Despite the great success of last decades¿ control of malaria, still >200 million cases and >400.000 deaths occurred in 2018, 90% of which in Africa. The most effective strategy towards malaria elimination today is represented by massive campaigns of distribution of Insecticide Treated Nets (ITNs), whose effectiveness is threatened by increasing physiological and behavioural resistance of vector populations. Understanding vector species boundaries and behavioural features, reproduction isolation, population structure and gene flow is crucial for both maximising the lifespan of available insecticides and for guiding the implementation and predicting effectiveness of novel genetic-based vector control tools envisaged to complement ITNs in the fight against malaria in Africa in the future.
The present project is based on the long-standing and internationally recognised expertise of the MedEnt group on the study of the speciation process ongoing within the two most efficient Afrotropical malaria vectors, Anopheles coluzzii and A. gambiae. In recently funded projects, we developed two novel, easy-to-implement tools for genotyping Ancestry Informative Markers in the two species, taking advantage of results from the Anopheles gambiae 1000 Genome project. We here propose to exploit these novel approaches to deepening current understanding of the eco-geographic determinants of A. coluzzii, A. gambiae and hybrid genotype distribution across Africa, and to characterize their behavioral traits, with particular reference to those more significant for malaria transmission and control. The funding of the project represents an instrumental opportunity for MedEnt research group to build on previous results, to continue contributing high quality results to the research field, as well as maintaining a direct link within a vibrant and highly competitive community of international scientists focused on providing new data and means for improved malaria control in Africa.
The present project is based on the long-standing and internationally recognised expertise of the MedEnt group in the Department of Public Health & Infectious Diseases in Sapienza University on the study of the speciation process ongoing within the A. gambiae complex and on its consequences for malaria epidemiology and control in Sub-Saharan Africa. THE FUNDING OF THE PRESENT PROPOSAL REPRESENTS AN INSTRUMENTAL OPPORTUNITY FOR MedEnt TO BUILD ON RECENT (AND LESS RECENT) RESULTS, TO CONTINUE CONTRIBUTING HIGH QUALITY RESULTS TO THE RESEARCH FIELD, AS WELL AS MAINTAINING A DIRECT LINK WITHIN A VIBRANT AND HIGHLY COMPETITIVE COMMUNITY OF INTERNATIONAL SCIENTISTS FOCUSED ON PROVIDING NEW DATA AND MEANS FOR IMPROVED MALARIA CONTROL IN AFRICA. IT WILL ALSO ALLOW REINFORCING COLLABORATION WITH MALARIA ENTOMOLOGY RESEARCH GROUPS IN AFRICA.
The genotyping assays we propose to be widely exploited stem from recent result of expiring projects funded by Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Sapienza University (ATENEO 2018). The present project will allow prompt application of these assays in regions from where little is known on the degree of admixture between A. coluzzii and A. gambiae and contribute to increase the assay¿s exploitation by other groups by providing new evidence of the biological relevance of the complex relationships within/between the two species and of their impact on malaria epidemiology. More in detail, we expect the inherent innovative nature of the project will contribute to advance knowledge in different field, as follows.
MALARIA ENTOMOLOGY IN SUB-SAHARAN AFRICA. The novel bi- and multi-locus PCR assays developed by MedEnt are specifically designed in order to be easily implementable and affordable to malaria entomology research groups operating in endemic regions. Ambitiously (but realistically, given the success of the diagnostic methods developed for A. coluzzii and A. gambiae by the group almost 20 years ago and today routinely applied in entomological surveys in Africa and quoted by hundreds scientific publications), we expect that the association of conventional X-linked diagnostic markers for A. coluzzii and A. gambiae with the novel bi-locus (and multi-locus, when needed) PCR assays will eventually become widely applied by the malaria entomology community in Africa. We expect that the exploitations of these tools in the present project - which inherently implies reinforcing existing collaborations between our group African research groups (and hopefully creating new ones) - will contribute to make these new tools rapidly and widely applied and their advantages compared to conventional diagnostic methods renown. We envisage that in addition to the specific expected contribution of the proposed studies to the research field, the project will have a great contribution in improving the research capacity of malaria entomologist in Africa and allow to rapidly gaining information from the several Afrotropical areas from where no data on genetic divergence and reproductive isolation between these two major malaria vector species are presently available. The recent findings of new populations with admixed/hybrid genotypes in far West (such those from the coast of Ivory Coast, unpublished data) as well as in far East (Kenya, AG1000g project) Africa reveal that despite decades of studies the knowledge on the genetics and ecology of these two vector species is still fragmentary and referred to relatively few areas across the African continent and we aim to contribute to fil the gaps.
MALARIA EPIDEMIOLOGY AND CONTROL. The time is today mature to transfer the extensive knowledge on the high existing genomic heterogeneity in A. coluzzii and A. gambiae in the field of malaria epidemiology and for realistic predictions of effectiveness of conventional (ITNs) and innovative (e.g. CRISPR-Cas9-based gene-drive) approaches to reduce malaria transmission in Africa. We believe that the application of the novel PCR-assays will promote this process by allowing to better assess in the whole afro tropical region (and not only in selected regions where most studies are presently carried out) gene-flow between A. coluzzii and A. gambiae and predict the possible impact of genetic heterogeneities, adaptation capacity and hybridization process on the effectiveness and sustainability of genetic control strategies. In addition, we expect that the project results will allow to clarify the behavioural traits and epidemiological relevance of the novel ¿hybrid form¿ in HHZ and beyond.
EVOLUTION BIOLOGY. We expect our results will provide novel details on the speciation process ongoing in two vector species (which are considered model organisms in the field ecological speciation) as a result of human activities and human-made environmental modifications, from the perspective of providing a window into what may represent contemporary adaptive introgression on a trajectory towards hybrid speciation.