Identification of dengue type 2 virus-specific high molecular weight proteins in virusinfected BHK cells

Evidence is presented for the production in dengue type 2 virus (DEN-2)-infected BHK cells of large virus-specific proteins with molecular weights up to 250000. These proteins were.most prominent in lysates of cells which had been labelled with [35S]methionine for 7 to 15 min. During pulse chase experiments, these high mol. wt. proteins appeared to be converted into smaller, more stable, proteins with mol. wt. between 10000 and 98000. Finally, inhibition of proteolysis prevented the chasing of label from the high mol. wt. proteins to the smaller viral proteins which normally accumulate in DEN-2-infected cells. These findings are consistent with the idea that processing of large polyprotein precursors plays an important role in the production of flavivirus proteins. Flaviviruses (family Togaviridae) comprise a genus of more than 60 immunologically related viruses, most of which are transmitted by arthropods. The spherical virion is composed of an envelope, a single-stranded RNA genome of positive (mRNA)polarity (mol. wt. 3.9 x 106) and three structural proteins: aglycoprotein (E; mol. wt. 50 000 to 65 000), a capsid protein (C; mol