Semliki-Forest-Virus

The Semliki Forest virus (SFV ) is a rodent occurring alphavirus of the family Togaviridae, which is transmitted by mosquitoes of the genus Culex as a vector. From these it was first isolated in 1942 in Uganda in adjacent forest areas of the River Semliki.

The genome of SFV is a linear, single-stranded RNA of positive polarity containing two open reading frame for the structural and non- structural proteins. At the 5 ' end of the RNA is a cap structure and the 3'-end, a poly -A tail. Without the flanking terminal portion of the SFV genome comprises 11,442 nucleotides. The two envelope proteins E1 and E2 are linked by transmembrane domains regularly with the icosahedral capsid, so that the virus envelope having a regular structure. The complete virion SFV is about 70 nm in diameter in size, the capsid of about 40 nm and exhibits a symmetry with a Triangulationszahl of T = 4

Biological Properties

The SFV is Eastern, Central and Southern Africa, less common in India and Southeast Asia, where it is transmitted by chronically infected mosquitoes to smaller rodents. Some isolates of SFV can cause encephalitis that is fatal in rodents. Infection can also occur experimentally by aerosols through the nasal mucosa, the natural infection occurs only by insect bites. The SFV is pathogenic for humans produced no characteristic disease. With predominantly asymptomatic gradients may sometimes be a low-grade fever may occur. In only one case a fatal outcome as a result of SFV encephalitis is described in which a highly concentrated cell culture supernatant caused by aerosols in laboratory experiments an unnatural infection. One of the species SFV provisionally assigned Asian subtype is the Me Tri virus whose genome is not fully known and can potentially cause a feverish illness in humans. Due to its relative non-pathogenicity the SFV is used for the production of viral vectors in genetic engineering and gene therapy.