Chikungunya Virus Evades Antiviral CD8 + T Cell Responses To Establish Persistent Infection in Joint-Associated Tissues.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes explosive epidemics of a febrile illness characterized by debilitating arthralgia and arthritis that can endure for months to years following infection. In mouse models, CHIKV persists in joint tissues for weeks to months and is associated with chronic synovitis. Using a recombinant CHIKV strain encoding a CD8 ⁺ T cell receptor epitope from ovalbumin, as well as a viral peptide-specific major histocompatibility complex class I tetramer, we interrogated CD8 ⁺ T cell responses during CHIKV infection. Epitope-specific CD8 ⁺ T cells, which were reduced in Batf3 ^-/- and Wdfy4 ^-/- mice with known defects in antigen cross-presentation, accumulated in joint tissue and the spleen. Antigen-specific ex vivo restimulation assays and in vivo killing assays demonstrated that CD8 ⁺ T cells produce cytokine and have cytolytic activity. Despite the induction of a virus-specific CD8 ⁺ T cell response, the CHIKV burden in joint-associated tissues and the spleen were equivalent in wild-type (WT) and CD8α ^-/- mice during both the acute and the chronic phases of infection. In comparison, CD8 ⁺ T cells were essential for the control of acute and chronic lymphocytic choriomeningitis virus infection in the joint and spleen. Moreover, adoptive transfer of virus-specific effector CD8 ⁺ T cells or immunization with a vaccine that induces virus-specific effector CD8 ⁺ T cells prior to infection enhanced the clearance of CHIKV infection in the spleen but had a minimal impact on CHIKV infection in the joint. Collectively, these data suggest that CHIKV establishes and maintains a persistent infection in joint-associated tissue in part by evading CD8 ⁺ T cell immunity. IMPORTANCE CHIKV is a reemerging mosquito-transmitted virus that in the last decade has spread into Europe, Asia, the Pacific Region, and the Americas. Joint pain, swelling, and stiffness can endure for months to years after CHIKV infection, and epidemics have a severe economic impact. Elucidating the mechanisms by which CHIKV subverts antiviral immunity to establish and maintain a persistent infection may lead to the development of new therapeutic strategies against chronic CHIKV disease. In this study, we found that CHIKV establishes and maintains a persistent infection in joint-associated tissue in part by evading antiviral CD8 ⁺ T cell immunity. Thus, immunomodulatory therapies that improve CD8 ⁺ T cell immune surveillance and clearance of CHIKV infection could be a strategy for mitigating chronic CHIKV disease.
(Copyright © 2020 American Society for Microbiology.)