CD4 and infection: However, using the same transgenic mice, another study linked the GM-CSF-induced protection to enhanced CD103+ DC-mediated antiviral T cell responses, although numbers of DCs and virus-specific CD4+ and CD8+ T cells in SPC-GM mice were comparable to non-transgenic WT mice and the viral load was significantly reduced as early as day 3 post-infection prior CD8+ T cell expansion and effector function [27].