Combined TLR7/8 and TLR9 Ligands Potentiate the Activity of a Schistosoma japonicum DNA Vaccine
Mouse mammary tumor virus (MMTV) is a milk-borne betaretrovirus that has developed strategies to exploit and subvert the host immune system. We have shown in a natural model of MMTV infection that the virus causes early and progressive increases in superantigen (Sag)-specific CD4+ CD25+ Foxp3+ regulatory T cells (Treg) in Peyer's patches. Herein, we evaluated whether the depletion of Treg cells affects the CD8+ population during milk-borne MMTV infection. At day 6 of infection, the depletion of Treg cells increased the percentage and absolute number of CD8+ cells in lymph nodes as well as the mean intensity fluorescence of the CD44 activation marker. The absolute number of CD8+ cells was increased in cells bearing both Sag reactive and non-reactive TCR Vβ chains. We have previously shown that regulatory T cell depletion at day 6 of infection decrease viral load. Results reported herein suggest that at least after day 6 of MMTV infection Treg cells play an inhibiting role on CD8 antiviral response.