Primary Clearance of Murine Gammaherpesvirus 68 by PKCθ−/−CD8 T Cells Is Compromised in the Absence of Help from CD4 T Cells

CD4 T cells are dispensable for acute control of murine gammaherpesvirus 68 (MHV-68) but are necessary for effective long-term control of the virus by CD8 T cells. In contrast, protein kinase C θ (PKCθ) is not essential for either acute or long-term viral control. However, we found that while either CD4 or CD8 T cells could mediate the clearance of MHV-68 from the lungs of PKCθ+/+ mice, PKCθ−/− mice depleted of either subset failed to clear the virus. These data suggest that there are two alternative pathways for MHV-68 clearance, one dependent on CD4 T cells and the other on PKCθ. Protection mediated by the latter appears to be short-lived. These observations may help to explain the differential requirement for PKCθ in various models of CD8 T-cell activation and differences in the costimulatory requirements for acute and long-term viral control.