FOXP3 and viral encephalitis: Because an increased number of CD4+CD25+Foxp3+ Treg cells is correlated with milder forms of encephalitis caused by flavivirus infection [58], this finding suggests that IFN-γ produced from CD4+ Th1 cells can affect the progression of JE without changing the number of CD4+CD25+Foxp3+ Treg cells.