EQUINE ARTERITIS VIRUS SUBGENOMIC RNA-TRANSCRIPTION - UV INACTIVATIONAND TRANSLATION INHIBITION STUDIES

The expression of the genetic information of equine arteritis virus (E AV), an arterivirus, involves the synthesis of six subgenomic (sg) mRN As. These are 5' and 3' coterminal since they are composed of a leader and a body sequence, which are identical to the 5' and 3' ends of the genome, respectively. Previously, it has been suggested that cis-spli cing of a genome-length precursor RNA is involved in their synthesis. This was reevaluated in a comparative analysis of the sg RNA synthesis of EAV, the coronavirus mouse hepatitis virus (MHV), and the alphavir us Sindbis virus. UV transcription mapping showed that the majority of the EAV sg RNAs made at rater stages of infection is not derived from a genome-length precursor. However, complete independence of sg RNA s ynthesis from that of genomic RNA was never observed during the course of infection. The possibility that this resulted from UV irradiation- induced effects on the synthesis of the viral replicase was investigat ed by inhibiting translation using cycloheximide. For EAV, ongoing pro tein synthesis was found to be more important for the synthesis of sg RNA than for that of genomic RNA. In general, MHV transcription was ex tremely sensitive to translation inhibition, whereas EAV genomic RNA s ynthesis became independent of de novo protein synthesis late in infec tion. (C) 1995 Academic Press. Inc.