Conditions necessary for inhibition of protein synthesis and production of cytopathic effect in Aedes albopictus cells infected with vesicular stomatitis virus.

Abstract

The relationship between the development of cytopathic effect (CPE) and the inhibition of host macromolecular synthesis was examined in a CPE-susceptible cloned line of Aedes albopictus cells after infection with vesicular stomatitis virus. To induce rapid and maximal CPE, two conditions were required: (i) presence of serum in the medium and (ii) incubation at 34 degrees C rather than at 28 degrees C. In the absence of serum, incubation of infected cultures at 34 degrees C resulted in a significant increase in viral protein and RNA synthesis compared with that observed at 28 degrees C. However, when serum was present in the medium, by 6 h after infection protein synthesis (both host and viral) was markedly inhibited when infected cells were maintained at 34 degrees C. RNA synthesis (host and viral) was also inhibited in vesicular stomatitis virus-infected cells maintained at 34 degrees C with serum, but somewhat more slowly than protein synthesis. Examination of polysome patterns indicated that when infected cultures were maintained under conditions which predispose to CPE, more than half of the ribosomes existed as monosomes, suggesting that protein synthesis was being inhibited at the level of initiation. In addition, the phosphorylation of one (or two) polysome-associated proteins was reduced when protein synthesis was inhibited. Our findings indicate a strong correlation between virus-induced CPE in the LT-C7 clone of A. albopictus cells and the inhibition of protein synthesis. Although the mechanism of the serum effect is not understood, incubation at 34 degrees C probably predisposes to CPE and inhibition of protein synthesis by increasing the amount of viral gene products made.