Upolu Virus

The Upolu Virus belongs to the Thogotoviruses and that makes it a direct relative of the influenza viruses because all are part of the larger family of Orthomyxoviruses. The genus Togotoviruses has nine distinct members: Thogoto Virus, Dhori Virus, Araguari Virus, Batken Virus, Jos Virus, Upolu Virus, Aransas Bay Virus, Bourbon Virus and Sinu Virus.

Upolu virus was first isolated in 1966 from adult Ornithodoros capensis ticks that infested a sooty tern (Sterna fuscata) colony on Upolu Cay, a small atoll that is part of the Great Barrier Reef, Australia[1].

For a long time, Upolu Virus was thought to be an unassigned virus in the family Bunyaviridae. Antibodies have later been found in cattle and kangaroo on the Australian mainland.

[Upolu Cay]

Then, researchers reported the identification of two previously unrecognized members of the family Orthomyxoviridae[2], which includes the influenza viruses and the tick-transmitted Thogoto and Dhori viruses. The report provided evidence that both Upolu Virus from Australia and Aransas Bay Virus from North America are orthomyxoviruses.

[Sooty tern]

Both viruses genomes show a fairly close nucleotide sequence conservation to Thogoto Virus and Jos Virus (68%) and a somewhat more distant relationship to Dhori virus. It shares about 20% of its genes with Influenza viruses.

Which means that the ever expanding family of Influenza-related viruses has two new members. A curious fact is that Upolu Virus and Aransas Bay Virus were discovered half a world apart. One possible explanation for this extensive distribution of this family of viruses associated with Ornithodoros capensis ticks is the fact that many of its primary hosts, such as terns, migrate for great distances.

As yet, there are no reports that Upolu Virus is capable of causing disease in humans.

[1] Doherty et al: Isolation of viruses from Ornithodoros capensis Neumann from a tern colony on the Great Barrier Reef, North Queensland in Australian Journal of Science - 1968
[2] Briese et al: Upolu virus and Aransas Bay virus, two presumptive bunyaviruses, are novel members of the family Orthomyxoviridae in Journal of Virology - 2014