Akabane-Virus
The Akabane virus is a occurring in cows, goats and sheep virus species in the genus Orthobunyavirus. It was the first time in 1959 in Akabane (Japan) isolated from mosquitoes of the species Aedes vexans and Culex tritaeniorhynchus. The virus is transmitted by various mosquitoes and biting midges (Bart mosquitoes ) and usually causes only mild febrile disease in various ruminant. However, in the case of a pregnancy occurs via the placenta to transfer to the fetus, where it causes severe birth defects and disorders of the central nervous system. Frequently it comes to abortion.
As Schmallenberg virus ( SBV) is referred to a the Akabane virus very closely related virus that was detected in infected cattle in Germany 2011.
Virus morphology and genome
The Akabane virus is 90 to 100 nm in diameter in size and round in shape. The viral envelope contains embedded envelope proteins that appear morphologically as Peplomere. The envelope encloses three different sizes, helical capsids with one strand of the segmented RNA genome. The three genomic segments (L, M and S) are composed of a single-stranded RNA with negative polarity. The large segment (L, large: 6870 nt) coding for the viral RNA polymerase, the middle (M, medium: 4310 nt ) for two glycoproteins of the viral envelope and the small (S, small: 860 nt) for the nucleoprotein of the capsids. Each segment also contains a non-coding section.
The virus is heat labile and is inactivated at 56 ° C in a few minutes. At 37 ° C loses about 0.3 logs per hour of its infectivity. It shows no acid resistance and may be inactivated by conventional detergents, and alcohol-based disinfectants.
Distribution and hosts
The Akabane virus has been isolated from cattle, sheep and goats. Antibodies against the virus (but not the virus itself ) are also detected in pigs, horses, camels, deer, hippos, elephants, giraffes, antelopes and other ungulates in Africa. Although the virus -transmitting mosquitoes also bite humans, no disease is known by the Akabane virus in humans. The virus is also prevalent endemic in Africa, the Middle East, South Asia, Japan, Korea and Australia. The occurrence of the disease is closely related to the occurrence and seasonal activity of the transmitting mosquitoes. As vectors, different mosquito species of the genera Culex, Aedes and Anopheles were identified. The virus is taken up by the blood meal of the mosquito and multiplies there in the salivary glands. A vertical transmission in the mosquito eggs ( transovarial transmission ) could not be found.
European isolates
In November 2011, the Friedrich- Loeffler- Institute announced that one could isolate a the Akabane virus very closely related virus in infected cattle in Germany, which is tentatively named after the site of the first sample origin, as Schmallenberg Schmallenberg virus. On the basis of the sequence is also a relationship to Aino virus and Shamonda virus isolates. It is still unclear whether it is a subspecies of the Akabane virus or to an independent species of the genus Orthobunyavirus.
The new isolate was found as part of a wave of illness in cattle in North Rhine- Westphalia, where there was an accumulation of fever, drop in milk yield and loss of appetite at about 80 animals since the summer of 2011. Shortly before these symptoms also showed in cattle in the Netherlands. It is unclear whether the virus is already circulating in Europe or whether it was re-registered. It is the first case of a disease events in animals in Europe isolated bunyavirus.
In the following months occurred in the Netherlands, Belgium and Germany in the federal states of North Rhine -Westphalia, Lower Saxony and Hesse increasingly malformed lambs on where the Schmallenberg virus could be detected in the brain. The type of malformations indicate an infection of the already -bearing ewes in the summer or fall of 2011. As of March 23, 2012, the virus was detected in animals from 1061 farms in Germany. Since March 30, 2012, a reporting requirement in Germany.
As intermediaries Fly come from the family of biting midges, Culicoides obsoletus particular, Culicoides dewulfi and Culicoides pulicaris, considered, in which the pathogen was detected.
System
- Genus Orthobunyavirus Species Akabane virus Subspecies Sabo virus
- Subspecies Tinaroo virus ( TINV )
- Subspecies Yaba -7 virus
Swell
- P. S. Mellor, P. D. Kirkland: Akabane virus. In: Brian WJ Mahy and Marc H. van Regenmortel (eds. ): Encyclopedia of Virology, 3rd Edition, San Diego 2008, Volume 1, ISBN 978-0-12-373935-3, pp. 76-80