Ljungan virus was first discovered in the mid-1990s after being isolated from a

bank vole The bank vole (''Clethrionomys glareolus'') is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in much of Eu ...

near the

Ljungan Ljungan ( Jamtlandic: ''Jångna'' or ''Aoa'', from Old Norse ''*Oghn'' "the dreadful") is a 322 kilometer long river in Sweden. It originates near Trondheim and the Norwegian border. The river runs through the Swedish counties of Jämtland and ...

river in

Medelpad Medelpad ( or ) is a historical province or ''landskap'' in the north of Sweden. It borders Hälsingland, Härjedalen, Jämtland, Ångermanland and the Gulf of Bothnia. The province is a part of Norrland and as such considered to be Northe ...

county,

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

. It has since been established that Ljungan virus, which is also found in several places in Europe and America, causes serious illness in

wild Wild, wild, wilds or wild may refer to: Common meanings * Wilderness, a wild natural environment * Wildlife, an undomesticated organism * Wildness, the quality of being wild or untamed Art, media and entertainment Film and television * ''Wild ...

as well as

laboratory animal Animal testing, also known as animal experimentation, animal research, and ''in vivo'' testing, is the use of animals, as model organisms, in experiments that seek answers to scientific and medical questions. This approach can be contrasted ...

s. Several scientific articles have recently reported findings indicating that Ljungan virus is associated with

malformation A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

s, intrauterine fetal death, and

sudden infant death syndrome Sudden infant death syndrome (SIDS), sometimes known as cot death or crib death, is the sudden unexplained death of a child of less than one year of age. Diagnosis requires that the death remain unexplained even after a thorough autopsy and ...

in humans. In addition, studies are being conducted worldwide to investigate the possible connection of the virus to

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

neurological Neurology (from , "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the s ...

and other illnesses in humans. Ljungan virus belongs to the genus ''Parechovirus'' of the family ''Picornaviridae''. Other members of this viral family include

poliovirus Poliovirus, the causative agent of polio (also known as poliomyelitis), is a serotype of the species '' Enterovirus C'', in the family of '' Picornaviridae''. There are three poliovirus serotypes, numbered 1, 2, and 3. Poliovirus is composed ...

Hepatitis A virus Hepatitis A is an infectious liver disease caused by Hepatitis A virus (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop them, is ...

, and the viruses that cause the

common cold The common cold, or the cold, is a virus, viral infectious disease of the upper respiratory tract that primarily affects the Respiratory epithelium, respiratory mucosa of the human nose, nose, throat, Paranasal sinuses, sinuses, and larynx. ...

(

rhinovirus The rhinovirus (from the "nose", , romanized: "of the nose", and the ) is a Positive-sense single stranded RNA virus, positive-sense, single-stranded RNA virus belonging to the genus ''Enterovirus'' in the family ''Picornaviridae''. Rhinoviru ...

). One of the earliest scientific discoveries regarding Ljungan virus was that infected wild rodents developed diabetes if they were exposed to stress. This has led to speculation that this disease may be the underlying cause of fluctuating rodent populations in

Scandinavia Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...

; when rodents increase to high densities, they find it difficult to defend territory and obtain food, and then become more susceptible to predation. This stressful situation results in disease, death and population decline, leading to a pattern of cyclic variation in population size over time.

Viral classification

Ljungan virus is a positive sense, single stranded RNA virus. Ljungan virus is a virus that contains an outer shell. This outer shell, or capsid is made up of proteins set up in an icosahedral formation. Unlike other picornaviruses, the capsid shell of Ljungan virus has some proteins that protrude and are markedly displaced from the remainder of the proteins. Pentakis icosidodecahedron

Genome replication

Cell entry

There is a receptor for Ljungan virus on the outer membrane of a cell called

integrin Integrins are transmembrane receptors that help cell–cell and cell–extracellular matrix (ECM) adhesion. Upon ligand binding, integrins activate signal transduction pathways that mediate cellular signals such as regulation of the cell cycle, o ...

α_vβ₆. The viral Protein RGD is what binds the virus to the cell it is trying to get into. The protein rests in the more flexible areas of the capsid shell. Very little is known about how exactly the virus enters the cell. The virus can enter the cell through many different pathways, but most likely the

α_vβ₆ proteins on the host cell are still used.

Replication

When the virus is replicating in cells, it typically uses the mechanisms already in the cell to replicate ins own genomic information. However, unlike many other picornaviruses, Ljungan virus does not completely shut down the host cell's ability to replicate its own genomic information. Protein synthesis is maintained and not disrupted in the host cell. Maintaining protein synthesis allows the virus to prevent normal cellular replication, but still allow for ribosome dependent translation to occur. The primary site for replication is also thought to be in the gastrointestinal and respiratory tracts.

Associated diseases

Due to primary replication in the gastrointestinal tract, specifically the intestines, viral shedding can lead to many gastrointestinal issues. Diarrhea is one of the most common symptoms associated with being infected with picornaviruses, Ljungan virus included. As for respiratory disease and symptoms, there is evidence that Ljungan virus can cause respiratory disease. Wheezing and even contracting

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

have also been identified as symptoms of respiratory infection with Ljungan virus.

References

External links

Ljunganvirus.org
– This site intends to be a knowledge bank summarizing the increasing mass of information generated regarding the effects of Ljungan virus infection. It is financed and written by Apodemus AB. * – Apodemus is the research company that discovered Ljungan virus in the 1990s {{DEFAULTSORT:Ljungan virus Picornaviridae Rare diseases Rare infectious diseases Rodent diseases