Systems vaccinology of the BNT162b2 mRNA vaccine in humans.
The emergency use authorization of two mRNA vaccines in less than a year since the emergence of SARS-CoV-2 represents a landmark in vaccinology1,2. Yet, how mRNA vaccines stimulate the immune system to elicit protective immune responses is unknown. Here we used a systems vaccinology approach to comprehensively profile the innate and adaptive immune responses of 56 healthy volunteers vaccinated with the Pfizer-BioNTech mRNA vaccine. Vaccination resulted in robust production of neutralizing antibodies (nAbs) against the parent Wuhan strain and, to a lesser extent, the B.1.351 strain, and significant increases in antigen-specific polyfunctional CD4 and CD8 T cells after the second dose. Booster vaccination stimulated a strikingly enhanced innate immune response compared to primary vaccination, evidenced by a greater: (i) frequency of CD14+CD16+ inflammatory monocytes; (ii) concentration of plasma IFN-g; (iii) transcriptional signature of innate antiviral immunity. Consistent with these observations, single-cell transcriptomics analysis demonstrated a ~100-fold increase in the frequency of a myeloid cell cluster, enriched in interferon-response transcription factors (TFs) and reduced in AP-1 TFs, following secondary immunization. Finally, we identified distinct innate pathways associated with CD8 T cell and nAb responses, and show that a monocyte-related signature correlates with the nAb response against the B.1.351 variant strain. Collectively, these data provide insights into immune responses induced by mRNA vaccination and demonstrate its capacity to prime the innate immune system to mount a more potent response following booster immunization.
View details for DOI 10.1038/s41586-021-03791-x
View details for PubMedID 34252919
The immunology of SARS-CoV-2 infections and vaccines.
Seminars in immunology
SARS-CoV-2, the virus that causes COVID-19, emerged in late 2019, and was declared a global pandemic on March 11th 2020. With over 50 million cases and 1.2 million deaths around the world, to date, this pandemic represents the gravest global health crisis of our times. Thus, the race to develop a COVID-19 vaccine is an urgent global imperative. At the time of writing, there are over 165 vaccine candidates being developed, with 33 in various stages of clinical testing. In this review, we discuss emerging insights about the human immune response to SARS-CoV-2, and their implications for vaccine design. We then review emerging knowledge of the immunogenicity of the numerous vaccine candidates that are currently being tested in the clinic and discuss the range of immune defense mechanisms that can be harnessed to develop novel vaccines that confer durable protection against SARS-CoV-2. Finally, we conclude with a discussion of the potential role of a systems vaccinology approach in accelerating the clinical testing of vaccines, to meet the urgent needs posed by the pandemic.
View details for DOI 10.1016/j.smim.2020.101422
View details for PubMedID 33262067
Squalene-based adjuvants stimulate CD8 T cell, but not antibody responses, through a RIPK3-dependent pathway.
The squalene-based oil-in-water emulsion (SE) vaccine adjuvant MF59 has been administered to more than 100 million people in more than 30 countries, in both seasonal and pandemic influenza vaccines. Despite its wide use and efficacy, its mechanisms of action remains unclear. In this study we demonstrate that immunization of mice with MF59 or its mimetic AddaVax (AV) plus soluble antigen results in robust antigen-specific antibody and CD8 T cell responses in lymph nodes and non-lymphoid tissues. Immunization triggered rapid RIPK3-kinase dependent necroptosis in the lymph node which peaked at 6 hours, followed by a sequential wave of apoptosis. Immunization with alum plus antigen did not induce RIPK3 kinase-dependent signaling. RIPK3-dependent signaling induced by MF59 or AV was essential for cross-presentation of antigen to CD8 T cells by Batf3-dependent CD8+ DCs. Consistent with this, RIPK3-kinase deficient or Batf3 deficient mice were impaired in their ability to mount adjuvant-enhanced CD8 T cell responses. However, CD8 T cell responses were unaffected in mice deficient in MLKL, a downstream mediator of necroptosis. Surprisingly, antibody responses were unaffected in RIPK3-kinase or Batf3 deficient mice. In contrast, antibody responses were impaired by in vivo administration of the pan-caspase inhibitor Z-VAD-FMK, but normal in caspase-1 deficient mice, suggesting a contribution from apoptotic caspases, in the induction of antibody responses. These results demonstrate that squalene-based vaccine adjuvants induce antigen-specific CD8 T cell and antibody responses, through RIPK3-dependent and-independent pathways, respectively.
View details for DOI 10.7554/eLife.52687
View details for PubMedID 32515732