Induction of apoptosis by equine arteritis virus infection

Equine arteritis virus (EAV) is the etiological agent of equine viral arter itis, a contagious viral disease of equids. EAV is the prototype virus of t he arteriviruses, a group of small enveloped viruses with positive single-s tranded RNA genomes. Because apoptosis or programmed cell death is believed to play an important role in the biogenesis of several cytopathogenic viru ses, we examined whether EAV was able to induce cell apoptosis in vitro. To do this, Vero cells were infected with EAV at a multiplicity of infection of 0.1 tissue culture infectious dose (TCID50) per cell, and analyzed at va rious time intervals for the appearance of apoptotic signs. Fragmentation o f chromosomal DNA into nucleosomal oligomers and caspase activation were ob served in the infected cells at the time (e.g. 24 h postinfection) where a noticeable cytopathic effect was observed. The kinetics of the DNA fragment ation correlated with that of the production of progeny virus, so that vira l multiplication was not interrupted by the apoptotic cell damage. All thes e data provide evidence that EAV is able to induce apoptotic cell death in vitro.