ANTI-VeC awarded 10 pump-priming projects up to £100,000 at the end of 2018, which are due to conclude in 2020. One of these projects, led by Dr Jeremy Herren (ICIPE, Kenya) with co-investigators, Prof Steve Sinkins (Glasgow) and Mara Lawniczak (Wellcome Sanger Institute) explores anopheles-microsporidia MB symbiosis and how it can be used in mosquitoes to decrease malaria transmission. In the third of our profiles of awarded projects, we caught up with Dr Jeremy Herren to find out how the project is progressing.

Briefly describe the project for us?

“Prior to the ANTI-VeC pump-priming grant, we discovered a novel microsporidian symbiont of Anopheles arabiensis mosquitoes that blocks the transmission of Plasmodium, called Microsporidia MB. This project is aimed at investigating the transmission routes used by this symbiont and determining if it could be developed into a malaria control strategy.”

What are the unknowns/gaps in knowledge that you are investigating?

“Very little is known about the biology of this symbiont. We are especially interested in determining how it is transmitted from one mosquito to another, since we believe that if we could strategically increase the rate of transmission (by releasing infected mosquitoes or microsporidian spores), we could increase the prevalence of Microsporidia MB in Anopheles arabiensis, and hence decrease their capacity to transmit malaria.”

When did the project begin and what have you explored so far?

“The project started in February 2019 and since then we have been investigating the symbiont's vertical transmission route, establishing that mothers transmit their infections with a high level of efficiency to their offspring. We have been able to visualise this process in the mosquito ovary using confocal microscopy. At the Wellcome Sanger Institute, we carried out RNA-seq on Microsporidia MB infected ovaries to investigate how the symbiont may be interacting with its host environment. Currently, we are investigating the horizontal transmission routes, in particular a sexual transmission route whereby infected males could be transmitting the infection to females upon mating.”

How are you and your partners working together to realise this project?

“In September 2019, Silvain Pinaud, a post doc in the group of Mara Lawniczak (partner) visited the primary site of the project research (Mbita, on the shores of Lake Victoria, Kenya). Over the course of the visit a number of experiments were conducted with the aim of preparing samples from various organs of Microsporidia MB infected mosquitoes for RNA and DNA sequencing. Steve Sinkins (partner) has also been involved in many aspects of the project in an advisory capacity and will be visiting project sites in Kenya in 2020.”

Is there an example of evidence/data that has surprised you from your experiments so far?

“We’ve been very impressed with the rate of vertical transmission from mother to offspring. This feature of Microsporidia MB has allowed us to establish infected and uninfected lines for experiments. In a recent experiment, we observed that an infected male transmitted the Microsporidia MB infection to an uninfected female. We are currently investigating if sexual transmission is a major route of infection. We are excited by this result, as it could be used to disseminate the symbiont through Anopheles mosquito populations much more effectively.”

What are you hoping the completed project will tell us? 

“We hope this project give us important insights into transmission routes of Microsporidia MB and contribute to the prospect of using symbionts for controlling malaria transmission.”

First published: 5 May 2020

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