Coronin 1 is a member of the evolutionary conserved WD repeat protein family and is highly expressed in hematopoietic cells. Coronin 1 is essential for Ca(2+) mobilization upon T cell receptor (TCR) stimulation providing a pro-survival signal for naïve peripheral T cells. Both in mouse and in human, coronin 1 deficiency is associated with severe T cell lymphopenia. In this work, we have analyzed antiviral T cell-mediated immunity in the presence and absence of coronin 1 in vivo after infection with lymphocytic choriomenigitis virus (LCMV) and vesicular stomatitis virus (VSV) in mice. Despite low peripheral T cell numbers we found that LCMV-specific CD8(+) T cell responses were normal in the absence of coronin 1 and kinetics of LCMV-clearance were similar compared to wild type mice. In contrast, CD4(+) T cell responses were profoundly decreased after LCMV- and VSV-infection. We propose that coronin 1 plays a differential role in CD8(+) versus CD4(+) T cell responses and activation.