Induction de la synthèse d'interféron par des RNA bicaténaires: I. Application à l'étude du cycle de multiplication du virus Mengo (I)

Abstract

Interferon inducing capacity of double-stranded RNA. I. Studies on Mengo virus replication Total RNA from Mengo infected L cells (RNA-IC) induces interferon in mice when inoculated in microgram amounts intraperitoneally and intravenously (Fig. 2). The inducer is resistant to ribonuclease (100 μg, 22°, 30 min in 0.3 M NaCl-0.03 M trisodium citrate and formaldehyde (1.5%), respectively. The kinetics of synthesis of the inducer during Mengo virus multiplication is shown in Fig. 3: after exponential growth, maximal amounts of inducer are observed at 6 h. The data presented in Fig. 4 illustrate a sucrose density gradient profile of RNA-IC; 2 mice were inoculated with each fraction and the interferon in the serum was titrated. A peak inducing activity was found at 16 S. Heavy labelled RNA-IC with [5- 3H]uridine was fractionated by density gradient (Fig. 5A, 5B). Acid-insoluble radioactivity of each fraction was measured before and after ribonuclease treatment (10 μg/fraction). The inducing interferon activity was also determined. Both peaks were superposable. When 3H-labelled RNA-IC was treated with ribonuclease before sedimentation, acid-insoluble radioactivity and interferon induction peaks were still coincident but displaced to the lighter side of the gradient. Sedimentation rates slower than viral single-stranded RNA and ribonuclease resistance are characteristics of double-stranded replicative form. Interferon inducing capacity appears to be an added property which might be of value in the search for other replicative forms.