Interaction of M protein and RNP of fowl plague virus in vitro.

The ability of the fowl plague virus (FPV) M protein to form a complex with FPV RNP and to inhibit the RNP transcriptase activity in vitro depended on NaCl concentration and did not depend on the concentration of nonionic detergents. The results obtained indicate that the M protein-RNP links formed were of an electrostatic rather than a hydrophobic nature. As demonstrated using individual RNP components, vRNA and RNA-free protein structures, M protein formed complexes only with vRNA, and the complex formation was salt-dependent. Analysis of products formed in the in vitro system containing RNP of FPV in the presence of the M protein showed impairment in the transcription of all RNA segments. The degree of inhibition correlated with the size of a segment, transcription of high molecular weight RNA segments being inhibited significantly more than that of low molecular weight RNA segments.