Paramyxoviridae

The Paramyxoviridae family includes enveloped viruses with a single-stranded, linear RNA of negative polarity as genome. The Paramyxoviridae family originated from the obsolete taxonomic group of myxoviruses ( gr Myxa: mucus) by definition (Greek para: beside ) from the "real Myxoviruses " ( Orthomyxoviridae ). Among the Paramyxoviridae virus species that affect the respiratory system itself include (eg respiratory syncytial virus of the subfamily Pneumovirinae ) or take him out of their output ( species of the subfamily Paramyxovirinae ). Therefore Paramyxoviridae are not transmitted by vectors and almost exclusively by droplet infection. These are widespread in mammals and birds and important diseases such as distemper and Newcastle disease, in humans there are infections such as measles, mumps and parainfluenza.

Morphology

Virions

The virions of the Paramyxoviridae usually have a round shape and are about 150 nm in diameter in size. Even odd-shaped or thread-like ( filamentous ) forms are described.

Viral envelope

The viral envelope is derived directly from the outer cell membrane (similar to retroviruses ) and surrounds a helical capsid. In the viral envelope 2-3 transmembrane glycoproteins are embedded. Several same membrane proteins self-assemble into oligomers and form so-called spikes of 8-12 nm in length and a distance of 7-10 nm (depending on species ). They form a fusion protein to the outside to penetrate into the cell membrane and a protein to contact (attachment ) to the cell. A non- glycosylated membrane protein is always located at the Paramyxoviridae directed with its main portion inwards and so clothe the shell from the inside out (so-called matrix proteins).

The capsid ( a Ribonukleokapsid ) is 13 to 18 nm thick and can be up to 1000 nm in length depending on the length of the packaged RNA strand in some species. Although you can find because of packaging errors during viral replication and multiple capsids in an envelope, but only a capsid and a strand of RNA per virion is predominantly present. The virion is also always at least one molecule of the viral RNA polymerase and sometimes sections of a complementary ( ) ssRNA.

Genome

The viral genome consists of a single-stranded RNA with negative polarity. The length of the RNA is unusually constant and very similar within the genera. It is about 13 kB ( genus metapneumovirus ) to 18 kB (Genus Henipavirus ), with most paramyxoviruses usually around 15 kB. Considering the length of individual members of the subfamily Paramyxovirinae more closely, this follows an unusual case of virus legality, divisibility by the number 6: eg mumps virus 15,384 nt, Newcastle Disease Virus, 15,156 nt. These multiples of the number 6 are due to a specific mechanism of RNA replication of these viruses.

Biological Properties

The Paramyxoviridae can infect mammals and birds. There are not yet classified, but the paramyxoviruses related viruses in fish ( salmon of the genus Oncorhynchus ), and reptiles. In the multiplication Paramyxoviridae dissolve the cell and are thus cytolytic. The individual virus species are very closely matched to their respective host and therefore can hardly be transmitted from one host species to another. Paramyxoviridae usually cause acute and self-limited infection, which is eliminated by an unimpaired immune system of the host again. A chronic or persistent infection is a special case only when measles virus ( as Subacute sclerosing panencephalitis ) and the canine distemper virus described ( in dogs Erregerpersistenz and excretion months).

System

  • Family Paramyxoviridae
  • Subfamily Paramyxovirinae
  • Genus Rubulavirus
  • Genus Avulavirus
  • Genus Respirovirus
  • Genus Henipavirus
  • Genus Morbillivirus
  • Subfamily Pneumovirinae
  • Genus pneumovirus
  • Genus metapneumovirus

In addition to the unclassified species comprising the family Paramyxoviridae more, nor any genus associated species:

  • Fer -de- Lance virus ( Host: Reptiles )
  • Nariva virus ( Host: Rodents )
  • Salem virus
  • Tupaia paramyxovirus ( Host: Tupaia belangeri )
  • Beilong virus
  • J virus
  • Menangle virus
  • Mossmann virus
  • Murayama virus
  • Paramyxovirus of Pacific salmon
  • Reptiles paramyxovirus
  • Snake paramyxovirus ( ATCC VR - 1408, and ATCC VR -1409 )
  • Tioman virus
Mononegavirales Virus classification National Center for Biotechnology Information Human parainfluenza viruses Virus#Etymology RNA-Polymerase Journal of Virology
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