Phleboviruses

Rift Valley Fever virus

Phlebovirus (Phleboviridae) is one of five genre of the family Bunyaviridae. Its members are class V virus with segmented ambisense RNA genomes. Due to their need for self coded reverse transcriptase, there are two rounds of replication, one before the production of reverse transcriptase and one after it production.

The genome comprises 3 segments, two of which are ambisense. The small segment (S) codes for the viral N protein and a non structural protein. The medium sized segment (M) codes for a precursor of the viral glycoprotein; non-structural components. The product of the largest segment is an RNA polymerase.

Phleboviridae currently has 68 antigenically distinct virus serotypes, only a few of which have been studied. Of these 68 serotypes, eight of them have been linked to disease in humans, they are: Alenquer, Candiru, Chagres, sandfly fever Naples, sandfly fever Punta Toro, Rift Valley fever, sandfly fever Sicilian and sandfly fever Toscana.

The 68 known serotypes are divided into two groups; the Phlebotomus fever viruses (sandfly group) are transmitted by sandflies and comprise 55 members and the Uukuniemi group (transmitted by ticks) having 13 members.

They cause symptoms ranging from short self limiting fevers to encephalitis and fatal haemorrhagic fever.