# Identification of a TCR signature in peripheral blood derived CD4+ T cells, associated with chronic chikungunya disease, suggests a conducive, female-biased, background immune profile

## TL;DR

Researchers found a specific T cell receptor signature in CD4+ T cells linked to chronic chikungunya disease, suggesting a female-biased immune background may increase disease risk.

## Contribution

The study identifies a novel TCR signature in CD4+ T cells associated with chronic chikungunya disease and highlights a sex-biased immune predisposition.

## Key findings

- Eight TCR clusters were differentially enriched in chronic versus non-chronic chikungunya patients.
- TRAV9-2 and TRAV41.2 were increased in chronic patients, while TRAV41.3 and TRBV18 were decreased.
- Female controls had higher TRAV9-2 frequencies, suggesting a pre-existing immune bias linked to CCD susceptibility.

## Abstract

Chronic chikungunya disease (CCD) is characterized by persistent inflammatory joint pains following acute chikungunya virus (CHIKV) infection in about half of the patients . CD4+ T cells have been implicated in CCD pathogenesis, yet disease-associated T cell receptor (TCR) signatures remain undefined.

Peripheral blood CD4+ T cells were collected from 65 Cambodian participants six months after RTqPCR–confirmed CHIKV infection during the 2020 outbreak, including chronic (n=16), non-chronic (n=16), and control (n=33) individuals. TCR α, β, γ, and δ CDR3 regions were sequenced and clustered using ClusTCR. Differential enrichment was assessed by Fisher’s exact test. L1-regularized logistic regression incorporating age, gender, and TCR clone counts was used to identify non-redundant TCR signatures.

Eight TCR clusters were differentially enriched between chronic and non-chronic patients. Chronic disease was associated with increased TRAV9-2 and TRAV41.2 and decreased TRAV41.3 and TRBV18 clone counts. Female controls exhibited higher baseline TRAV9-2 frequencies, suggesting a pre-existing, female-biased immune background associated with CCD susceptibility.

A distinct CD4+ TCR signature detectable six months post-infection characterizes patients who develop CCD. The association of TRAV9-2 with chronic disease and its enrichment in females suggests an underlying immune predisposition rather than persistent virus-driven expansion. These findings support a role for CD4+ T cells in CCD pathophysiology and identify candidate TCR-based biomarkers for disease risk stratification.