[Studies on establishment and maintenance of persistent infection with measles virus in NC-37 cell. III. Role of interferon in establishment and maintenance of persistent infection (author's transl)].

Human lymphoblastoid cell, NC-37, persistently infected with measles virus could always produce interferon in culture medium. Persistently infected cells were sensitive to interferon and acquired antiviral state, but normally yielded infectious progeny virus in culture fluid. Sensitivity of measles virus to interferon was studied because measles virus continued to replicate in these persistently infected cell. Attenuated and SSPE viruses which established persistent infection were relatively resistant to antiviral effect of interferon while wild strain had a sensitivity. Interferon produced endogenously in these persistently infected cells did not play an important role in maintenance of persistent infection caused by the suppression of virus replication. As it was found that persistently infected cell treated with interferon as high as 10(4) units/ml was significantly decreased virus yield in parallel with hemadsorption, it is suggested that endogenous measles virus which has been replicate in persistently infected cell might be also sensitive to high titer of interferon. NC-37 cell pretreated with interferon (10(3) units/ml) was infected with wild strain of measles virus. The treated cell led to decrease approximately 30% of virus yield and hemadsorption at the time when maximum yield was obtained in control cell, and that cell death reduced one week, but persistent infection could not be established.