CD4 and HIV infectious disease: However, there is also a significant CD4 T-cell response to HIV infection as well during PHI (Rosenberg et al., 2000; Oxenius et al., 2001; Gloster et al., 2004; Kaufmann et al., 2004; Zaunders et al., 2005; Maenetje et al., 2010; Riou et al., 2012).