#FEMSmicroBlog: Galleria mellonella - science's next top model

23-07-2022

The National Moth Week celebrates the beauty, life cycles and habitats of moths. Especially the Greater Wax moth, Galleria mellonella, is attracting increasing research interest, with publications on Galleria having increased ∼10-fold in the last 10 years. Hue Dinh, Hannah Lott and Amy Cain explain for the #FEMSmicroBlog, why many microbiologists employ Galleria larvae more and more for their research purposes. #MicrobiologyEvents

 

Galleria and its rise to fame

For much of its natural history, Galleria was viewed as merely a beehive pest. However, recently it has been recast in a new light: as a highly effective and adaptable ethical animal model.

Over the last decade, Galleria larvae have been increasingly employed by scientists for a multitude of uses, not only in microbiology but also in the chemical sciences. The Galleria model offers more research-saving advantages than the better-known laboratory mouse while it has some unique bonus features.

Galleria larvae are well-suited for high-throughput screening of chemical compounds and virulence testing of pathogens.
Galleria larvae.

Galleria as a research model presents fewer ethical concerns than rodents since they perfectly align with the animal ethics policy of ‘replace, reduce and refine’. Using Galleria as an animal model instead of mammals overcomes many hurdles associated with traditional animal studies, such as a costly infrastructure, specialist training and daunting maintenance bills – thereby making in vivo studies more accessible. To recognise Galleria’s desirable attributes, we recently authored the in-depth review “Microbiology’s next top model: Galleria in the molecular agein Pathogens and Disease.

Galleria mellonella has many ethical advantages, low maintenance costs, rapid reproduction time, innate immune system and similarities to mammalian host models.

 

Galleria as an ideal host for microbiological studies

In microbiological studies, Galleria is being widely used to assess the pathogenicity of microorganisms. For this purpose, Galleria larvae are injected with a pathogen of interest and their survival and health are monitored. This helps microbiologists determine whether a newly isolated species would be a friend or foe to humans.

Injecting compounds of interest into Galleria larvae.

Using the Galleria Health Index Scoring System, researchers can draw conclusions by tracking the movement, cocoon formation, survival and colour of the larvae. Galleria makes it easy to determine how dangerous a bacterium is via the process of melanisation. By following the different darkening stages, one can get a visual indication of the health of the larvae and thus the impact of the injected microbe.

Different stages of larval health with dark brown indicating high microbial virulence.
Different stages of larval health with dark brown indicating high microbial virulence.

Galleria is also a suitable platform for understanding gene function and changes at the molecular level during infection. For example, a recent study (currently under review) tested the function of a single gene by injecting Galleria with a bacterial strain harbouring a disabled gene of interest. This work characterised an important virulence-related gene in Acinetobacter baumannii and confirmed the results with experiments in mice.

Also, large-scale molecular biology studies like genomic, transcriptomic, proteomic and transposon insertion studies make good use of Galleria. They allow researchers to paint a more complete picture of molecular responses during infection, for example, to discover virulence factors in bacterial pathogens on a larger scale.

In large-scale molecular biology studies, one can use Galleria to validate mutants of microbial pathogens.

Lastly, Galleria is ideally suited for the initial mass screening of the safety and effectiveness of novel medicinal and chemical compounds. Different studies have successfully used Galleria to assess the toxicity and efficacy of a number of novel antibiotics and antifungal compounds.

 

Where is the future of Galleria headed?

We predict Galleria will become commonplace in scientific studies, as more research centres pop up. For example, Australia’s very first Galleria Research Facility was established at Macquarie University in 2020 and has already successfully employed Galleria to test the toxicity and efficacy of novel drugs, as well as study how various microorganisms cause disease.

Like moths attracted to flames, we expect that more and more scientists will embrace Galleria mellonella as their preferred animal models.

 

About the authors of this blog

Hue Dinh is a Postdoctoral Research Fellow in the Cain Laboratory and manager of Galleria Research Facillity at Macquarie University. Her work focuses on antibiotic resistance and the use of Galleria models for different applications.

Hannah Lott is a Master of Research Candidate in the Cain Laboratory at Macquarie University. Her research focuses on characterising the nature of bacterial interactions using functional genomics.

Amy Cain is an ARC DECRA fellow at School of Natural Sciences, Macquarie University where she is Head of the lab of Functional Genomics and Antibiotic Development. She is also a Founder and Director of the Galleria Research Facillity and Director of Joint Academic Microbiology Seminars (JAMS). Her work focused on developing new antibiotics using functional genomics and the Galleria in vivo model.

 

About this blog section

The section #MicrobiologyEvents for the #FEMSmicroBlog reports about events and meetings relevant to our network. These include world awareness days, FEMS-sponsored meetings or meetings of Member Societies and many more.

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