CD4 and infection: The proportion of CD4+FoxP3+Tregs correlates positively with the lymphocyte number and viral load but negatively or inversely correlated with IFNγ levels in BLV infected cattle [28].The frequencies and representation of CD4+CD25highFoxP3+ T cells and TGF-β+ cells were shown to be increased in response to infection suggesting a role for TGF-β in the dysfunction of CD4+ T cells and NK cells [29].