A groundbreaking initiative co-led by Strathclyde could transform the fight against vector-borne diseases by studying bacteria linked to mosquitoes.

According to figures from the World Health Organisation, vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually. Malaria causes an estimated 249 million cases globally, and results in more than 608,000 deaths every year, with most of the deaths occurring in children under five.

Dengue fever

Pathogens transmitted by the blood feeding insects are a major global health issue and cause not only malaria but also major viral diseases such as dengue fever or serious birth defects caused by the Zika virus.

The effects of climate change could increase the chance of mosquito and tick-borne viruses appearing in the UK as multiple encephalitis cases have already been identified here. The UK Health Security Agency has set up a new early warning system to help detect outbreaks as climate change expands the geographical range of habitats suitable for mosquitoes.

Now researchers from the UK and USA have joined forces to create the MosAIC (Mosquito-Associated Isolate Collection) initiative, the first large-scale repository of mosquito-associated microbiomes including genome data and isolates, which could reveal how different bacteria in the microbiome affect their mosquito host, including its ability to spread pathogenic viruses.

Culture collection

Researchers from across the mosquito research community contributed bacterial isolates directly from mosquitoes or the environment they inhabit, which were then both whole-genome sequenced, providing openly accessible data, and creating a culture collection.

Although there are more than 3,700 different types of mosquitoes worldwide, there is still a poor understanding of the complexity of the insect’s microbiomes. These impact how well they can transmit viruses and can also make them more susceptible to passing on viruses. The composition of the mosquito microbiome is dynamic and affected by host species, geography and varies across individuals and their life stage.

Promising alternative

With increasing resistance of mosquitoes against insecticides, microbiome manipulation is a promising alternative avenue for future disease control measures, and scientists hope that by cataloguing their bacterial diversity, it will lead to a better understanding of transmission of diseases.

A paper outlining the project has been published in the PLOS Biology journal, and Dr Eva Heinz, from the Strathclyde Institute of Pharmacy and Biomedical Sciences at the University of Strathclyde, said:

“We don’t have enough understanding yet of mosquito microbiomes. With the increase of insecticide resistance and the need for new approaches, this collection could help us create a new tool for vector controls.

“It offers a unique, highly valuable resource for research on bacterial colonisation and adaptation within mosquito hosts. Already we have increased the number of mosquito-associated bacterial genomes by more than ten times, from 35 to 392.

“It’s a huge step to understanding what is there and can be accessed by researchers. Improvements in malaria control are stalling, and insecticide, as well as antimalarial resistance spread, means we are losing control tools. “

This project was also co-led by researchers from the University of Wisconsin-Madison in the USA and Liverpool School of Tropical Medicine and the University of Salford in the UK and includes contributions from 10 labs across the mosquito research community.

Global challenge

Laura Brettell, University Fellow at the University of Salford, said: “In the future, the insights gained from this work could lead to the development of much needed novel ways to harness naturally occurring bacteria to combat mosquito-borne diseases – tackling a critical global health challenge.”

The project is funded by the U.S. National Science Foundation and the UKRI Biotechnology and Biological Sciences Research Council (BBSRC).