RABIES VIRUS-M PROTEIN EXPRESSED IN ESCHERICHIA-COLI AND ITS REGULATORY ROLE IN VIRION-ASSOCIATED TRANSCRIPTASE ACTIVITY

Rabies virus M protein was expressed in Escherichia coli in the form o f a fusion protein with maltose binding protein (MBP) and purified by amylose affinity column chromatography after extraction. In order to i nvestigate the possible regulatory role of M protein in viral transcri ption, an assay system for rabies virion-associated transcriptase acti vity was established by using the ribonucleoprotein (RNP) cores prepar ed from purified virions. Analysis of the products of the transcriptio n assay system showed that the products are sensitive to RNase and are positive-strand RNA. Addition of the fusion protein to the system aft er cleavage with a proteinase Factor Xa (FXa), which cleaves the fusio n protein into the M protein and MBP, resulted in an efficient and dos e-dependent inhibition of the transcription. Furthermore, addition to the system of anti-M protein monoclonal antibody significantly restore d the transcription. Control experiments with the same transcription a ssaying system using rabies virus nucleoprotein expressed as a fusion protein with MBP and cleaved with FXa did not result in an inhibition of the transcription. These results suggest that the M protein of rabi es virus has the property to down-regulate virion-associated transcrip tion.