The effect of temperature on the in vitro transcriptase reaction of bluetongue virus, epizootic haemorrhagic disease virus and African horsesickness virus

Abstract

Virions of bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV) and African horsesickness virus (AHSV) can be converted to core particles by treatment with chymotrypsin and magnesium. The conversion is characterized by the removal of the 2 outer capsid polypeptides of the virion. The loss of these 2 proteins results in an increase in density from 1,36g/ml to 1,40g/ml on CsC1 gradients. The BTV, EHDV and AHSV core particles have an associated double-stranded RNA dependent RNA transcriptase that appears to transcribe mRNA optimally at 28⁰C. It was found, at least in the case of BTV, that this low temperature preference is not an intrinsic characteristic of the transcriptase, but is due to a temperature-dependent inhibition of transcription at high core concentrations.