In vitro inhibition of negative strand virus transcriptase activity by proteins soluble in acidic chloroform-methanol

The effect of proteins soluble in acidic chloroform-methanol (ACMS proteins) on the transcriptase activity of virus ribonucleoproteins (RNPs) in vitro has been studied. Experiments with ACMS membrane (M) proteins from type A and B orthomyxoviruses, as well as from vesicular stomatitis virus, showed that inhibition of the viral RNP transcriptase activity occurred when they interacted with M proteins isolated from viruses of a different serotype, or even of a different family. The presence of ACMS proteins capable of inhibiting the transcriptase activity of orthomyxovirus RNP in vitro was also detected in human blood plasma and among proteins produced by human leukocytes. Determination of the minimum concentration of M protein inhibiting the RNP transcriptase activity, and analysis of the fowl plague virus M protein-RNP complex formed in the in vitro system, showed that the M protein was capable of inhibiting RNP transcriptase activity at a M:RNP ratio of 0.1 to 0.2:1.