Yellow head virus | |
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Yellow head virus virion | |
Yellow head virus genome | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Pisuviricota |
Class: | Pisoniviricetes |
Order: | Nidovirales |
Family: | Roniviridae |
Genus: | Okavirus |
Subgenus: | Tipravirus |
Species: | Yellow head virus |
Yellowhead disease (YHD) is a viral infection of shrimp and prawn, in particular of the giant tiger prawn (Penaeus monodon), one of the two major species of farmed shrimp. The disease is caused by the Yellow head virus genotype 1 (YHV1), a positive-strand RNA virus related to coronaviruses and arteriviruses.
The disease is highly lethal and contagious, killing shrimp quickly. Outbreaks of this disease have wiped out in a matter of days the entire populations of many shrimp farms that cultivated P. monodon, i.e. particularly Southeast Asian farms. In Thai, the disease is called hua leung. [1] A closely related virus is the Gill-associated virus (GAV). [2]
The cephalothorax of infected shrimp turns yellow after a period of unusually high feeding activity ending abruptly, and the then moribund shrimps congregate near the surface of their pond before dying. YHD leads to death of the animals within two to four days. [3]
YHD had been reported first from Thailand in 1990, the closely related GAV has been discovered in 1995 during a yellowhead-like disease in Australian shrimp farms.
Whiteleg shrimp, also known as Pacific white shrimp or King prawn, is a species of prawn of the eastern Pacific Ocean commonly caught or farmed for food.
The Indian prawn, is one of the major commercial prawn species of the world. It is found in the Indo-West Pacific from eastern and south-eastern Africa, through India, Malaysia and Indonesia to southern China and northern Australia. Adult shrimp grow to a length of about 22 cm (9 in) and live on the seabed to depths of about 90 m (300 ft). The early developmental stages take place in the sea before the larvae move into estuaries. They return to the sea as sub-adults.
Okavirus is a genus of enveloped positive-strand RNA viruses which infect crustaceans. Host organisms are mostly shrimp. It is the only genus in the family Roniviridae. Viruses associated with the genus include: gill-associated virus (GAV) which causes reddening, biofouling with exoparasites, emaciation, and massive mortality; and yellow head virus (YHV) which causes yellow head, arrest of feeding, and massive mortality. The name is derived from the 'Oka' or lymphoid organ in which the viruses are commonly detected and in which pathology occurs during acute infections. Lymphoid organs are anatomical structures common to penaeid shrimp. There are three species in this genus.
Hepeviridae is a family of viruses. Human, pig, wild boar, sheep, cow, camel, monkey, some rodents, bats and chickens serve as natural hosts. There are two genera in the family. Diseases associated with this family include: hepatitis; high mortality rate during pregnancy; and avian hepatitis E virus is the cause of hepatitis-splenomegaly (HS) syndrome among chickens.
Marine shrimp farming is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Although traditional shrimp farming has been carried out in Asia for centuries, large-scale commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe. The total global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9 billion U.S. dollars. About 75% of farmed shrimp is produced in Asia, in particular in China and Thailand. The other 25% is produced mainly in Latin America, where Brazil, Ecuador, and Mexico are the largest producers. The largest exporting nation is India.
A freshwater prawn farm is an aquaculture business designed to raise and produce freshwater prawns or shrimp for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farming. Unique problems are introduced by the developmental life cycle of the main species.
White spot syndrome (WSS) is a viral infection of penaeid shrimp. The disease is highly lethal and contagious, killing shrimp quickly. Outbreaks of this disease have wiped out the entire populations of many shrimp farms within a few days, in places throughout the world.
Taura syndrome (TS) is one of the more devastating diseases affecting the shrimp farming industry worldwide. It was first described in Ecuador during the summer of 1992. In March 1993, it returned as a major epidemic and was the object of extensive media coverage. Retrospective studies have suggested a case of Taura syndrome might have occurred on a shrimp farm in Colombia as early as 1990 and the virus was already present in Ecuador in mid-1991. Between 1992 and 1997, the disease spread to all major regions of the Americas where whiteleg shrimp is cultured. The economic impact of TS in the Americas during that period might have exceeded US$2 billion by some estimates.
Infectious hypodermal and hematopoietic necrosis (IHHN) is a viral disease of penaeid shrimp that causes mass mortality among the Western blue shrimp and severe deformations in the Pacific white shrimp. It occurs in Pacific farmed and wild shrimp, but not in wild shrimp on the Atlantic coast of the Americas. The shrimp-farming industry has developed several broodstocks of both P. stylirostris and P. vannamei that are resistant against IHHN infection.
Shrimp farming is an aquaculture business that exists in either a marine or freshwater environment, producing shrimp or prawns for human consumption.
Penaeus is a genus of prawns, including the giant tiger prawn, the most important species of farmed crustacean worldwide. The genus has been reorganised following a proposition of Pérez Farfante and Kensley based on morphological differences, in particular the genital characteristics of these animals, although this revision has not been universally accepted. Following the revision, many species formerly in the genus Penaeus have been reassigned to new genera in the family Penaeidae: Farfantepenaeus, Fenneropenaeus, Litopenaeus, and Marsupenaeus. The following table gives an overview:
Penaeus monodon, commonly known as the giant tiger prawn, Asian tiger shrimp, black tiger shrimp, and other names, is a marine crustacean that is widely reared for food.
African horse sickness (AHS) is a highly infectious and often fatal disease caused by African horse sickness virus. It commonly affects horses, mules, and donkeys. It is caused by a virus of the genus Orbivirus belonging to the family Reoviridae. This disease can be caused by any of the nine serotypes of this virus. AHS is not directly contagious, but is known to be spread by insect vectors.
Aujeszky's disease, usually called pseudorabies in the United States, is a viral disease in swine that has been endemic in most parts of the world. It is caused by Suid herpesvirus 1 (SuHV-1). Aujeszky's disease is considered to be the most economically important viral disease of swine in areas where classical swine fever has been eradicated. Other mammals, such as cattle, sheep, goats, cats, dogs, and raccoons, are also susceptible. The disease is usually fatal in these animal species.
Nudiviruses are a family of animal viruses that constitute the family Nudiviridae. Insects and marine crustaceans serve as natural hosts. There are 11 species in this family, assigned to 4 genera. Diseases associated with this family include: death in larvae, chronic disease in adults.
Penaeus esculentus is a species of prawn which is widely fished for consumption around Australia.
Marsupenaeus is a monotypic genus of prawn. It contains a single species, Marsupenaeus japonicus, known as the kuruma shrimp, kuruma prawn, or Japanese tiger prawn. It occurs naturally in bays and seas of the Indo-West Pacific, but has also reached the Mediterranean Sea as a Lessepsian migrant. It is one of the largest species of prawns, and is accordingly one of the most economically important species in the family.
Shrimp are crustaceans with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are referred to as "shrimp".
Eyestalk ablation is the removal of one (unilateral) or both (bilateral) eyestalks from a crustacean. It is routinely practiced on female shrimps in almost every marine shrimp maturation or reproduction facility in the world, both research and commercial. The aim of ablation under these circumstances is to stimulate the female shrimp to develop mature ovaries and spawn.
Penaeus semisulcatus, the green tiger prawn or grooved tiger prawn, is a commercially important species of prawn in the genus Penaeus.