoietic cells. Upregulation of effector genes in CD8 T cells, CD4 T cells, NK cells, and ILCs peaked at 24h and persisted at 48h. CITE-Seq analysis revealed that mucosal CD4 T cells expressed antiviral genes including HIV restriction factors and had reduced expression of the HIV-co-receptor CCR5. Increased numbers of vaginal T cells, memory B cells, and plasma cells at 24h coincided with increased expression of chemokines and VCAM-1 on endothelial and stromal cells and a concomitant reduction in circulating T and B cells. These data demonstrate that CD8 TRM trigger local activation and the mobilization of innate, cellular, and humoral immune responses to the site of antigen exposure in non-human primates.
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