Wolbachia Genomes Evolve Rapidly in Mosquito Cell Culture

Wolbachia, bacterial symbionts widespread among arthropods, can evolve measurably within months when grown in mosquito cell culture, according to a new study by Julien Martinez, Anne W. Wairimu and Steven P. Sinkins. The researchers introduced five Wolbachia strains originally from Drosophila into the symbiont-free Aedes albopictus Aa23 cell line and tracked genomic change using long-read whole-genome sequencing.

Wolbachia are of intense practical interest because they manipulate host reproduction and can protect insects against viral pathogens. Their ability to spread through mosquito populations, combined with their antiviral effect, underpins health programmes that deploy Wolbachia-infected Aedes mosquitoes to curb dengue virus transmission. Understanding how these bacteria evolve over short timescales is therefore directly relevant to the durability of such interventions.

After transinfection, sequencing revealed multiple mutations in the Wolbachia genomes, including structural changes. Some of these mutations were associated with major shifts in bacterial density, a trait central to how Wolbachia spreads within hosts and populations and how strongly it blocks viruses.

Several lines of evidence pointed to selection as the dominant evolutionary force. The researchers observed signs of convergent evolution, meaning similar changes appeared repeatedly, alongside an excess of non-synonymous mutations that alter proteins. Comparisons with previous studies further indicated that Wolbachia evolution in cell culture proceeds faster than it does in insect hosts.

The authors argue that cell culture offers a valuable experimental platform for studying short-term symbiont evolution, probing the genetic basis of bacterial density regulation, and generating higher-density Wolbachia strains that could be better suited to disease control. Because the findings come from an in vitro system, they illuminate evolutionary dynamics under laboratory conditions rather than directly in field mosquito populations, but they suggest experimental evolution could help breed novel symbiont strains with improved properties for future Wolbachia-based interventions.

Subject of Research: Rapid, convergent evolution of Wolbachia bacterial symbionts in mosquito cell culture

Article Title: Rapid and convergent evolution of Wolbachia genomes in mosquito cell culture

Article References: Martinez, J., Wairimu, A. W., & Sinkins, S. P. (2026). Rapid and convergent evolution of Wolbachia genomes in mosquito cell culture. PLOS Pathogens, 22(10), e1014735. https://doi.org/10.1371/journal.ppat.1014735

Image Credits: AI Generated

DOI: 10.1371/journal.ppat.1014735

Keywords: Wolbachia, Aedes albopictus, cell culture, experimental evolution, symbiont density, dengue, mosquito, genome sequencing, transinfection, convergent evolution, bacterial symbiosis, disease control