The polypeptides induced in Drosophila cells by Drosophila C virus (strain Ouarzazate)

Inhibition of the induction of heat shock proteins in Drosophila melanogaster cells infected with insect picornaviruses

“…Furthermore, all the virus-induced proteins were more apparent in the heat treated cells (6-8, fig.4) because of selective inhibition of host cell protein synthesis. Precursor proteins E, F and G were eliminated completely at high iodoacetamide concentration [4] but residual amounts of these 3 proteins were apparent after long heat-shock. …”

“…This protein is a novel virus precursor attributed to the heat-mediated inhibition of protein processing of precursors to virus structural proteins [9]. This protein corresponds to the high molecular mass precursor (A3) obtained by iodoacetamide treatment of infected cells [4] as seen in fig.4 (2-5). Induced proteins A3 and D originally found in substantial amounts only with iodoa~etamide treatment were found also in the heat-shocked cells (fig.4).…”

“…Cells were heat-shocked at 37°C for 15 min (l- 4) and 5 min (5-8) or maintained at 28°C (9)(10)(11)(12) prior to pulsing with 200 &i of "S for 15 min at 4.5 h post-infection.…”

“…Cells were grown to confluency in Schneider's medium containing 10% foetal calf serum and antibiotics while virus was grown in cells maintained on Schneider's medium containing 2% foetal calf serum and antibiotics [3]. Virus was titred as 50% tissue culture infectivity doses (KID,,) in Falcon Microtest plates [2,4].…”

“…The recently characterised picornaviruses of insects have been shown to act similarly, with Cricket paralysis virus (CrPV) being extremely efficient in inhibitingDrosophila cell protein synthesis [2,3], whereas the related Drosophila C virus (DCV) is relatively inefficient [4]. Effort has been concentrated on the elucidation of the shut-off mechanisms although this has not led to a satisfactory model being established.…”