Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)
PRRSV is a member of the family Arteriviridae, genus Arterivirus. The name of this recently established family is derived from the disease caused by its type species, equine arteritis virus. Apart from horses, arteriviruses infect swine, causing "mystery swine disease", which was first detected in North America in 1987 and in Europe in 1990 and has since then become a major threat to swine industries in many countries. Porcine reproductive and respiratory syndrome (PRRS, also known as "Blue Ear" disease) is characterised by reproductive failure of sows and respiratory distress of piglets. PRRSV is distributed world-wide except Australia.
Arterivirus virions are 50-70 nm in diameter and consist of an isomeric (probably icosahedral) nucleocapsid, 35 nm in diameter, surrounded by a closely adherent envelope with honeycomb-like surface structures. The genome consists of a single molecule of linear positive-sense, ssRNA, 13 to 15 kb in size.
Arteriviruses replicate in the perinuclear cytoplasm of their host cells, usually macrophages. Genomic RNA is synthesized via full-length, negative-sense replicative intermediate. Virions bud through membranes of the endoplasmic reticulum into intracellular vesicles; from there they move to the surface of the cell in vesicles and are released by exocytosis. The primary target cell of the virus is the alveolar macrophage of the pig.
Two major antigenic types of the virus exist, the European and the American type, clearly reflecting another phylogenetic split that perhaps is indicative of recent transmission patterns.
The virus spreads quickly in native swine populations, with up to 95% of swine in a herd becoming seropositive within 2-3 months after an introduction.
PRRS occurs in most major pig-producing areas throughout the world. The reproductive failure is characterised by abortions, stillbirths, and the birth of weak piglets that often die soon after birth of respiratory disease and secondary infections. Older pigs may demonstrate mild signs of respiratory disease, sometimes complicated by secondary infections. Animals other than pigs do not seem to be affected by PRRS. PRRS is classified as an OIE List B disease.
More information about PRRSV can be obtained:
[ CSFV |
ASFV |
PRRSV |
ADV |
PPV |
SVDV |
FMDV |
VSV ]
