ARTERIVIRIDAE

A General Introduction has been added to each disease chapter in an attempt to give a brief updated overview of the taxonomic, biological and other characteristics of the virus family or group of bacteria /protozoa that cause disease in livestock and, where relevant, involve wildlife. As the text of the three-volume book Infectious Diseases of Livestock is currently under revision the Editors are aware that there are inconsistencies between the updated introductions to chapters and the content of the chapters themselves. Once the chapters have been updated – a process that is currently underway – these inconsistencies will be removed.

Arteriviruses were previously classified as a genus within the family Flaviviridae. However, it was subsequently found that arterivirus genome organization and replication are similar to coronaviruses but the genome and virions are only about half the size of those of coronaviruses. Although coronaviruses and arteriviruses both utilize a distinctive replication strategy that involves a nested set of subgenomic mRNAs, the nucleocapsid of Arteriviridae has an isometric rather than the helical configuration of coronaviruses; thus justifying the creation of a new family.

The family Arteriviridae, within the Order Nirovirales, comprises viruses that infect mammals, non-human primates particularly, and is divided into five genera, only two of which contain viruses that cause recognised diseases of domestic animals – Equartevirus (equine viral arteritis virus) and Porartevirus (porcine reproductive and respiratory syndrome virus).

Arteriviruses have a restricted host range and have the capacity to cause prolonged, asymptomatic infection in their natural hosts. They replicate primarily in macrophages and some have the ability to subvert host defences including apoptosis of infected macrophages and interferon signalling pathways. Replication occurs in the cytoplasm of infected cells although some viral proteins are translocated into cell nuclei. Newly formed virions mature in the Golgi complex before passing via the exocytic pathway to the cell exterior.

Virions are 45-60 nm in diameter and consist of an isometric nucleocapsid surrounded by a lipid envelope with indistinct glycoprotein projections. The genome consists of a linear molecule of single-stranded, positive sense RNA, about 13-15 kb in size that contains 9-12 open reading frames.

References

1. International Committee for Taxonomy of Viruses https://talk.ictvonline.org/taxonomy/ (accession date: 26/05/2017)
2. MACLACHLAN N.J. & DUBOVI, E.J. (eds.), 2016. Veterinary Virology, 5^th edition, Academic Press.