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Neurovirulence
A neurotropic virus is a virus that is capable of infecting nerve tissue. Terminology A neurotropic virus is said to be neuroinvasive if it is capable of accessing or entering the nervous system and neurovirulent if it is capable of causing disease within the nervous system. Both terms are often applied to central nervous system infections, although some neurotropic viruses are highly neuroinvasive for the peripheral nervous system (e.g. herpes simplex virus). Important neuroinvasive viruses include poliovirus, which is highly neurovirulent but weakly neuroinvasive, and rabies virus, which is highly neurovirulent but requires tissue trauma (often resulting from an animal bite) to become neuroinvasive. Using these definitions, herpes simplex virus is highly neuroinvasive for the peripheral nervous system and rarely neuroinvasive for the central nervous system, but in the latter case may cause herpesviral encephalitis and is therefore considered highly neurovirulent. Many arthropo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 of an RNA genome and a protein capsid. The genome is a single-stranded positive-sense RNA (+ssRNA) genome that is about 7500 nucleotides long. The viral particle is about 30 nm in diameter with icosahedral symmetry. Because of its short genome and its simple composition—only a strand of RNA and a nonenveloped icosahedral protein coat encapsulating it—poliovirus is widely regarded as the simplest significant virus. Poliovirus is one of the most well-characterized viruses, and has become a useful model system for understanding the biology of RNA viruses. Replication cycle Poliovirus infects human cells by binding to an immunoglobulin-like receptor, CD155 (also known as the poliovirus receptor or PVR) on the cell surface. Inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 16,000 of the millions of List of virus species, virus species have been described in detail. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent viral particles, or ''virions'', consisting of (i) genetic material, i.e., long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polio
Poliomyelitis ( ), commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 75% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe symptoms develop such as headache, neck stiffness, and paresthesia. These symptoms usually pass within one or two weeks. A less common symptom is permanent Flaccid paralysis, paralysis, and possible death in extreme cases.. Years after recovery, post-polio syndrome may occur, with a slow development of muscle weakness similar to what the person had during the initial infection. Polio occurs naturally only in humans. It is highly infectious, and is spread from person to person either through fecal–oral route, fecal–oral transmission (e.g. poor hygiene, or by ingestion of food or water contaminated by human feces), or via the oral–oral route. Those who are infected may spread the disease for up to six weeks even if no symptoms are pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Signs and symptoms may appear in as little as two days after exposure to the virus. These may include coughing, sore throat, rhinorrhea, runny nose, Sneeze, sneezing, headache, fatigue, and fever. People usually recover in seven to ten days, but some symptoms may last up to three weeks. Occasionally, those with other health problems may develop pneumonia. Well over 200 virus strains are implicated in causing the common cold, with rhinoviruses, coronaviruses, Adenoviridae, adenoviruses and enteroviruses being the most common. They spread through the air or indirectly through contact with objects in the environment, followed by transfer to the mouth or nose. Risk factors include going to child care facilities, Sleep deprivation, not sleepin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS and COVID-19. In cows and pigs they cause diarrhea, while in mice they cause hepatitis and encephalomyelitis. Coronaviruses constitute the subfamily ''Orthocoronavirinae'', in the family ''Coronaviridae'', order ''Nidovirales'' and realm ''Riboviria''. They are enveloped viruses with a Positive-strand RNA virus, positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 26 to 32 kilobases, one of the largest among RNA viruses. They have characteristic club-shaped Spike protein, spikes that project from their surface, which in electron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HHV-6
Human herpesvirus 6 (HHV-6) is the common collective name for human herpesvirus 6A (HHV-6A) and human herpesvirus 6B (HHV-6B). These closely related viruses are two of the nine known herpesviruses that have humans as their primary host. HHV-6A and HHV-6B are double-stranded DNA viruses within the ''Betaherpesvirinae'' subfamily and of the genus '' Roseolovirus''. HHV-6A and HHV-6B infect almost all of the human populations that have been tested. HHV-6A has been described as more neurovirulent, and as such is more frequently found in patients with neuroinflammatory diseases such as multiple sclerosis. HHV-6 (and HHV-7) levels in the brain are also elevated in people with Alzheimer's disease. HHV-6B primary infection is the cause of the common childhood illness exanthema subitum (also known as roseola infantum or sixth disease). It is passed on from child to child. It is uncommon for adults to contract this disease as most people have had it by kindergarten, and once contract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytomegalovirus
''Cytomegalovirus'' (CMV) (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order '' Herpesvirales'', in the family '' Herpesviridae'', in the subfamily '' Betaherpesvirinae''. Humans and other primates serve as natural hosts. The 11 species in this genus include '' human betaherpesvirus 5'' (HCMV, human cytomegalovirus, HHV-5), which is the species that infects humans. Diseases associated with HHV-5 include mononucleosis and pneumonia, and congenital CMV in infants can lead to deafness and ambulatory problems. In the medical literature, most mentions of CMV without further specification refer implicitly to human CMV. Human CMV is the most studied of all cytomegaloviruses. MX2/MXB protein was identified as a restriction factor for herpesviruses, which acts at a very early stage of the replication cycle and MX2/MXB restriction of herpesvirus requires GTPase activity. Taxonomy Within the '' Her ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varicella-zoster
Varicella zoster virus (VZV), also known as human herpesvirus 3 (HHV-3, HHV3), is one of nine known herpes viruses that can infect humans. It causes chickenpox (varicella) commonly affecting children and young adults, and shingles (herpes zoster) in adults but rarely in children. As a late complication of VZV infection, Ramsay Hunt syndrome type 2 may develop in rare cases. VZV infections are species-specific to humans. The virus can survive in external environments for a few hours. VZV multiplies in the tonsils, and causes a wide variety of symptoms. Similar to the herpes simplex viruses, after primary infection with VZV (chickenpox), the virus lies dormant in neurons, including the cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia. Many years after the person has recovered from initial chickenpox infection, VZV can ''reactivate'' to cause shingles. Epidemiology Chickenpox Primary varicella zoster virus infection results in chickenpox (varicella), which ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herpesviridae
''Orthoherpesviridae'', previously named and more widely known as ''Herpesviridae'', is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are commonly known as herpesviruses. The family name is derived from the Greek word ἕρπειν ( 'to creep'), referring to spreading cutaneous lesions, usually involving blisters, seen in flares of herpes simplex 1, herpes simplex 2 and herpes zoster ( shingles). In 1971, the International Committee on the Taxonomy of Viruses (ICTV) established ''Herpesvirus'' as a genus with 23 viruses among four groups. Since then, the number of identified herpesviruses has grown to more than 100. Herpesviruses can cause both latent and lytic infections. Nine herpesvirus types are known to primarily infect humans, at least five of which are extremely widespread among most human populations, and which cause common diseases: herpes simplex 1 and 2 (HSV-1 and HSV-2, also know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rabies
Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abnormal sensations at the site of exposure. These symptoms are followed by one or more of the following symptoms: nausea, vomiting, violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness. Once symptoms appear, the result is virtually always death. The time period between contracting the disease and the start of symptoms is usually one to three months but can vary from less than one week to more than one year. The time depends on the distance the virus must travel along Peripheral nervous system, peripheral nerves to reach the central nervous system. Rabies is caused by lyssaviruses, including the rabies virus and Australian bat lyssavirus. It is spread when an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza
Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin one to four (typically two) days after exposure to the virus and last for about two to eight days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia from the virus or a subsequent bacterial infection. Other complications include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease. There are four types of influenza virus: types A, B, C, and D. Aquatic birds are the primary source of influenza A virus (IAV), which is also widespread in various mammals, including humans and pigs. Influenza B virus (IBV) and influenza C virus (ICV) primarily infect humans, and influenza D virus (IDV) i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
