The coronavirus family member, SARS-CoV-2 has been identified as the causal agent for the pandemic viral pneumonia disease, COVID-19. At this time, no vaccine is available to control further dissemination of the disease. We have previously engineered a synthetic DNA vaccine targeting the MERS coronavirus Spike (S) protein, the major surface antigen of coronaviruses, which is currently in clinical study. Here we build on this prior experience to generate a synthetic DNA-based vaccine candidate targeting SARS-CoV-2 S protein. The engineered construct, INO-4800, results in robust expression of the S protein in vitro. Following immunization of mice and guinea pigs with INO-4800 we measure antigen-specific T cell responses, functional antibodies which neutralize the SARS-CoV-2 infection and block Spike protein binding to the ACE2 receptor, and biodistribution of SARS-CoV-2 targeting antibodies to the lungs. This preliminary dataset identifies INO-4800 as a potential COVID-19 vaccine candidate, supporting further translational study.

SUMMARY microRNAs regulate developmental cell fate decisions, tissue homeostasis and oncogenesis in distinct ways relative to proteins. Here, we show that the tumor suppressor microRNA miR-34a is a cell fate determinant in early stage dividing colon cancer stem cells (CCSCs). In pair-cell assays, miR34a distributes at high levels in differentiating progeny, while low levels of miR34a demarcate self renewing CCSCs. Moreover, miR34a loss of function and gain of function alters the balance between self-renewal and differentiation both in vitro and in vivo. Mechanistically, miR34a sequesters Notch1 mRNA to generate a sharp threshold response where a bimodal Notch signal specifies the choice between self-renewal versus differentiation. In contrast, the canonical cell fate determinant Numb regulates Notch levels in a continuously graded manner. Taken together, our findings highlight a unique microRNA regulated mechanism that converts noisy input into a toggle switch for robust cell fate decisions in CCSCs.

Interleukin 33 (IL-33) has emerged as a cytokine that can exhibit pleiotropic properties. Here we examine IL-33 for its immunoadjuvant effects in an HPV-associated cancer immune therapy model in which cell-mediated immunity is critical for protection. It is known that two biologically active forms of IL-33 exist: full-length IL-33 and mature IL-33. The potential ability of both isoforms to act as vaccine adjuvants to influence the CD4 Th1 and CD8 T cell immune responses has not been well defined. We show that both isoforms of IL-33 are capable of enhancing potent antigen (Ag)-specific effector and memory T cell immunity in vivo in a DNA vaccine setting. We also show that while both forms of IL-33 drove robust IFN-γ responses, neither form drove high secretion of IL-4 or any elevation of IgE levels. Moreover, both isoforms augmented vaccine-induced Ag-specific polyfunctional CD4+ and CD8+ T cell responses, with a large proportion of CD8+ T cells undergoing cytolytic plurifunctional degranulation. Therapeutic studies indicated that established TC-1-bearing mice undergo rapid and complete regression after therapeutic vaccination with both IL-33 adjuvant isoforms used in conjunction with an HPV DNA vaccine. Furthermore, using the P14 transgenic mouse model, we show that IL-33 can significantly expand the magnitude of Ag-specific CD8+ T cell responses and elicit bonafide effector-memory CD8+ T cells. Overall, the data suggests the potential use of these two IL-33 isoforms as immunoadjuvant candidates in future vaccination against other pathogens and in the context of anti-tumor immune-based therapy.