Electron Microscopic Analysis of the Effects of Psoralen and Interferon on Replicative Intermediates Formed During Encephalomyocarditis Virus Infection of Mouse L Cells.

摘要

Demonstration of the existence of base-paired RNA in replication intermediates of murine encephalomyocarditis virus is important in understanding the mechanism of viral replication, interferon induction, and the role of double-stranded RNA-requiring enzymes in the mode of interferon action. The psoralen derivative 4'-aminamethyl-4,5',8-tri-methylpsoralen was used to specifically modify possible base-paired regions of the replicative intermediate formed during encephalomyocarditis virus infection. Psoralen modified replicative intermediates were shown to be formed in-vitro and in intact cells. Psoralen-modified replicative intermediates were isolated and examined in the electron microscope. Electron microscopic analysis suggested that encephalomyocarditis replicative intermediates contain significant stretches of base-pairs in intact cells. Further, replicative intermediates from interferon-treated cells were significantly shorter than those from control cells. This result suggests that the interferon-treatment led to viral RNA degradation, possibly through production and action of 2', 5'-oligoadenylate. This study provides direct evidence that replicative intermediates of encephalomyocarditis virus contain base-pairs in intact cells, and are degraded as a result of interferon treatment.