Breaking down the microbiology world one bite at a time
Fighting Microbe With Microbe: the Power of Wolbachia.
When you think about what you need to fight off an infection, the first thing that likely comes to mind is some kind of antibiotic. To much surprise, humans didn’t create antibiotics. We took the medicine from bacteria that naturally produce it and adapted it to treat deadly infections. Who knew that bacteria are (sometimes) the good guys?
Bacteria are more often heroes than villains in the story of life. We are covered in bacteria, from the skin on our hands to the deep folds of our gastrointestinal tract. The human microbiome frequently lends a hand when we’re trying to digest food, strengthen our immune systems, and combat infectious diseases. Bacteria often share similar forms of symbiosis with other organisms. Even insects harbor bacteria, and it wasn’t until recently that scientists discovered the unique power of one particular insect-bacteria mutualistic relationship.
Introducing what seems like an uninteresting bacterium: Wolbachia pipientis.
Wolbachia is widespread among insects, including some of the pesky mosquitoes you find during the summer. Scientists took no notice of Wolbachia in insects for decades following its original discovery in the early 1900s (1). It wasn’t until a few decades ago that researchers discovered the surprising prevalence of Wolbachia among insect populations. Wolbachia was initially found to act as a parasite in some insects by manipulating their reproductive cycles in order to persist in the insect population.
Over time, researchers discovered an interesting feature of Wolbachia: the bacterium protects the bug from certain viruses (2). It wasn’t long before scientists realized the full potential of Wolbachia as a way to combat vector-borne diseases or viral diseases spread by insects and other vectors.
Vector-borne diseases are a significant problem around the world and often challenging to eradicate. Serious infectious diseases such as malaria, Zika, and dengue are transmitted by mosquitoes that spread the viruses at alarming rates (3). Treatment and vaccinations are sparse or far from perfect, which motivates researchers to find more creative solutions to control and prevent the spread of the diseases.
Research on Wolbachia in insects like fruit flies and mosquitoes revealed that those with the bacterium were able to prevent certain viruses from replicating and thus reduce disease burden in the insect (2). Since Wolbachia has clever ways of spreading throughout the insect populations, scientists started looking for ways to use the bacterium to combat the spread of disease by targeting the vector rather than the virus directly (Figure 2) (4).
A recent paper by Dr. Adi Utarini and others tested the power of Wolbachia in a large-scale field study (5). They infected dengue-susceptible mosquitoes with Wolbachia and released them into the Yogyakarta community in Indonesia to see if the bacterium reduced the spread of dengue. Utarini and her team broke up the Yogyakarta region into clusters: 12 received mosquitoes infected with Wolbachia, and 12 had no deployment of mosquitoes. After the team released the Wolbachia-infected mosquitoes into the assigned clusters, they worked with the region’s health clinics to record the number of new cases of dengue from each cluster over a two-year period.
This intelligently-designed trial revealed that the presence of Wolbachia in mosquito populations reduced the number of new dengue cases by 77% compared to the clusters that did not receive the mosquitoes. This treatment of mosquitoes significantly lowered the overall number of hospitalizations in the community and even showed impressive efficacy against multiple strains of the dengue virus. Wolbachia poses no threat to humans and is easily maintained in mosquito populations, making the bacterium an effective weapon against not only dengue but other deadly viruses like Zika.
Thanks to the power of Wolbachia and other beneficial bacteria, humans are better equipped to combat deadly infectious diseases that continue to plague the Earth.
- Burki T. (2020). Wolbachia, a bacterium fighting on our side. The Lancet. Infectious diseases, 20(6), 662–663. https://doi.org/10.1016/S1473-3099(20)30384-4
- Pimentel AC, Cesar CS, Martins M and Cogni R (2021) The Antiviral Effects of the Symbiont Bacteria Wolbachia in Insects. Front. Immunol. 11:626329. doi: 10.3389/fimmu.2020.626329
- World Health Organization. Vector-borne diseases (2020). https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases
- McGraw, E., O’Neill, S. (2013). Beyond insecticides: new thinking on an ancient problem. Nat Rev Microbiol 11, 181–193. https://doi.org/10.1038/nrmicro2968
- Utarini, A., et al. (2021). Efficacy of Wolbachia-infected mosquito deployments for the control of dengue. N Engl J Med 384, 2177-86. DOI: 10.1056/NEJMoa2030243
Featured image: Created in Biorender