Equine arteritis virus contains a unique set of four structural proteins.

Equine arteritis virus (EAV) belongs to a group of small enveloped positive-stranded RNA viruses, provisionally designated arteriviruses, which further includes lactate dehydrogenase-elevating virus (LDV), simian hemorrhagic fever virus (SHFV), and swine infertility and respiratory syndrome virus (SIRSV) or Lelystad virus (LV). These viruses resemble togaviruses in their physicochemical properties, the polarity and size (13–15 kb) of their genomes, and the size (50–70 nm) and morphology (isometric) of the virionsl,2 but virus assembly occurs by intracellular budding1,3. In contrast, the genome organization and gene expression strategy are similar to those of corona-and toroviruses2,4,5,6,7,8.