CD4 and Japanese encephalitis: These results suggest that CCR5+CD4+Foxp3+ Tregs purified from Ccr5+/+·Foxp3GFP mice could ameliorate JE progression in Ccr5−/− mice, in contrast with CCR5-CD4+Foxp3 Tregs purified from Ccr5−/−.Foxp3GFP mice.