Vesicular stomatitis virus growth in Drosophila melanogaster cells: G protein deficiency

Abstract

In cultured Drosophila melanogaster cells, vesicular stomatitis virus (VSV) established a persistent, noncytopathic infection. No inhibition of host protein synthesis occurred even though all cells were initially infected. No defective interfering particles were detected, which would explain the establishment of the carrier state. In studies of the time course of viral protein synthesis in Drosophila cells, N, NS, and M viral polypeptides were readily detected within 1 h of infection. The yield of G protein and one of its precursors; G1, was very low at any time of the virus cycle; the released viruses always contained four to five times less G than those produced by chicken embryo cells, whatever the VSV strain or serotype used for infection and whatever the Drosophila cell line used as host. Actinomycin D added to the cells before infection enhanced VSV growth up to eight times. G and G1 synthesis increased much more than that of the other viral proteins when the cells were pretreated with the drug; nevertheless, the released viruses exhibited the same deficiency in G protein as the VSV released from untreated cells. Host cell control on both G-protein maturation process and synthesis at traduction level is discussed in relation to G biological properties.

Vesicular stomatitis virus in Drosophila melanogaster cells: lack of leader RNA transport into the nuclei and frequent abortion of the replication step

“…If a viral product were implicated, it could be modified by the host cells in a manner which changed its interactive properties towards leader RNA. In Drosophila cells, it has been shown that posttranslational maturation of some VSV proteins was affected, the M protein was hyperphosphorylated (3), and the G protein had an altered glycosylation pattern and was synthesized in low amounts (10,17,26,32). The N protein may also undergo posttranslation maturation, since in vertebrate cells three, four, and even five differently charged species have been resolved although it is encoded by only one gene (22); up to now, however, modifications of this protein in Drosophifa cells have not been described.…”

“…Cells and virus. D. melanogaster cells (line 770M3) were infected with a VSV Indiana stock (BT78, lot 1555) under the conditions previously described which permit a single-step infection (3,32). As a control, vertebrate cells (a hamster cell line called CER and described by Smith et al [27]) were infected in the same way.…”

Immunological cross-reactions and interactions between the Drosophila melanogaster ref(2)P protein and sigma rhabdovirus proteins

“…All preparation and labeling steps were carried out at 4°C. Embryos aged 0 to 16 h were washed in Shield culture medium (36) and gently sedimented to estimate the volume. They were homogenized in a glass grinder and resuspended at 0.5 ml of embryo pellet per 2 ml of Shield medium supplemented with 5% fetal calf serum and the CLAPA antiprotease mix.…”

“…In particular, the proteins of vesicular stomatitis virus (VSV) were synthesized in very large amounts after infection in cultured Drosophila cells (36). However none of the VSV proteins coprecipitated with the ref(2)P protein in the presence of T-REF antibodies under the conditions when sigma virus proteins coprecipitated (data not shown).…”

Translation of black beetle virus RNA and heterologous viral RNAs in cell-free lysates derived from Drosophila melanogaster

“…No products were detected that correspond in molecular weight to the viral glycoprotein (G) or its unglycosylated precursor. Vesicular stomatitis virus has recently been shown to grow in Drosophila cells, although, interestingly, a defect in the synthesis or maturation of the viral G protein was observed (23).…”