Influenza A Virus in Bats [1]

Influenza A viruses have the potential to cause deadly pandemics and we all assumed that aquatic birds were the major natural reservoir of these influenza A viruses. The recent discovery of two new influenza A viruses in bats suggests that this species may constitute another reservoir with an even greater genetic diversity.

In 2009, a novel Influenza A virus was isolated[1] from little yellow-shouldered bats (Sturnira lilium) in Guatemala. Analysis of the viral genome sequence revealed that Influenza A(H17N10) or A/little yellow-shouldered bat/Guatemala/164/2009 is significantly diverged from all known influenza viruses.

[Little yellow-shouldered bat]

Then news[2] came that a single flat-faced fruit bat (Artibeus planirostris) from Peru tested positive for Influenza A but that also was a previously unknown subtype and it was given the designation Influenza A(H18N11) or A/flat-faced bat/Peru/033/2010.

Next, scientists wanted to know if African straw-coloured fruit bats (Eidolon helvum) would also harbour Influenza A Virus and, sure enough, preliminary results indicate serological evidence against avian influenza subtype H9 in about 30% of the animals screened, with low-level cross-reactivity to phylogenetically closely related subtypes H8 and H12[3].

Can bat influenza A viruses infect humans and serve as a source of future pandemic strains? At this moment the two new bat viruses are not able to infect human cell lines in culture. However, it is entirely possible that acquisition of other (avian, swine or human) influenza virus genes by reassortment could produce a virus with bat influenza virus genes that is capable to infect humans. The pathogenic and pandemic potential of such viruses is currently unknown.

But these findings do indicate that bats constitute a potentially important and likely ancient reservoir for a diverse pool of influenza viruses.

Did I already mention that the Hepatitis B Virus has also been isolated from bats?

[1] Tong et al: A distinct lineage of influenza A virus from bats in Proceedings of the National Academy of Sciences of the USA - 2012
[2] Tong et al: New world bats harbor diverse influenza A viruses in PLoS Pathogens - 2013
[3] Freidl et al: Serological evidence of influenza A viruses in frugivorous bats from Africa in PLoS One - 2015.