Borna disease viruses 1 and 2 | |
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Specialty | Veterinary medicine |
Borna disease virus | |
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Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Negarnaviricota |
Class: | Monjiviricetes |
Order: | Mononegavirales |
Family: | Bornaviridae |
Genus: | Orthobornavirus |
Species: | Mammalian 1 orthobornavirus |
Subtypes | |
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Borna disease, also known as sad horse disease, [1] is an infectious neurological syndrome [2] of warm-blooded animals, caused by Borna disease viruses 1 and 2 (BoDV-1/2). BoDV-1/2 are neurotropic viruses of the species Mammalian 1 orthobornavirus, and members of the Bornaviridae family within the Mononegavirales order.
Borna disease is a severe neurological illness that predominantly affects horses and sheep, but it has been observed in a wide range of mammals. The disease is characterised by ataxia and abnormal depressive behaviour, frequently culminating in death. There have been rare cases of human fatalities associated with encephalitis caused by Borna disease virus infection. [3] Additionally, correlative evidence exists linking BoDV-1/2 infection with neuropsychiatric disorders such as bipolar disorder in humans. [4]
Borna disease was first described in 1885, when all horses belonging to a cavalry regiment stationed near the city of Borna in Saxony, Germany, died from a hitherto unknown disease, then termed hitzige Kopfkrankheit ("hot-tempered head illness"). In 1909, Ernst Joest and Kurt Degen discovered distinctive inclusions in the nerves of horses that had died of Borna disease, which were named Joest-Degen inclusion bodies. [5] This histopathological feature remains in use today to confirm the presence of Borna disease. In 1924, the Austrian virologist Wilhelm Zwick suggested a virus as the cause of the disease.[ citation needed ]
The mode of transmission of BoDV-1/2 is unclear but probably occurs through intranasal exposure to contaminated saliva or nasal secretions. Following infection, individuals may develop Borna disease, or may remain subclinical, possibly acting as a carrier of the virus.[ citation needed ] The only known animal reservoir of BoDV-1 is the bicolored shrew (Crocidura leucodon), which is not susceptible to Borna disease. [6] It is unclear whether human or livestock infections are due to zoonotic transmission from the bicolored shrew.
Borna diseases viruses 1 and 2 appear to have wide host ranges, having been detected in horses, cattle, sheep, new world camelids, dogs, cats, and foxes. [7] [8] In 1995, BoDV-1 was isolated from cats with a "staggering disease" in Sweden. [9] BoDV-1 has been detected in animals in Europe, Asia, Africa and North America.[ citation needed ]
Symptoms of Borna disease in horses and sheep start after a four-week incubation period followed by the development of immune-mediated meningitis and encephalomyelitis.[ citation needed ] Clinical manifestations vary but may include excited or depressed behaviour, ataxia, teeth grinding, excessive salivating, ocular disorders and abnormal posture and movement. Later stages are characterised by bouts of fever and flailing of limbs while lying down. Death occurs a few days to weeks after symptom onset. Mortality rates are 80-100% in horses and greater than 50% in sheep.[ citation needed ]
Experimental infection of rats has been demonstrated to lead to learning impairments and altered social behaviour. The virus appears to be distributed primarily in the limbic system of the brain, including the hippocampus and entorhinal cortex. These areas of the brain are considered to be of importance in emotion.[ citation needed ]
Avian bornaviruses, a group of related viruses, have been reported, yet not proven, as the cause of proventricular dilatation disease (PDD), a disease of pet parrots. The use of a 'positive' brain cell culture containing ABV to inoculate another psittacine (parrot) bird resulted in the inoculated bird's death and subsequent histopathological diagnosis of PDD (mononuclear infiltrative ganglioneuritis). Earlier research with purified avian bornavirus inoculant (while did result in the death of parrots) did not reproduce histopathological changes associated with PDD.[ citation needed ]
Antibodies to BoDV-1 in humans were first discovered in the mid-1980s, suggesting that humans can be non-fatally infected. Antibodies to BoDV-1 and BoDV-1 antigen have also been detected in blood donors.[ citation needed ]
In 2018, three fatal cases of Borna disease in humans were confirmed in Germany. [10] [11] Three people were suspected to have been infected via organ transplants from the same donor, two of whom died. A third fatal case was unconnected to the organ donation. All three deaths were due to severe encephalitis. [10] [11]
In 2020, several additional cases of human infection were identified in the German federal state of Bavaria. [12] In total, there have been 24 cases of confirmed BoDV-1 infection of humans between 1996 and 2021 [ citation needed ]. The infection was almost always fatal. All cases occurred in known areas of spread of BoDV-1, including the federal states of Bavaria, Brandenburg, Thuringia, and Saxony-Anhalt. [3] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [ excessive citations ]
There is some evidence that there may be a relationship between BoDV-1 infection and psychiatric disease. [4] [23]
In 1990, Janice E. Clements and colleagues reported in the journal Science that antibodies to a protein encoded by the BoDV-1 genome are found in the blood of patients with behavioral disorders. [24] In the early 1990s, researchers in Germany, America, and Japan conducted an investigation of 5000 patients with psychiatric disorders and 1000 controls, in which a significantly higher percentage of patients than controls were positive for BoDV-1 antibodies. [24] Subsequent studies have also presented evidence for an association between BoDV-1 and human psychiatric disorders. [25] [26] [27] However, not all researchers consider the link between BoDV-1 and human psychiatric disease to be conclusively proven. A study published in 2003 found no BoDV-1 antibodies in 62 patients with the deficit form of schizophrenia. [28]
Additional evidence for a role of BoDV-1 in psychiatric disorders comes from reports that the drug amantadine, which is used to treat influenza infections, has had some success in treating depression and clearing BoDV-1 infection. [29] [30]
Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.
Bornaviridae is a family of negative-strand RNA viruses in the order Mononegavirales. Horses, sheep, cattle, rodents, birds, reptiles, and humans serve as natural hosts. Diseases associated with bornaviruses include Borna disease, a fatal neurologic disease of mammals restricted to central Europe; and proventricular dilatation disease (PDD) in birds. Bornaviruses may cause encephalitis in mammals like horses or sheep. The family includes 11 species assigned to three genera.
Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include headache, vomiting, fever, confusion and seizures. This occurs about 5 to 15 days after infection.
Nipah virus is a bat-borne, zoonotic virus that causes Nipah virus infection in humans and other animals, a disease with a very high mortality rate (40-75%). Numerous disease outbreaks caused by Nipah virus have occurred in South East Africa and Southeast Asia. Nipah virus belongs to the genus Henipavirus along with the Hendra virus, which has also caused disease outbreaks.
Tick-borne encephalitis (TBE) is a viral infectious disease involving the central nervous system. The disease most often manifests as meningitis, encephalitis or meningoencephalitis. Myelitis and spinal paralysis also occurs. In about one third of cases sequelae, predominantly cognitive dysfunction, persist for a year or more.
Australian bat lyssavirus (ABLV), originally named Pteropid lyssavirus (PLV), is a enzootic virus closely related to the rabies virus. It was first identified in a 5-month-old juvenile black flying fox collected near Ballina in northern New South Wales, Australia, in January 1995 during a national surveillance program for the recently identified Hendra virus. ABLV is the seventh member of the genus Lyssavirus and the only Lyssavirus member present in Australia. ABLV has been categorized to the Phylogroup I of the Lyssaviruses.
Subacute sclerosing panencephalitis (SSPE), also known as Dawson disease, is a rare form of progressive brain inflammation caused by a persistent infection with the measles virus. The condition primarily affects children, teens, and young adults. It has been estimated that about 2 in 10,000 people who get measles will eventually develop SSPE. However, a 2016 study estimated that the rate for unvaccinated infants under 15 months was as high as 1 in 609. No cure for SSPE exists, and the condition is almost always fatal. SSPE should not be confused with acute disseminated encephalomyelitis, which can also be caused by the measles virus, but has a very different timing and course.
Meningoencephalitis, also known as herpes meningoencephalitis, is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain tissue.
Human herpesvirus 6 (HHV-6) is the common collective name for human betaherpesvirus 6A (HHV-6A) and human betaherpesvirus 6B (HHV-6B). These closely related viruses are two of the nine known herpesviruses that have humans as their primary host.
Astroviruses (Astroviridae) are a type of virus that was first discovered in 1975 using electron microscopes following an outbreak of diarrhea in humans. In addition to humans, astroviruses have now been isolated from numerous mammalian animal species and from avian species such as ducks, chickens, and turkey poults. Astroviruses are 28–35 nm diameter, icosahedral viruses that have a characteristic five- or six-pointed star-like surface structure when viewed by electron microscopy. Along with the Picornaviridae and the Caliciviridae, the Astroviridae comprise a third family of nonenveloped viruses whose genome is composed of plus-sense, single-stranded RNA. Astrovirus has a non-segmented, single stranded, positive sense RNA genome within a non-enveloped icosahedral capsid. Human astroviruses have been shown in numerous studies to be an important cause of gastroenteritis in young children worldwide. In animals, Astroviruses also cause infection of the gastrointestinal tract but may also result in encephalitis, hepatitis (avian) and nephritis (avian).
Powassan virus (POWV) is a Flavivirus transmitted by ticks, found in North America and in the Russian Far East. It is named after the town of Powassan, Ontario, where it was identified in a young boy who eventually died from it. It can cause encephalitis, inflammation of the brain. No approved vaccine or antiviral drug exists. Prevention of tick bites is the best precaution.
Limbic encephalitis is a form of encephalitis, a disease characterized by inflammation of the brain. Limbic encephalitis is caused by autoimmunity: an abnormal state where the body produces antibodies against itself. Some cases are associated with cancer and some are not. Although the disease is known as "limbic" encephalitis, it is seldom limited to the limbic system and post-mortem studies usually show involvement of other parts of the brain. The disease was first described by Brierley and others in 1960 as a series of three cases. The link to cancer was first noted in 1968 and confirmed by later investigators.
Antibody-dependent enhancement (ADE), sometimes less precisely called immune enhancement or disease enhancement, is a phenomenon in which binding of a virus to suboptimal antibodies enhances its entry into host cells, followed by its replication. The suboptimal antibodies can result from natural infection or from vaccination. ADE may cause enhanced respiratory disease, but is not limited to respiratory disease. It has been observed in HIV, RSV virus and Dengue virus and is monitored for in vaccine development.
Walter Ian Lipkin is the John Snow Professor of Epidemiology at the Mailman School of Public Health at Columbia University and a professor of Neurology and Pathology at the College of Physicians and Surgeons at Columbia University. He is also director of the Center for Infection and Immunity, an academic laboratory for microbe hunting in acute and chronic diseases. Lipkin is internationally recognized for his work with West Nile virus, SARS and COVID-19.
The Borna disease viruses 1 and 2 are members of the species Mammalian 1 orthobornavirus and cause Borna disease in mammals.
Herpes simplex encephalitis (HSE), or simply herpes encephalitis, is encephalitis due to herpes simplex virus. It is estimated to affect at least 1 in 500,000 individuals per year, and some studies suggest an incidence rate of 5.9 cases per 100,000 live births.
Anti-NMDA receptor encephalitis is a type of brain inflammation caused by antibodies. Early symptoms may include fever, headache, and feeling tired. This is then typically followed by psychosis which presents with false beliefs (delusions) and seeing or hearing things that others do not see or hear (hallucinations). People are also often agitated or confused. Over time, seizures, decreased breathing, and blood pressure and heart rate variability typically occur. In some cases, patients may develop catatonia.
Depression, one of the most commonly diagnosed psychiatric disorders, is being diagnosed in increasing numbers in various segments of the population worldwide. Depression in the United States alone affects 17.6 million Americans each year or 1 in 6 people. Depressed patients are at increased risk of type 2 diabetes, cardiovascular disease and suicide. Within the next twenty years depression is expected to become the second leading cause of disability worldwide and the leading cause in high-income nations, including the United States. In approximately 75% of suicides, the individuals had seen a physician within the prior year before their death, 45–66% within the prior month. About a third of those who died by suicide had contact with mental health services in the prior year, a fifth within the preceding month.
C-type lectin domain family 5 member A (CLEC5A), also known as C-type lectin superfamily member 5 (CLECSF5) and myeloid DAP12-associating lectin 1 (MDL-1) is a C-type lectin that in humans is encoded by the CLEC5A gene.
A Nipah virus infection is a viral infection caused by the Nipah virus. Symptoms from infection vary from none to fever, cough, headache, shortness of breath, and confusion. This may worsen into a coma over a day or two, and 50 to 75% of those infected die. Complications can include inflammation of the brain and seizures following recovery.