[Studies on establishment and maintenance of persistent infection with measles virus in NC-37 cell. II. Effect of DNA-synthesis-suppressing factor (DSF) on the production of interferon in NC-37 cell infected with measles virus (author's transl)].

The attenuated strain of measles viruses, Schwarz, CAM-70, or subacute sclerosing panencephalitis (SSPE) virus of measles viruses, Halle, Mantooth was good interferon inducer, but the virulent strain, Edmonston, Toyoshima induced few amount of interferon or not. Furthermore, an inverse relationship seemed to exist between the ability to induce interferon and DNA synthesis suppressing factor (DSF). The attenuated strain or SSPE virus which had not a capacity to produce DSF could induce interferon and establish persistent infection in human lymphoid cell NC-37, while virulent strain did not induce interferon but DSF. Maximum yield of progeny virus was precede the detection of interferon in culture fluids. A persistently infected cells also produced continuously interferon and progeny virus. It is demonstrated that DSF suppressed interferon production by infection of measles virus and that DSF had not an activity like interferon.