ABSTRACT
A nonsegmented negative strand RNA virus, by definition, is distinguished by having a unipartite RNA genome that is complementary to and, hence, the template for the (positive polarity) mRNAs it encodes. Packed within the membrane envelope of each of the nonsegmented negative strand viruses is the viral nucleocapsid. This consists of a single strand genome RNA molecule, 11 to 15 kilobases in length, compactly wrapped in a nucleocapsid protein (circa 50 kdaltons) designated either N or NP. The central feature of the replicative cycle of a nonsegmented negative strand virus, then, is the synthesis of RNA catalyzed by a viral RNA polymerase. This is the major point of control during infection. For Vesicular stomatitis virus (VSV) it has been shown that viral macromolecular synthesis is governed mainly by the rates of transcription of the various viral genes. The transcribing nucleocapsid of VSV is composed of the viral genome and the viral proteins N, L, and NS.
