Vesicular Stomatitis Virus Growth in Drosophila melanogaster Cells. II. Modifications of Viral Protein Phosphorylation

Abstract

SUMMARYThe phosphoproteins of vesicular stomatitis virus released from infected Drosophila melanogaster cells were examined. The membrane (M) protein was more phosphorylated than after multiplication in chicken embryo cells, even in Drosophila cell cytoplasm before its association with cellular membranes. Analysis of phosphopeptides generated after partial proteolysis and of phosphoamino acids obtained after complete acid hydrolysis showed that M phosphorylation was quantitatively and qualitatively changed, while NS protein phosphorylation was only slightly modified.

Restricted Expression of Viral Glycoprotein in Vesicular Stomatitis Virus-infected Drosophila melanogaster Cells

“…As shown in the present study, the translation rate of the external membrane glycoprotein, as well as its insertion in the virion membrane or its secretion as soluble antigens, were reduced. As previously reported, the phosphorylation of the inner membrane protein M is quantitatively and qualitatively changed in insect cells (Blondel et al, 1983). Modifications specifically affecting the viral envelope proteins are also a characteristic common to RNA viruses in persistently infected vertebrate cells, e.g.…”

“…The amounts increased during the first few hours 12-fold fewer VSV transcripts than a C E R cell. Since it has previously been shown that only VSV full-length m R N A s accumulate in Drosophila cells (Blondel et al, 1988), these results indicate that the transcription rate and turnover of N and G m R N A s are not markedly different. G protein synthesis is thus affected during a post-transcriptional step in which messenger maturation and also the translation process on membrane-bound polysomes could be involved.…”

“…Cells were infected under one-step growth conditions. Cellular nucleic acids were extracted at the indicated times and serial dilutions of each sample were dotted onto the membrane In Drosophila cells, N and G m R N A s followed the same accumulation pattern as all transcription products (Blondel et al, 1988). The amounts increased during the first few hours 12-fold fewer VSV transcripts than a C E R cell.…”

“…After autoradiography ( Fig. 1 a and Hybridization experiments and quantification were performed as previously described (Blondel et al, 1988). Cells were infected under one-step growth conditions.…”

“…The accumulation of G protein mRNA and of nucleocapsid N protein mRNA, used as a reference, was compared throughout the multiplication of VSV Indiana in D. melanogaster cells (line 770M3) and in CER hamster cells. Hybridization experiments on dot blots were performed as previously described (Blondel et al, 1988). At various times after infection, total cellular nucleic acids were extracted and dot blots were prepared with serial dilutions of each sample.…”