5-Bromodeoxyuridine enhancement of Inoue-Melnick virus synthesis in human colon carcinoma cell lines

Inoue-Melnick virus (IMV) synthesis in naturally infected human colon carcinoma cell lines can be enhanced by 5-bromodeoxyuridine (BUDR). The optimal conditions for BUDR enhancement differed between two cell lines, SW-480 and DLD-1. SW-480 cells produced 100 times more infectious IMV than DLD-1 cells by BUDR treatment. A clonal difference in IMV synthesis in SW-480 cells was also observed. The highest titer of virus was found in the culture fluid of clone H (SW-480/H) cells treated with BUDR, and a herpes-like virus was detected by negative-staining electron microscopy of concentrates of the culture fluid. One nonproducer clone (SW-480/B) was also activated to produce virus when treated with BUDR.