Picorna virus is small (20 to 30 nm), has no envelope, contains single-stranded RNA genome (MW 2-3 × 10 ^ 6). Nucleocapsid has three-dimensional symmetry and contains 32 spherical subunits (capsomeres). Viral maturation occurs in the cytoplasm. Enteroviruses and rhinoviruses generally infect humans.
Enterovirus
Enteroviruses are present in many animals, including humans, cows, pigs, and mice. Enteroviruses of human origin include the following:
- Poliovirus, type 1 to 3
- Group A coxsackie virus, type 1-24
- Group B Coxsackie virus, type 1-6
- Enterovirus type 68-71.
Enteroviruses are temporary residents of the human gastrointestinal tract and can be isolated from the throat or lower intestine. Rhinovirus, on the other hand, is isolated primarily from the nose and throat. In primary cultures of human and monkey kidney cells and certain cell lines (such as HeLa) among the enteropathogenic enteroviruses (poliovirus, echovirus, and some coxsackie viruses) easily propagated at 36-37 ° C. Is obtained. In contrast, most rhinovirus strains can be recovered only at 33 degrees Celsius in cells of human origin (embryonic human kidney or lung, human diploid cell line).
Enterovirus capsids are believed to consist of 32 morphologic subunits possible in the form of rhombic icosahedrons, not regular cubes. The structure of the rhinovirus capsid appears to be similar. Infectious nucleic acids are extracted from several enteroviruses and rhinoviruses. Enteroviruses and rhinoviruses have different buoyant densities. Enteroviruses have a buoyant density at about 1.34 g / mL CsCl. It is about 1.40 g / mL human rhinovirus. Three of the first enumerated enteroviruses are the most common, but affecting human health is less common. We can quit and see what it is.
Enterovirus type 68-71
Four enteroviruses (type 68-71) grow in monkey kidney cultures, and three cause human disease. Enteroviruse 68 was isolated from the respiratory tract of children with bronchitis or pneumonia. Enterovirus 70 is a major cause of acute hemorrhagic conjunctivitis. Acute hemorrhagic conjunctivitis suddenly occurs suddenly in the subconjunctival bleeding from a nodule to a large spot covering the conjunctival conjunctiva. Epithelial keratitis and occasional lumbar myelomyelitis may also be present. This disease is most common in adults and has a duration of incubation day and a duration of 8 to 10 days. Full recovery is the principle. This virus is highly contagious and rapidly spreads under crowded or unsanitary conditions. There is no effective treatment.
Enterovirus 71 was isolated from patients with meningitis, encephalitis, and paralysis similar to paralysis. It continues to be one of the leading causes of central nervous system diseases worldwide, sometimes lethal. In some areas, especially in Japan and Sweden, this virus is causing an outbreak of limbs and mouth disease.
Rhinovirus
Human rhinovirus contains over 100 antigenic forms. Rhinoviruses of other host species include horse and bovine rhinoviruses.
Other General
Other picornaviruses are bovine foot and mouth disease (aflatoxins) and rodent encephalomyocarditis (cardiovirus). The host range of picornavirus varies greatly from one type to the next and even between strains of the same type. They can still be induced by laboratory manipulation to produce variants with different host range and tissue tropism than specific wild type strains; this is still due to the presence of attenuated poliovirus strains currently in use as vaccines It led to development.
