Characterization of an arterivirus defective interfering RNA. Replication and homologous recombination.

Abstract

Recently, we have described the generation of DI-b, a natural equine arteritis virus (EAV) defective interfering (DI) RNA of 5.6 kb, and we have reported the construction of pEDI, a full-length cDNA copy of EAV DI-b RNA from which replication-competent RNA can be transcribed in vitro (Molenkamp et al., 2000a, Molenkamp et al., 2000b). EDI RNA consists of three noncontiguous parts of the EAV genome fused in frame with respect to the replicase gene (Fig. 1). As a result the EDI RNA contains a truncated replicase open reading frame (ORF), which we will refer to as EDI-ORF. The importance of such a translation unit in Coronavirus DI RNA propagation has been shown by a number of researchers (de Groot et al., 1992; van der Most et al.,1995; Liao and Lai, 1995).