Replication of herpesviruses in human cells transformed by cytomegalovirus.

The replication of human cytomegalovirus (CMV) and herpes simplex virus (HSV) was studied in three human embryo cell lines (CMV-Mj-HEL-I, CMV-Mj-HEL-2, and CMV-Mj-HEL-2,T-I) transformed in vitro by human CMV. Growth studies revealed that these cells were completely resistant to infection by CMV strains ADI69 and Mj and partially resistant to HSV types I and 2. Neither virus DNA nor virus proteins were synthesized in the transformed cells infected with CMV AD169. The HSV production in CMV-transformed human embryo lung (HEL) cells was delayed when compared to the virus production in normal HEL cells and spread of HSV c.p.e. was slower in the transformed cells. The treatment of normal HEL cells with a crude extract of CMV-transformed HEL cells also resulted in inhibition of the spread of c.p.e. of HSV types I and 2. The inhibitory effect was not due to interferon since vesicular stomatitis virus replication was not affected and several experiments showed that it was not due to mycoplasma. The presence of virus inhibitor molecules in CMV-transformed cells absent in normal HEL cells is postulated.