Measles virus polypeptide synthesis in infected cells

Abstract

The synthesis of measles virus polypeptides has been studied using an inhibitor of virus-induced cell fusion, carbobenzoxy- d-phenylalanyl- l-phenylalanyl-nitro- l-arginine (SV4814). Cells infected at a multiplicity of 10 fuse extensively by 17 hr and die shortly thereafter, making it difficult to detect viral polypeptides. Cells protected from fusion by SV4814 survive and continue to produce virus, and the synthesis of viral polypeptides can be followed for 4 days. The previously described measles virion polypeptides G, 2, NP, 5, and M have been identified in infected cells, and, in addition, a polypeptide (L) with a molecular weight of ∼200,000 has been found in infected cells and in small amounts in virions. (New designations suggested for polypeptides G, 2, and 5 are H, P, and F 1, respectively.) A glycosylated polypeptide ( F 0, MW ∼62,000) has also been found in infected cells, but not in virions. This polypeptide is thought to be the precursor of two polypeptides which appear under pulse-chase conditions: F 1 (MW ∼40,000), which is not glycosylated, and F 2, a small glycosylated polypeptide detected with [ 3H]glucosamine labeling. In addition to facilitating studies of measles virus polypeptide synthesis, the use of SV4814 has shown that cell fusion is the major factor in early cell death caused by measles virus, but that cell death ultimately ensues in the absence of cell fusion, indicating another mechanism of measles virus-induced cell damage.