Analysis of AKR6 and 1E virus interference in CHO cells expressing the AAUU and AAAU chimeric receptors. CHO cells transduced by retroviral vectors expressing the chimeric receptors AAUU or AAAU were infected with AKR6 or 1E viruses by maintenance of the cells in virus-containing medium or in standard medium (mock infected) for six weeks. After infection the cells were seeded into 6-cm-diameter dishes, were exposed to vectors bearing the indicated Env, and vector titers were determined. Data from two independent infection/vector-titer-measurement experiments, one represented by grey boxes and the other by black boxes, are shown. Titer measurements in each experiment were performed in triplicate.