# Glutamine antagonist DON attenuates chikungunya virus-induced myositis by suppressing inflammatory activation in a murine model

## TL;DR

This study shows that the drug DON reduces muscle inflammation caused by chikungunya virus in mice by suppressing harmful immune responses.

## Contribution

DON selectively targets glutamine metabolism to reduce immunopathology without compromising antiviral immunity in alphavirus infections.

## Key findings

- DON reduced myositis and inflammation in mice despite not lowering viral loads.
- DON depleted innate immune cells and inhibited T cell activation and function.
- Glutaminolysis inhibition separated immunopathology from viral control in alphavirus disease.

## Abstract

Chikungunya virus (CHIKV), an emerging mosquito-borne alphavirus, induces debilitating polyarthralgia and myositis with no licensed specific therapeutic drugs. This study investigates the virological, immunological, and pathological consequences of targeting glycolysis and glutaminolysis during CHIKV infection. In vitro, either glucose/glutamine deprivation, or pharmacological inhibition by 2DG/DON significantly suppressed viral replication in mammalian cell lines. In vivo, however, differential tissue biodistribution dictated that neither inhibitor reduced viral loads in serum or foot tissues of acute infected mice following footpad inoculation with 10⁴ PFU CHIKV. Strikingly, DON, but not 2DG, abolished histopathological manifestations of myositis and inflammatory infiltration despite comparable viral burdens. Mechanistically, DON-mediated tissue protection was related to dual immunomodulation. DON significantly depleted splenic innate immune cells, including monocytes and macrophages, which play roles in driving tissue inflammatory infiltration cascades. Meanwhile, DON inhibited CD4 + and CD8+ T cell effector programmes, resulting in suppressed activation marker (CD44) expression and effector cell differentiation (decreased effector: naive ratio and TEM: TCM balance). The proliferative capacity (Ki-67 + cells), polyfunctional cytokine responses (IFN-γ+, TNF-α and IL-17 + cells) and cytotoxicity potential (CD107a + cells) of CD4 + and CD8+ T cells were significantly impaired by DON injection. Crucially, glutaminolysis inhibition uncoupled immunopathology from viral containment, attenuating tissue damaging immunity while preserving baseline antiviral competence. Collectively, these findings establish host glutamine metabolism as a pharmacologically tractable target for alphavirus-induced arthritis, demonstrating that selective immunometabolic modulation resolves the severe acute inflammatory pathology.