We next measured FXN gene expression in pHR'SIN-cPPT-SFFV-FXN-WPRE-infected cells using quantitative real-time PCR (qRT-PCR) at 2, 8 and 12 weeks post infection compared with uninfected cells and control normal human and mouse fibroblasts to determine levels and longevity of gene expression. The gene discussed is FXN; the disease is infection.