Camille Bachelet, France
Institut Imagine Sylvain Latour LabPresenter of 1 Presentation
IDENTIFICATION OF A HOMOZYGOUS EOMES MUTATION IN A PATIENT WITH HIGH SUSCEPTIBILITY TO EBV INFECTION
Abstract
Background and Aims
EOMES is a transcription factor involved in the activation and differentiation of effector CD8 T-lymphocytes and NK-cells (Pearce, 2003). Conditional EOMES-KO mice demonstrated its role in anti-viral immune response (Paley, 2012). We studied a patient with a mutation in EOMES who died from fulminant EBV infection.
Methods
Whole exome sequencing, Immunofluorescence, EMSA, Crispr-Cas9
Results
We investigated a patient born from a consanguineous family presenting with fatal T-cell lymphoproliferation associated with hemophagocytic lymphohistiocytosis following primary EBV infection at the age of 4. Histological staining of lymph node sections revealed high proportions of EBV-infected T-cells. By WES, we identified a homozygous missense mutation, p.346G>S, in the highly conserved T-box domain of EOMES. The G346S EOMES protein was expressed similarly as the wild-type. Using EMSA, we also confirmed that the mutated protein binds DNA as the WT. However, we observed by immunofluorescence that the G346S EOMES accumulated in the nucleus forming aggregates, which were not observed with the WT, suggesting a greater binding of the mutant protein to DNA. Having no material from the patient, we developed a knock-in mouse using CRISP-Cas9 technology mimicking the human mutation. Preliminary analysis showed no phenotypic abnormalities in the CD8 and CD4 T-cell populations. However, NK-cell development was abnormal with an accumulation of mature NK-cells. In vivo studies of the anti-viral response with LCMV are ongoing.
Conclusions
We identified a missense mutation in EOMES in patient with a fatal EBV infection that may explain this severe immunodeficiency. Additional studies are needed to formally establish the deleterious nature of this mutation.