ANTI-VeC

Title: Characterization of Microsporidia MB and Wolbachia endosymbionts in Anopheles gambiae and Anopheles funestus in Lwiro, a high-altitude region in Eastern DR Congo

Principal Investigator: Janvier Balikubiri Bandibabone (Centre de Recherche en Sciences Naturelles (CRSN/Lwiro))

Co Investigator 1: Thomas Walker (The London School of Hygiene & Tropical Medicine)

Co Investigator 2: Mojca Kristan (The London School of Hygiene & Tropical Medicine)

Co Investigator 3: Seth Irish (Centers for Disease Control and Prevention)

Project Summary: It has been shown that both Microsporidia MB and Wolbachia strains have the ability to block the development of Plasmodium falciparum in Anopheles mosquitoes. Recently a collaborative project was undertaken looking at Wolbachia strains in Anopheles species and we were able to show that high density strains are present in An. moucheti and An. demeilloni from Lwiro, DRC. To date, no data has been generated on the prevalence of Wolbachia and Microsporidia MB in An. gambiae s.l. and An. funestus populations of Lwiro. These two species are the main malaria vectors in the region and the project aims to determine the prevalence and density of Microsporidia MB and Wolbachia in Lwiro and surrounding populations in Eastern DR Congo. Mosquitoes will be collected on a vertical transect at altitudes between 1400-1800 m. Adults will be collected in houses using CDC light traps and larvae will be collected from breeding sites located in the region. Colonization of An. gambiae and An. funestus will be first undertaken in the Medical Entomology and Parasitology Laboratory of the Centre de Recherche en Sciences Naturelles (CRSN/Lwiro). The resulting wild caught F0 and early generation adults of An. gambiae and An. funestus will be sent (or delivered in person as part of capacity training) to the London School of Tropical Medicine and Hygiene (LSHTM) for qPCR screening to identify and quantify Microsporidia MB, Wolbachia and Plasmodium. The abundance of An. gambiae and An. funestus species and the presence of Wolbachia in other Anopheles makes the Lwiro region an ideal place for this entomological study of endosymbionts present in the two major Anopheles malaria vectors. Our results will provide important data on the prevalence and density of these two endosymbionts that are showing great promise as biocontrol candidates for malaria vector control.

Countries involved:

• Democratic Republic of the Congo (DR Congo)
• UK
• USA

Title: Prevalence, seasonality and associated microbiota of Microsporidia MB in malaria vectors from Central Mozambique and Coastal Kenya

Principal Investigator: Marta Maia (KEMRI Wellcome Trust Research Programme)

Co Investigator 1: Caroline Kiuru (Barcelona Institute for Global Health (IS Global) / Centro de Investigacao em Saude de Manhica)

Co Investigator 2: Martin Rono (KEMRI Wellcome Trust Research Programme)

Co Investigator 3: Joseph Mwangani (KEMRI Wellcome Trust Research Programme) 

Project Summary: Given the profound effect of Microsporidia MB in inhibiting Plasmodium transmission and its potential as a transmission blocking tool there is a need to evaluate the prevalence of microsporidia in nature and how the Microsporidia MB interacts with other microbes. The proposed study aims at investigating the prevalence and seasonality of Microsporidia MB in central Mozambique and Coastal Kenya. In addition, the study will assess the presence of Microsporidia MB and its relationship with associated microbiota found in the midgut and ovaries of mosquitoes of the main malaria vector complexes, A gambiae and A funestus.

Countries involved:

• Kenya
• Mozambique

Title: Microsporidia species distribution and its interaction with insecticide resistance in Anopheles gambiae complex and Anopheles funestus group in Nigeria

Principal Investigator: Uwemedimo Ekpo (Federal University of Agriculture, Abeokuta)

Co Investigator 1: Monsuru Adeleke (Osun State University, Osogbo)

Co Investigator 2: Adedoyin Osipitan (Federal University of Agriculture, Abeokuta)

Co Investigator 3: Idowu Oluwafunmilayo (Federal University of Agriculture, Abeokuta)

Co Investigator 4: Olufunke Shittu (Federal University of Agriculture, Abeokuta)

Project Summary: Microsporidia harboured by mosquitoes are known to influence the fitness of the mosquito to transmit malaria parasite and to reproduce. However, exposure to insecticides and the development of insecticide resistance in mosquitoes have been shown to alter mosquito biology in ways that interfere with their susceptibility to invasion by various microorganisms. Therefore, it is important to understand the interactions between insecticide resistance and the prevalence and diversity of Microsporidia found in Anopheles mosquito populations responsible for the transmission of malaria. This study will map the distribution of Microsporidia in Anopheles populations in Nigeria. The importance of insecticide resistance status as a biological consideration for the use of Microsporidia as innovative tools for the elimination of malaria in endemic areas will also be evaluated.

Countries involved:

Nigeria

Title: Bionomics and molecular characterization of Microsporidia MB in Anopheles gambiae s.l. and Anopheles funestus in selected site in Kenya

Principal Investigator: Luna Kamau (Kenya Medical Research Institute)

Co Investigator 1: Damaris Matoke-Muhia (Kenya Medical Research Institute)

Co Investigator 2: Eric Ochomo (Kenya Medical Research Institute)

Co Investigator 3: Joseph Mwangangi (Kenya Medical Research Institute)

Project Summary: Microsporidia are naturally occurring obligate intracellular eukaryotes that infect a variety of insect species including mosquitoes. Their potential for use as biological control agents has long been attributed to their effects on mosquito life-table parameters such as larval survivorship, fecundity and life span. Microsporidia have also been found to affects phenotypic expression of resistance in Anopheles gambiae as well as malaria parasite transmission under laboratory conditions. Although the mechanisms of the effects of microsporidia are not fully elucidated, activation of the insects’ immune system and high metabolic demands resulting from infection are thought to be possibilities. Various microsporidia strains have been described and studied. Microsporidia MB is a non-pathogenic native and novel microsporidia species isolated from Anopheles mosquitoes collected from Mbita and Mwea regions of Kenya and was found to impair malaria parasite transmission both in the field and laboratory. The goal of the proposed study is to improve understanding on the Microsporidia MB distribution, genetic diversity and association with factors that are relevant for vector control so as to aid in their effective deployment for malaria vector control. We will investigate the prevalence and genetic diversity of Microsporidia MB in wild populations of An. gambiae s.l. and An. funestus, determine their potential role in modulation of susceptibility to insecticides and association with selected molecular markers of resistance and explore environmental predictors of Microsporidia MB infection in nature. We will also determine the fitness cost associated with Microsporidia MB infection.

Countries involved:

Kenya

Title: Diversity of Microsporidia MB, their co-occurrence and dynamics with bacterial communities associated with Anopheles mosquitoes

Principal Investigator: Jewelna Akorli (Noguchi Memorial Institute for Medical Research)

Co Investigator: Samuel Dadzie (Noguchi Memorial Institute for Medical Research)

Project Summary: The concept of mosquito holobiont has recently been acknowledged as necessaryto give clearer understanding of the role of micro-organisms in vector competence. While bacteria have been extensively studied, there is growing evidence that fungi and insect-specific viruses could also play significant roles in the vector biology of mosquitoes. Mosquito-associated bacteria and their roles in vector biology and ecology are being elucidated among Anopheles mosquitoes in Ghana. In light of recent findings of Microsporidia MB in An. arabiensis and their effects on Plasmodium transmission, we propose to study the prevalence and diversity of the microsporidia in Anopheles mosquitoes in Ghana and, investigate their cooccurrence and changing intensity dynamics with gut microbiota during themosquito adult life. The survey will involve collection of late-stage larvae and pupae from breeding sites and adult mosquitoes in and around homes in selected sites in Ghana. In addition, we will study abiotic factors that may influence the incidence of the fungus in breeding sites and the potential for horizontal transmission of the microsporidia through the larval habitat by conducting water physicochemical assessments and screening the water for MB, respectively. Midguts and reproductive tissues will be dissected for bacteria and microsporidia analyses in emergents using Illumina 16S amplicon sequencing and PCR/qPCR. Field-caught gravid females will be allowed to lay eggs separately for identification and pooling of MB-positive and -negative for study of the co-dynamics of bacteria and Microsporidia MB in the female mosquito adult life. Finally, excreta from infected female adults will be tested for the presence of Microsporidia MB as a possible method for identifying infected adult mosquitoes. Results from this study will expand knowledge of the ecology and inter-relationship of mosquito holobiont to ultimately inform their potential use as novel control tools.

Countries involved:

Ghana

Title: Genetic diversity and maternal transmission of Microsporidia MB strains in field populations of the major malaria vector Anopheles gambiae s.l. in Cameroon.

Principal Investigator: Maurice Marcel Sandeu (Centre for Research in Infectious Diseases)

Co Investigator: Charles Wondji (Centre for Research in Infectious Diseases / Liverpool School of Tropical Medicine)

Project Summary: Malaria remains a major public health burden in Africa.  Increasing insecticide resistance in mosquitoes demands the development of new approaches to fight this disease.  Paratransgenesis and RNAi approach by using engineered microorganisms have been shown to reduce mosquito vector competence. More recently, research efforts have suggested that Microsporidian MB symbionts of mosquitoes offer a possible way of controlling malaria, as they impede the development of Plasmodium parasites within the Anopheles arabiensis mosquito. However, the presence of Microsporidian MB symbiont has not been widely investigated in other Anopheles species and/or in other African regions such as Central Africa.

The proposed research aims to evaluate the prevalence of Microsporidian MB symbiont infections among wild An. gambiae s.s and An. coluzzii (larvae and adult mosquitoes) populations from two eco-geographical regions of Cameroon and assess their phylogenetic relationship to other arthropod strains.

In addition, we will examine the interactions between Microsporidian MB symbionts and natural Plasmodium development, then and other bacteria symbionts such as Asaia in field mosquitoes; Also, we will assess the vertical transmission of Microsporidian MB in Anopheles mosquitoes.

Through this project, we will develop a wider understanding of the prevalence and diversity of Microsporidian MB in Anopheles gambiae s.l., their interactions with Plasmodium infection with other bacteria symbionts, and their potential role of transmission to the progeny in An.gambiae s.l. This project will contribute to the potential introduction of natural symbionts into Anopheles mosquito populations from endemic areas facilitating this promising strategy to prevent and reduce malaria transmission.

Countries involved:

Cameroon

Title: Investigating Microsporidia MB diversity and prevalence in An. Gambiae sl. and An. Funestus sl. Populations in wet agricultural area (rice field) in Benin

Principal Investigator: Genevieve Mahounon Tchigossou (International Institute of Tropical Agriculture)

Project Summary: Insecticide resistance poses a growing challenge to malaria vector control in Benin and around the world. The currently used tools such as LLINs and IRS are affected by resistance of mosquitoes and constitute a threat for malaria elimination. Additional tools that will enable to simultaneously exert pressure on the malaria transmission from different angles are needed. Recent studies have shown that mosquito symbionts play important roles in malaria parasite development, survival and sporozoite prevalence, thus modulating vector competence. In addition, these microbes colonized mosquitoes during the aquatic life stage from aquatic habitats. Herren et al., discovered that a vertically transmitted microsporidian symbiont (Microsporidia MB) in the An. Gambiae complex can impair Plasmodium transmission but this mosquito symbiont (Microsporidia MB) has not been explored in relation to its habitats. To address this research gap, this project will screen the presence and the diversity of Microsporidia MB with its prevalence in An. Gambiae and A. Funestus in rice fields in Benin. Specifically, (i) An. Gambiae sl. and A. Funestus sl. and their breeding sites (water samples) will be collected in dry/rainy season in different (3) rice fields in Benin; (ii) Microsporidia MB and Plasmodium falciparum in An. Gambiae sl and A. Funestus sl. populations collected in the different rice fields will be screened and the composition of breeding sites analysed; (iii) Microsporidia MB diversity will be determined. The data gathered on Microsporidia MB diversity in malaria vectors from different larvae niches and its capacity to protect mosquitoes from Plasmodium infection can be used to complement existing insecticide resistance surveillance tools.

Countries involved:

Benin

Title: Spatio-temporal dynamics of Burkina Faso (West Africa) local strain(s) of Microsporidia MB and their prevalence with malaria parasites and insecticide-resistance

Principal Investigator: Abdoulaye Diabate (Institute de Recherche en Sciences de la Sante - Center Muraz)

Co Investigator: Simon Sawadogo (Institute de Recherche en Sciences de la Sante - Center Muraz)

Project Summary: Traditional malaria control strategies using long-lasting insecticide-treated bednets and indoor residual spraying have reduced the malaria burden by nearly 50% in many endemic areas in 2015. However, due to the emergence and rapid spread of insecticide and drug resistance, malaria reduction has stalled, and any hope of eradication requires the introduction of novel control tools. The endosymbiont microorganisms of arthropods including mosquitoes are presented as a potential candidate that can effectively control malaria vectors. Recently non-virulent and vertically transmitted, Microsporidia was isolated in Kenya in East Africa on Anopheles arabienis mosquito (Herren et al., 2020). A strong negative correlation occurred between the presence of Microsporidia MB and the malaria parasite. However supplementary investigation is needed to withdraw more conclusions regarding the prevalence and the impact of Microsporidia MB on plasmodium transmission blocking but also on insecticide resistance in field population of mosquitoes.

In Burkina Faso at IRSS, Through an ANTI-VeC Training and collaborative Award, we generated important results that are important contribution to Herren et al., recent studies. We found a natural prevalence of ~ 4.17 % of MB in wild Anopheles mosquitoes over 546 sample analyzed in two villages of Burkina Faso during the dry season (unpublished data).Then, two MB (Anopheles gambiae and Anopheles coluzzii) infected colonies are currently being established in our lab. The question is, is there a relationship between field mosquitoes insecticide resistance status, malaria parasite plasmodium prevalence and Microsporidia MB prevalence?

In this proposal, we focus, over a one-year timeframe, on screening different populations of Anopheles mosquito for Microsporidia MB infection. We will also examine the correlation between the prevalence of MB infection and plasmodium infection and also with insecticide resistance in order to provide useful data regarding the practical utility of Microsporidia MB for malaria control in West Africa.

Countries involved:

Burkina Faso

Title: Establishment of stable MB-carrying Anopheles lines and population studies in large cages

Principal Investigator: Maria Vittoria Mancini (Polo D'Innovazione Genetica, Genomica e Biologia)

Project Summary: The aim of the proposed project is to establish, stabilize and characterized populations of Microsporidia MB-carrying Anopheles collected in several geographic areas of African countries. Basic life history parameters and traits of the symbiotic interactions between MB and hosts from different genetic backgrounds will be explored and compared.

Due to the contribution of males in MB transmission during mating, behavioural studies on the mating choice of MB-carrying males towards females will also be assessed to provide insights in their reproductive capacity.

Transmission rates and spreading dynamics of Microsporidia MB in mosquito populations will be explored in large cages environments, mimicking natural field conditions and population dynamics, with the aim of supporting predictive scenarios for the development of potential MB-based vector control interventions.

Countries involved:

Italy