The importance of CD4+ T cells in HBV flares is highlighted by IRIS in patients coinfected with HBV and HIV, as both HIV and HBV infections reduce CD4+ cell counts [103,104,105]; moreover, the rapid onset of hepatitis flares with an increased CD4+ T cell count after commencing HAART suggests the possibility of IRIS [106]. The gene discussed is CD4; the disease is Hepatitis.