Flanders virus replication and protein synthesis

The prototype strain of Flanders virus (61-7484) has been adapted to grow in Vero cell cultures and a plaque assay has been developed. Electron micrographs of infected cells revealed rod-shaped virions budding in clusters from the plasma membrane, consistent with the tentative classification of Flanders virus as a member of the Rhabdoviridae. Viral proteins were identified by SDS-PAGE and immunological techniques using Flanders virus-specific antibodies. Eight virus-associated proteins were detected. The relative molecular weights obtained by SDS-PAGE were 180,000, 81,000, 54,000, 43,000, 33,000, 27,000, 23,000, and 19,000. Evidence is presented that two of these proteins (43,000 and 23,000 mol wt) are in vivo cleavage products. The 81,000 mol wt protein was glycosylated and phosphorylated and did not label well with [35S]methionine or 14C-amino acids. The 54,000 and 33,000 mol wt proteins were phosphorylated. When 35S-radiolabeled virus was purified by pelleting at 90,000 g followed by isopycnic sucrose gradient centrifugation, all eight virus proteins were present in the peak fractions which contained the radiolabel and infectivity.