**5. Conclusions**

In conclusion, our study demonstrates that exposure to a low dose of NA, identified as barely symptomatic for the 0.5 LD50 NIMP-exposed mice, could disrupt gu<sup>t</sup> microbiota and immune homeostasis and alter emotional behavior in the long-term (Graphical abstract). Further studies are needed in order to decipher the mechanisms linking microbiota, anxietylike behavior and immune cell response, as well as to discriminate more specific middle timepoints. The association between Intestinimonas and anxiety-like behavior requires further investigations to be confirmed. Nevertheless, our results highlight the need to care for all NA victims, even those exposed to low-doses, and to disclose new biomarkers that could be useful for follow-up with NA victims.

**Author Contributions:** Conceptualization, G.D.B. and K.T.; methodology, G.D.B. and K.T.; validation, S.F., S.M., Q.G., C.O., G.D.B. and K.T.; formal analysis, S.M., Q.G. and K.T.; investigation, S.F., S.M., Q.G., R.B. (Rosalie Bel), J.K., A.B., S.C., G.D.B. and K.T.; resources, R.B. (Rachid Baati), C.O., G.D.B. and K.T.; writing—original draft preparation, S.F., S.M., Q.G., C.O., G.D.B. and K.T.; writing—review and editing, S.F., S.M., Q.G., R.B. (Rachid Baati), C.O., G.D.B. and K.T.; supervision, G.D.B. and K.T.; project administration, C.O., G.D.B. and K.T.; funding acquisition, G.D.B. and K.T.; visualization, G.D.B. and K.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the French Ministry of Armed Forces: Direction Générale de l'Armement (DGA) and the Service de Santé des Armées (SSA), gran<sup>t</sup> #PDH-2-NRBC-4-C-4208. The funding sources had no involvement in study design, collection, data analysis or interpretation, or decision to publish.

**Institutional Review Board Statement:** The animal study protocol was approved by the SSA animal ethics committee according to applicable French legislation (Directive 2010/63/UE, decret 2013-118), authorization project AP 281/ARM/IGSSA/SP (25 November 2017) and decision 223/ARM/IGSSA/SP (19 September 2018).

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This work made use of the IRBA biological analysis platforms, supported by the Service de Santé des Armées. We particularly thank Francisca Fargeau and Christine Frederic for their technical support.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
