Understanding the evolution of immune genes in jawed vertebrates

Driven by co-evolution with pathogens, host immunity continuously adapts to optimize defence against pathogens within a given environment. Recent advances in genetics, genomics and transcriptomics have enabled a more detailed investigation into how immunogenetic variation shapes the diversity of immune responses seen across domestic and wild animal species. However, a deeper understanding of the diverse molecular mechanisms that shape immunity within and among species is still needed to gain insight into-and generate evolutionary hypotheses on-the ultimate drivers of immunological differences. Here, we discuss current advances in our understanding of molecular evolution underpinning jawed vertebrate immunity. First, we introduce the immunome concept, a framework for characterizing genes involved in immune defence from a comparative perspective, then we outline how immune genes of interest can be identified. Second, we focus on how different selection modes are observed acting across groups of immune genes and propose hypotheses to explain these differences. We then provide an overview of the approaches used so far to study the evolutionary heterogeneity of immune genes on macro and microevolutionary scales. Finally, we discuss some of the current evidence as to how specific pathogens affect the evolution of different groups of immune genes. This review results from the collective discussion on the current key challenges in evolutionary immunology conducted at the ESEB 2021 Online Satellite Symposium: Molecular evolution of the vertebrate immune system, from the lab to natural populations

Discrepant Prevalence and Incidence of Leishmania Infection between Two Neighboring Villages in Central Mali Based on Leishmanin Skin Test Surveys

Leishmaniasis is a vector-borne disease transmitted to humans by the bite of an infected sand fly. Leishmaniasis is present in more than 88 countries and affects more than 12 million people. Depending on the species of Leishmania, the host can develop cutaneous leishmaniasis (CL), which is characterized by skin ulcers in uncovered parts of the body or a more severe form, visceral leishmaniasis, which affects the liver and spleen and is fatal if not treated. This study aims to establish the past and present infection with Leishmania parasites in two villages where recent cases have been diagnosed by the dermatology center (CNAM) in Bamako. This was achieved using a Leishmania-specific skin test that was administered annually to permanent residents of Kemena and Sougoula villages from 2006 to 2008. The results show that transmission of Leishmania is active and stable in these two villages. Moreover, despite sharing similar cultural and environmental features, the individuals from Kemena presented three times the risk of Leishmania infection compared with those from Sougoula. Our findings raise awareness of the continued presence of CL in Mali

Windborne long-distance migration of malaria mosquitoes in the Sahel

Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3–8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40–290 m above ground level and provide—to our knowledge—the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled

Mosquito control by abatement programmes in the United States: perspectives and lessons for countries in sub-Saharan Africa.

Africa and the United States are both large, heterogeneous geographies with a diverse range of ecologies, climates and mosquito species diversity which contribute to disease transmission and nuisance biting. In the United States, mosquito control is nationally, and regionally coordinated and in so much as the Centers for Disease Control (CDC) provides guidance, the Environmental Protection Agency (EPA) provides pesticide registration, and the states provide legal authority and oversight, the implementation is usually decentralized to the state, county, or city level. Mosquito control operations are organized, in most instances, into fully independent mosquito abatement districts, public works departments, local health departments. In some cases, municipalities engage independent private contractors to undertake mosquito control within their jurisdictions. In sub-Saharan Africa (SSA), where most vector-borne disease endemic countries lie, mosquito control is organized centrally at the national level. In this model, the disease control programmes (national malaria control programmes or national malaria elimination programmes (NMCP/NMEP)) are embedded within the central governments' ministries of health (MoHs) and drive vector control policy development and implementation. Because of the high disease burden and limited resources, the primary endpoint of mosquito control in these settings is reduction of mosquito borne diseases, primarily, malaria. In the United States, however, the endpoint is mosquito control, therefore, significant (or even greater) emphasis is laid on nuisance mosquitoes as much as disease vectors. The authors detail experiences and learnings gathered by the delegation of African vector control professionals that participated in a formal exchange programme initiated by the Pan-African Mosquito Control Association (PAMCA), the University of Notre Dame, and members of the American Mosquito Control Association (AMCA), in the United States between the year 2021 and 2022. The authors highlight the key components of mosquito control operations in the United States and compare them to mosquito control programmes in SSA countries endemic for vector-borne diseases, deriving important lessons that could be useful for vector control in SSA

Utilisation of wastewater for fuel and fodder production and environmental and social benefits in semi-arid, peri-urban zones of sub-Saharan Africa. Final Report 1/12/2002 - 30/11/2007 Contract number ICA4-CT-2002-10017

The overall objective was to develop low-tech water treatment and irrigation systems and test their use for the production of fuel wood and fodder in semi-arid sub-Saharan Africa. Sites for waste water treatment plants and irrigation systems were identified and the systems were constructed in Burkina Faso, Mali and Niger. Project partners were trained in how to use and maintain the systems. The irrigation sites were characterised in advance of tree planting, and soil and water analyses are being conducted regularly. Tree species with potential for use in irrigated conditions in each country were identified and experimental designs for the trials produced. Some species were used in common in all three countries. Nursery screening trials were conducted and plants were then planted at the irrigation sites. Trees grew quickly under the irrigated conditions and many species performed well. Species which were selected for their good performance in the nursery were not necessarily the best performers in the field. Biomass production was determined and the effects of different coppicing treatments on regrowth were assessed. Parameters of planting stock quality were assessed and incidence of pest attacks determined. Partners were also trained in the use of sap flow and associated equipment. Considerable variation between tree species in water use was noted, together with differential effects according to the inoculation history of the plants. Working in controlled glasshouse conditions, using sterilised soil media, considerable variation in effectiveness of different mycorrhizal strains on different tree species was detected. When plant response to simulated irrigation water was measured, uninoculated plants grew very poorly irrespective of whether they are receiving the simulated irrigation water or not. Thus mycorrhizal infection enabled plants to make use of the nutrients in the irrigation water. Initially, nursery and field studies gave much less clear results. However, assessments during the final year of the project demonstrated positive effects of inoculation on tree growth in Mali and Niger. These observations were reinforced on the rhizobial side by molecular studies, using strain-specific probes for nodule analysis. In Ouagadougou it was estimated that 225,004 tons of fuel wood and 6708 tons of charcoal per year are transported to the city. The average price of firewood was approximately 21 F CFA per kg, and charcoal was 60 – 110 F CFA per kg. Sellers can achieve a substantial income from sales. The large quantities of fuel imported into Ouagadougou highlight the pressure on fuel resources. This is further indicated by the observations in Niger and Mali. Dissemination to stakeholders has been conducted and is continuing. The irrigation sites are continuing to be run. An important development is the formation of a partnership with representative farmers’ organizations regrouped under the umbrella of ROPPA (Réseau des Organisations Paysannes et des Producteurs Agricoles d’Afrique de l’Ouest, who federates millions of farmers through twelve west African countries, with the objective of bringing symbionts to farmers

Prevalence des trypanosomoses bovines dans les cercles de kadiolo et sikasso au mali avant le demarrage de la champagne de lutte.

L’objectif du projet TCP/MLI/3402 FAO est d’initier une campagne de protection efficace et durable des bovins contre la Trypanosomose Animale Africaine (TAA) et la résistance aux trypanocides par le contrôle de la mouche tsé-tsé combiné aux traitements stratégiques des animaux. Préalablement à la mise en oeuvre des activités de lutte, une étude de base protozoologique a été confiée au Laboratoire Central Vétérinaire (LCV). 35 villages ont été enquêtés dans les cercles de Kadiolo (20 villages dans 9 communes) et Sikasso (15 villages dans 4 communes). Pour l’étude protozoologique 1208 prélèvements sanguins ont été effectués chez des bovins, 15 trypanosomes ont été identifiés dont 9 à Kadiolo et 6 à Sikasso. Tous les trypanosomes observés sont de l’espèce Trypanosoma vivax. La prévalence de la trypanosomose est de 1.12% dans le cercle de Kadiolo et 1.2% dans le cercle de Sikasso. Pour l’ensemble de la zone d’étude, la prévalence est de 1.16%. La moyenne du taux d’hématocrite est de 28.9 dans le cercle de Kadiolo et 33.4 dans le cercle de Sikasso. La moyenne du taux d’hématocrite pour l’ensemble de la zone est de 31.15Mots clés : Prévalence, Trypanosomoses, Bovines, Lutte, Mali

Utilisation of wastewater for fuel and fodder production and environmental and social benefits in semi-arid, peri-urban zones of sub-Saharan Africa. Fifth Annual Report: 1/12/2006 – 30/11/2007

Summary Report Since the beginning of the contract, the results achieved are as follows: Work package 1 Water treatment and irrigation Sites for waste water treatment plants and irrigation systems were identified and the systems have been constructed in Burkina Faso, Mali and Niger. Progress was slower than planned for a variety of reasons, including delays to obtaining permits for construction, delays associated with importation and shipping of components and delays in purchase of expensive items due to cash flow problems. Staff have been trained in how to use and maintain the systems. Some modifications and refinements and repairs have been necessary, but systems are functioning in each country. The irrigation sites were characterised in advance of tree planting, and soil and water analyses are being conducted regularly. Work package 2 Tree growth and management Tree species with potential for use in irrigated conditions in each country were identified and experimental designs for these trials were produced. Some species are being used in common in all three countries. Nursery screening trials were conducted and plants were then out planted to the irrigation sites. Trees have grown quickly under the irrigated conditions and many species are performing well. Few problems have been detected. Species which were selected for their performance in the nursery are not necessarily the best performers in the field plots. In this year, biomass production has been determined and the effects of coppicing at 2 different heights on regrowth have been assessed. Work package 3 Tree water use and soil water status Staff in all three countries with irrigation systems have received training in the use of sap flow, soil water and associated measuring equipment. In Mali, considerable variation between tree species in soil water use has been noted, together with differential effects according to the inoculation history of the plants. Acacia angustissima appears to have particularly high water use and is easily water-stressed, whereas A. mangium appears to be more robust in its performance. Even with irrigation, tree water use is declining by the late morning, indicating stomatal closure. In Burkina Faso, L. hybrid showed the highest transpiration rate (1.09 L cm-2 day-1), followed by L. leucocephala (0.93 L cm-2 day-1), G. sepium (0.93 L cm-2 day-1) and A. angustissima (0.61 L cm-2 day-1). Gliricidia did not show morning stomatal closure, whereas Acacia and the Leucaenas did. Stomatal closure was especially marked with Acacia angustissima, confirming the results previously obtained in Mali. The long term use of physiological equipment under tropical conditions has proved difficult as the equipment is not particularly robust. Work package 4 Microsymbionts and N fixation Working in controlled glasshouse conditions, using sterilised soil media, the UK partner has identified considerable variation in effectiveness of different mycorrhizal strains on different tree species. After the initial screening phase, selected tree species were taken on to the second phase of the study in which plant response to simulated irrigation water is being measured. Uninoculated plants grew very poorly irrespective of whether they are receiving the simulated irrigation water or not. The response of inoculated plants to irrigation varied with inoculant and tree species. Initially, nursery and field studies in Mali, Niger and Burkina Faso gave much less clear results. However, assessments during this final year of the project have demonstrated positive effects of inoculation on tree growth in Mali and Niger. These observations are reinforced by molecular studies, using strain-specific probes for nodule analysis, which have been successfully tested against the inoculants, studies on samples collected from the field experiments in Mali suggest that the inoculant strains are absent – other types are present. This suggests that either the original inoculation was unsuccessful, or that the inoculants have been out-competed by indigenous strains. Work package 5 Economics and quality of produce Questionnaires have been developed by the partner in Niger, in collaboration with other partners. All countries have now completed their surveys, which have generated a considerable amount of useful information about fuel wood and fodder supplies. For Ouagadougou (population 960000 in 2000), it is estimated that 225,004 tons of fuel wood and 6708 tons of charcoal per year are transported to the city. The average price of firewood was approximately 21 F CFA per kg, and charcoal was 60 – 110 F CFA per kg. Sellers can achieve a substantial income from sales. The large quantities of fuel imported into Ouagadougou highlight the pressure on fuel resources. This is further indicated by the observations in Niger, where wood cutters cut an average of 27 steres per month, and each village can have 40 – 80 woodcutters. In Mali, annual wood fuel consumption averages about 0.5 ton per capita, and collection of a cart load of wood can involve a journey of 30 km and 3 days. Increasing numbers of grazing cattle are creating conflicts between different land uses. Assessments of fuel wood quality and palatability to animals have been made in Mali. Work package 6 Soil and plant nutrition Nutrient contents of irrigation water and soil nutrient status are being monitored at each site. In Mali, studies showed that pesticide levels were not significant, but that there was sometimes a build up of ammonium and turbidity in water flowing out of the plantation. In Burkina Faso microbiological analyses showed that the water treatment was successful in reducing levels of bacteria. Analyses have continued in all countries and no problems have been detected. Work package 7 Planting stock quality Studies have been conducted in Burkina Faso and Mali. Using various parameters of planting stock quality (shoot: root ratio, sturdiness quotient, Dickson’s Quality Index), considerable variations in quality have been identified, between species, production methods and between partners testing the same species. In Burkina Faso, a previous pot experiment was planted out. Previous effects of inoculation, substrate and pot size were no longer evident, however there was considerable variation between species in growth. At the time of planting, there were considerable differences in shoot: root ratios between species. Work package 8 Pest monitoring and management Studies in Mali have highlighted attack by termites on Leucaena and Calliandra, causing death of experimental trees, and the susceptibility of Acacia angustissima to prolonged flooding