Unconventional repertoire profile is imprinted during acute chikungunya infection for natural killer cells polarization toward cytotoxicity

Chikungunya virus (chikv) is a worldwide emerging pathogen. in humans it causes a syndrome characterized by high fever,polyarthritis,and in some cases lethal encephalitis. growing evidence indicates that the innate immune response plays a role in controlling chikv infection. we show here that chikv induces major but transient modifications in nk-cell phenotype and function soon after the onset of acute infection. we report a transient clonal expansion of nk cells that coexpress cd94/nkg2c and inhibitory receptors for hla-c1 alleles and are correlated with the viral load. functional tests reveal cytolytic capacity driven by nk cells in the absence of exogenous signals and severely impaired ifn-γ production. collectively these data provide insight into the role of this unique subset of nk cells in controlling chikv infection by subset-specific expansion in response to acute infection,followed by a contraction phase after viral clearance. © 2011 petitdemange et al.