In order to obtain an HER2-retargeted recombinant more efficient in terms of the infection of murine cancer cells, and, possibly, of human cells, the two gB mutations were inserted in R-LM249 (Figure 6A), thus generating R-291.The linear maps of R-291 gD and gB are shown in Figure 6B. The replication of R-291 in human cancer cell lines, positive or negative for HER2 expression, was compared to that of its parental R-LM249. The gene discussed is ERBB2; the disease is cancer.