Influenza and arthropods

The huge diversity of negative-sense RNA viruses in insects, spiders, ticks and other arthropods suggests that these animals could be central to virus origin and evolution.

Researchers sequenced all of the RNA extracted from 70 arthropod species collected across China. Within this RNA they uncovered the genomes of 112 new negative-sense RNA viruses, and they inferred the evolutionary relationships between the viruses using phylogenetic trees based on the RNA polymerase gene[1]. They found that the 112 new viruses were spread across the major lineages of the negative-sense RNA viruses. These discoveries fill some major gaps in our knowledge, and allow the tree of viral relationships to be updated. For example, this latest work confirms that the viruses of the Arenaviridae genus—which generally infect rodents—belong to the Bunyaviridae family along with two previously unclassified genera of viruses that infect plants[2][3].

This study also raises some exciting new questions. For example, while many of the negative-sense RNA virus lineages were found in the arthropods, some were striking in their absence. Amongst the virus family Orthomyxoviridae, for example, they identified many relatives of the Quaranja viruses, which infect ticks, but none that are closely related to the Influenza viruses that infect vertebrates.

[1] Li et al: Unprecedented genomic diversity of RNA viruses in arthropods reveals the ancestry of negative-sense RNA viruses in eLife – 2015
[2] Ecker et al: The Microbial Rosetta Stone Database: a compilation of global and emerging infectious microorganisms and bioterrorist threat agents in BMC Microbiology – 2005
[3] Kormelink et al: Negative-strand RNA viruses: the plant-infecting counterparts in Virus Research – 2011