Finally, it is tempting to speculate that CIITA, which is expressed upon CD4+ T cell activation and increases viral protease levels, may also contribute to Casp8p41-mediated apoptosis, which may link CIITA to the decimation of T cells in the GALT during primary viremia [67] . Thymic epithelial cells [68] , cervical epithelial cells [69] , human colonic epithelial cells [70] and oral keratinocytes (normal human oral epithelial cells) [71] have all demonstrated in vitro the capability of being productively infected with HIV. Infection of epithelial cells provides potential in vivo significance to this study, especially considering that thymic epithelial cells constitutively express MHC class II (and thus CIITA) [28] . In addition, most other cells can be stimulated to express CIITA in the presence of IFN-c (i.e. a pro-inflammatory environment), which is induced during HIV infection of the GALT [72] . Overall, this study demonstrates that the function of CIITA may be more broad than previously thought. Given this previously undescribed role in enhancement of virion maturation, the precise consequences of CIITA expression during the HIV replicative cycle may provide rationale for the development of novel antiviral therapeutics.