In the hunt for new organisms, sometimes you just get lucky. The authors of a paper in mBio this week found a virus that offered two discoveries for the price of one: it’s a novel organism that also reveals lessons in evolutionary ecology.
The Cavally virus (CAVV) is the first known insect-associated nidovirus. Discovered in about 9% of mosquitoes sampled within and around a primary forest habitat in Ivory Coast, it apparently represents a new family of viruses: based on the morphology of the virus, its conserved genome motifs and its phylogenetic relationships to other nidoviruses, Zirkel et al. identify CAVV as the first representative of a family of nidoviruses that is distinct from the established Arteriviridae, Roniviridae and Coronaviridae families. No other nidoviruses are known to live in an insect host, but animals that host nidoviruses, including bats and certain birds, are often insectivorous.
And the lessons in evolutionary ecology? In a population study of CAVV in its natural habitat, the authors isolated the virus from several species of mosquitoes and tracked its prevalence and genomic diversity across a gradient of environmental disturbance, ranging from undisturbed primary forest to plantations and human settlements. The virus was found in all habitat types, and as disturbance increased, so did the prevalence of the virus: the virus was most prevalent in human settlements. Diversity, however, declined with disturbance, indicating a reverse dilution effect at work. Further research is needed to determine whether the higher prevalence of the virus in human settlements is due to a greater density of insect of vertebrate hosts or to virus adaptation to those habitats.