Salamander Influenza-like Virus

We used to think that Influenza viruses only infected vertebrates such as birds and mammals, including humans. However, recent studies have uncovered divergent influenza viruses in amphibians, fish and jawless vertebrates, suggesting that these viruses may be widely distributed.

[Mexican walking fish or axolotl]

Scientists now try to identify additional vertebrate influenza-like viruses and a team from Australia identified the complete coding segments of a divergent vertebrate influenza-like virus[1]. It was a sister lineage to influenza B virus: salamander influenza-like virus in Mexican walking fish or axolotl (Ambystoma mexicanum) and plateau tiger salamander (Ambystoma velasci).

Despite their divergent phylogenetic positions, this virus retained segment conservation and splicing consistent with transcriptional regulation in influenza B virus, and was detected in respiratory tissues.

In addition to the samples infected with salamander influenza-like virus mentioned above, the scientists also identified a smaller number of reads from the Anderson’s salamander (Ambystoma andersoni) and spotted salamander (Ambystoma maculatum) libraries.

These data suggest that influenza viruses have been associated with vertebrates for their entire evolutionary history.

Salamander influenza-like virus appears to be a multi-host virus, being found in four salamander species raised in laboratory colonies, with the greatest abundance in the Mexican walking fish and plateau tiger salamander. While these species have very different life-history strategies, and their ranges do not overlap in nature, both are abundant in the pet trade and used in laboratory research. Thus, breeding facilities may be an important source of these viruses.

[1] Parry et al: Divergent Influenza-Like Viruses of Amphibians and Fish Support an Ancient Evolutionary Association in Viruses – 2020. See here.