A highly creative mouse model that was recently described used transgenic mice carrying an inducible loxP-STOP-loxP luciferase reporter whose expression can be triggered after infection with pseudotyped HIV-1 that expresses Cre recombinase; hepatocytes from these mice are rendered susceptible to HIV entry by infection with intravenously injected recombinant human adenovirus serotype 5 encoding the human CD4 and CCR5 genes [43]. Here, CD4 is linked to infection.