DNGR-1 is dispensable for CD8+ T-cell priming during respiratory syncytial virus infection.

During respiratory syncytial virus (RSV) infection CD8(+) T cells both assist in viral clearance and contribute to immunopathology. CD8(+) T cells recognize viral peptides presented by dendritic cells (DCs), which can directly present viral antigens when infected or, alternatively, "cross-present" antigens after endocytosis of dead or dying infected cells. Mouse CD8α(+) and CD103(+) DCs excel at cross-presentation, in part because they express the receptor DNGR-1 that detects dead cells by binding to exposed F-actin and routes internalized cell debris into the cross-presentation pathway. As RSV causes death in infected epithelial cells, we tested whether cross-presentation via DNGR-1 is necessary for CD8(+) T-cell responses to the virus. DNGR-1-deficient or wild-type mice were intranasally inoculated with RSV and the magnitude of RSV-specific CD8(+) T-cell induction was measured. We found that during live RSV infection, cross-presentation via DNGR-1 did not have a major role in the generation of RSV-specific CD8(+) T-cell responses. However, after intranasal immunization with dead cells infected with RSV, a dependence on DNGR-1 for RSV-specific CD8(+) T-cell responses was observed, confirming the ascribed role of the receptor. Thus, direct presentation by DCs may be the major pathway initiating CD8(+) T-cell responses to RSV, while DNGR-1-dependent cross-presentation has no detectable role.