Jaagsiekte
Encyclopedia
Jaagsiekte is a chronic and contagious disease of the lungs in sheep and goats first described in 1865. Its name derives from Afrikaans
and means "Chasing Sickness" such that animals afflicted with the disease are in respiratory distress as if they are out of breath from being chased. It is also referred to as Ovine Pulmonary
Adenocarcinoma
(OPA). During end-stage disease, animals exude a foamy white fluid from the nose which is thought to be the mode of transmission between animals. Dissected lungs from afflicted sheep are interspersed with multifocal tumors. Some of these are small discrete nodules
and others will involve the entire half of a lung
lobule. The disease is caused by a retrovirus
called the Jaagsiekte Sheep Retrovirus
(JSRV
) that acutely transforms the lung epithelia
into cancerous cells. Specifically, Type-2 pneumocytes and Clara Cells
of the lung are the likely target for JSRV transformation. The tumors formed there exhibit the overactive secretory functions which are a hallmark of OPA.
OPA is an infectious disease of sheep and recently has been used as an animal model for human lung cancer. It is common in the UK and in South Africa
. The disease has a long incubation period and is not seen until sheep reach at least 2 years of age. Clinical symptoms include weight loss, loss of appetite, and respiratory difficulty which is associated with obvious movement of the abdomen and high pitched noises. Fluid accumulates in the respiratory tract and the disease ultimately causes death. The retroviral antigen
levels of JSRV are very high in OPA tumors and can be detected in the lung secretions of infected sheep. A common field assessment for Jaagsiekte is the "wheelbarrow
test" where one lifts the hind legs of the animal above the head to observe lung exudate
flow out the nose and mouth. This fluid contains infectious JSRV. It is thought that infected animals secrete the virus before showing clinical symptoms and the virus is therefore easily spread within flocks. The disease is histologically similar to human
bronchioalveolar carcinoma which accounts for approximately 25% of all diagnosed human lung cancers.
Dolly the sheep
, the first mammal successfully cloned from an adult somatic cell, was euthanized after it was confirmed that she had Jaagsiekte.
Afrikaans
Afrikaans is a West Germanic language, spoken natively in South Africa and Namibia. It is a daughter language of Dutch, originating in its 17th century dialects, collectively referred to as Cape Dutch .Afrikaans is a daughter language of Dutch; see , , , , , .Afrikaans was historically called Cape...
and means "Chasing Sickness" such that animals afflicted with the disease are in respiratory distress as if they are out of breath from being chased. It is also referred to as Ovine Pulmonary
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
Adenocarcinoma
Adenocarcinoma
Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...
(OPA). During end-stage disease, animals exude a foamy white fluid from the nose which is thought to be the mode of transmission between animals. Dissected lungs from afflicted sheep are interspersed with multifocal tumors. Some of these are small discrete nodules
Nodule (medicine)
For use of the term nodule in dermatology, see Nodule In medicine, a nodule refers to a relatively hard, roughly spherical abnormal structure....
and others will involve the entire half of a lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
lobule. The disease is caused by a retrovirus
Retrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...
called the Jaagsiekte Sheep Retrovirus
Jaagsiekte Sheep Retrovirus
Jaagsiekte sheep retrovirus is a betaretrovirus which is the causative agent of a contagious lung cancer in sheep called Jaagsiekte, or Ovine Pulmonary Adenocarcinoma .-Natural history:...
(JSRV
Jaagsiekte Sheep Retrovirus
Jaagsiekte sheep retrovirus is a betaretrovirus which is the causative agent of a contagious lung cancer in sheep called Jaagsiekte, or Ovine Pulmonary Adenocarcinoma .-Natural history:...
) that acutely transforms the lung epithelia
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
into cancerous cells. Specifically, Type-2 pneumocytes and Clara Cells
Clara cell
Clara cells are dome-shaped cells with short microvilli found in the small airways of the lungs.Clara cells are found in the ciliated simple epithelium...
of the lung are the likely target for JSRV transformation. The tumors formed there exhibit the overactive secretory functions which are a hallmark of OPA.
OPA is an infectious disease of sheep and recently has been used as an animal model for human lung cancer. It is common in the UK and in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. The disease has a long incubation period and is not seen until sheep reach at least 2 years of age. Clinical symptoms include weight loss, loss of appetite, and respiratory difficulty which is associated with obvious movement of the abdomen and high pitched noises. Fluid accumulates in the respiratory tract and the disease ultimately causes death. The retroviral antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
levels of JSRV are very high in OPA tumors and can be detected in the lung secretions of infected sheep. A common field assessment for Jaagsiekte is the "wheelbarrow
Wheelbarrow
A wheelbarrow is a small hand-propelled vehicle, usually with just one wheel, designed to be pushed and guided by a single person using two handles to the rear, or by a sail to push the ancient wheelbarrow by wind. The term "wheelbarrow" is made of two words: "wheel" and "barrow." "Barrow" is a...
test" where one lifts the hind legs of the animal above the head to observe lung exudate
Exudate
An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can apply to plants as well as animals. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as sap or blood...
flow out the nose and mouth. This fluid contains infectious JSRV. It is thought that infected animals secrete the virus before showing clinical symptoms and the virus is therefore easily spread within flocks. The disease is histologically similar to human
Human
Humans are the only living species in the Homo genus...
bronchioalveolar carcinoma which accounts for approximately 25% of all diagnosed human lung cancers.
Dolly the sheep
Dolly the Sheep
Dolly was a female domestic sheep, and the first mammal to be cloned from an adult somatic cell, using the process of nuclear transfer. She was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute near Edinburgh in Scotland...
, the first mammal successfully cloned from an adult somatic cell, was euthanized after it was confirmed that she had Jaagsiekte.