Kinetics and immunology of early Ebola virus infection (PREVIREMIX)
Immunology
Final Report Abstract
Ebola virus (species Zaire ebolavirus, EBOV) is a highly pathogenic virus that causes Ebola virus disease (EVD) in humans. Severe EVD is characterized by high levels of virus in blood (viremia) and exacerbated inflammation, which results in poorly effective host immune responses. Our laboratory has previously engaged in clinical studies during EVD epidemics, and we have realized that these studies provide little insight into the mechanisms that mediate immune responses against EBOV, because the patients arrive to the treatment center when they are very sick. PREVIREMIX was born to develop models and methods to study how the virus disseminates from the initial portals of entry to the body, in other words, to study the events that are not visible in human patients because they occur during the incubation period. The proposal was built on three objectives, namely, assess the kinetics of early infection, the mechanisms of virus dissemination, and the importance of the dendritic cell (DC)-T cell cross-talk, which provides a bridge between innate and adaptive immunity. These three objectives were organized in three dedicated work packages. In order to achieve these goals, we proposed to develop two important tools: First, we needed a technology to study the very first steps of virus replication and to identify the initial EBOV target cells. Second, we needed an in vivo system to study the kinetics of infection and dissemination in a human-like environment. We solved the first need with the establishment of PrimeFlow RNA technology to specifically follow virus dissemination in real time. This technology, based on flow cytometric identification of cells harboring viral transcripts, allowed us to identify macrophages and migratory DCs as the very first EBOV target cells. Of note, these infected cells were detected well before the development of any signs of disease in mice. Furthermore, we observed how DCs transported infectious virus from the peripheral tissues to the tissue-draining lymph nodes. These findings underscore a paradox, because the cells that are essential to initiate adaptive immune responses, are also responsible for disseminating the pathogen. To further confirm these results, we corroborated these findings using recombinant EBOV expressing GFP. In order to study the importance of the DC-T cell cross-talk in EBOV pathophysiology we established an ‘avatar’ mouse model. These ‘avatar’ mice harbor DCs and T cells from a particular donor and therefore, allow the evaluation of DC-T cell interactions in a physiologically relevant system. These investigations indicated that, transplantation of infected DCs and T cells alone recapitulated severe disease and death in avatar mice, again pointing out at the important role of DCs on EBOV dissemination. Furthermore, this phenotype was dependent on HLA-TCR interactions suggesting that the signals between DCs and T cells during EBOV infection play an important role in the disease outcome.
Publications
- (2019) Comparative pathogenesis of Ebola virus and Reston virus infection in humanized mice. JCI Insight 4(21):e126070
Escudero-Pérez B, Ruibal P, Rottstegge M, Lüdtke A, Port JR, Hartmann K, Gómez-Medina S, Müller-Guhl J, Nelson EV, Krasemann S, Rodríguez E, Muñoz-Fontela C
(See online at https://doi.org/10.1172/jci.insight.126070) - (2022). Avatar mice underscore the role of the T cell-dendritic cell crosstalk in Ebola virus disease and reveal mechanisms of protection in survivors. J Virol 96(18):e0057422
Rottstegge M, Tipton T, Oestereich L, Ruibal P, Nelson EV, Olal C, Port JR, Seibel J, Pallasch E, Bockholt S, Koundouno FR, Boré JA, Rodríguez E, Escudero-Pérez B, Günther S, Carroll MW, Muñoz-Fontela C
(See online at https://doi.org/10.1128/jvi.00574-22)
