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Vivax malaria is an infectious disease caused by Plasmodium vivax, a parasitic protozoan transmitted by female Anopheline mosquitoes. Historically, vivax malaria has often been regarded as a benign self-limiting infection due to the observation of low parasitemia in Duffy-positive patients in endemic transmission areas and the virtual absence of infections in Duffy-negative individuals in Sub Saharan Africa. However, the latest estimates show that the burden of the disease is not decreasing in many countries and cases of vivax infections in Duffy-negative individuals are increasingly reported throughout Africa. This raised questions about the accuracy of diagnostics and the evolution of interactions between humans and parasites. For a long time, our knowledge on P. vivax biology has been hampered due to the limited access to biological material and the lack of robust in vitro culture methods. Consequently, little is currently known about P. vivax blood stage invasion mechanisms. The introduction of omics technologies with novel and accessible techniques such as third generation sequencing and RNA sequencing at single cell level, two-dimensional electrophoresis, liquid chromatography, and mass spectrometry, has progressively improved our understanding of P. vivax genetics, transcripts, and proteins. This review aims to provide broad insights into P. vivax invasion mechanisms generated by genomics, transcriptomics, and proteomics and to illustrate the importance of integrated multi-omics studies.

AbstractBackgroundCowpea is a highly inbred crop. It is part of a crop-weed complex, whose origin and dynamics is unknown, which is distributed across the African continent. This study examined outcrossing rates and genetic structures in 35 wild cowpea (Vigna unguiculata ssp. unguiculata var. spontanea) populations from West Africa, using 21 isozyme loci, 9 of them showing polymorphism.ResultsOutcrossing rates ranged from 1% to 9.5% (mean 3.4%), which classifies the wild cowpea breeding system as primarily selfing, though rare outcrossing events were detected in each population studied. Furthermore, the analyses of both the genetic structure of populations and the relationships between the wild and domesticated groups suggest possibilities of gene flow that are corroborated by field observations.ConclusionsAs expected in a predominantly inbred breeding system, wild cowpea shows high levels of genetic differentiation and low levels of genetic diversity within populations. Gene flow from domesticated to wild cowpea does occur, although the lack of strong genetic swamping and modified seed morphology in the wild populations suggest that these introgressions should be rare.

Author(s): Arjen E. vant Hof [1]; Pascal Campagne [1]; Daniel J. Rigden [1]; Carl J. Yung [1]; Jessica Lingley [1]; Michael A. Quail [2]; Neil Hall [1]; Alistair C. Darby [...]

Questions Can shrub and tree seedlings be reintroduced into an extremely harsh environment through transplantation? Does the growth strategy of species affect their survival? What factors influence transplantation success? Do transplanted species influence their immediate vicinity, e.g. promote native species colonization? Location Campos Rupestres, Minas Gerais, Brazil. Methods We studied the reintroduction of four native tree and 14 native shrub species. Their transplantation success (survival, growth and reproduction) and their impact on their immediate vicinity (understorey composition, soil surface indicators, e.g. cover of moss, biological crust, bare ground, litter, herbaceous cover and soil characteristics) were assessed 4.5 yrs after transplantation. Results While some transplanted species had low survival (<30%), half of them had survival of >78% 4.5 yrs after transplantation. Plant growth was barely correlated with transplantation success in such a harsh environment. Transplanted species did not influence soil and understorey plant composition but significantly impacted soil surface indicators. The shrub species with higher survival usually allowed establishment of an understorey herbaceous cover, which may increase soil erosion control. This is also true for some species for which the survival was <40%: Diplusodon orbicularis (survival: 39%) and Lavoisiera campos-portoana (37%). Crown volume had a direct effect on light reaching the soil (e.g. Jacaranda caroba or Collaea cipoensis had a less dense canopy more permeable to light, allowing the development of understorey species). On the other hand, crown volume was positively correlated with amount of litter: Fabaceae, e.g. Chamaecrista semaphora and Mimosa foliolosa, had denser canopy and produced a thick layer of litter, limiting herbaceous species establishment. Three tree species ( Enterolobium ellipticum, Kielmeyera petiolaris and Zeyhera tuberculosa) neither had high survival nor facilitated establishment of herbaceous cover. The layout and spacing of species and individuals must thus be considered carefully to ensure recolonization by native shrub and herbaceous species. Conclusion This study demonstrates the practical efficiency of using some species native to harsh tropical ecosystems, e.g. Campos Rupestres, to restore quarry ecosystems in terms of their transplantation success, effects on both the establishment of herbaceous species and soil conservation. [ABSTRACT FROM AUTHOR]

Pyrethroid insecticides induce an excito-repellent effect that reduces contact between humans and mosquitoes. Insecticide use is expected to lower the risk of pathogen transmission, particularly when impregnated on long-lasting treated bednets. When applied at low doses, pyrethroids have a toxic effect, however the development of pyrethroid resistance in several mosquito species may jeopardize these beneficial effects. The need to find additional compounds, either to kill disease-carrying mosquitoes or to prevent mosquito contact with humans, therefore arises. In laboratory conditions, the effects (i.e., repellent, irritant and toxic) of 20 plant extracts, mainly essential oils, were assessed on adults of Anopheles gambiae, a primary vector of malaria. Their effects were compared to those of DEET and permethrin, used as positive controls. Most plant extracts had irritant, repellent and/or toxic effects on An. gambiae adults. The most promising extracts, i.e. those combining the three types of effects, were from Cymbopogon winterianus, Cinnamomum zeylanicum and Thymus vulgaris. The irritant, repellent and toxic effects occurred apparently independently of each other, and the behavioural response of adult An. gambiae was significantly influenced by the concentration of the plant extracts. Mechanisms underlying repellency might, therefore, differ from those underlying irritancy and toxicity. The utility of the efficient plant extracts for vector control as an alternative to pyrethroids may thus be envisaged. [ABSTRACT FROM AUTHOR]

Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been adopted worldwide, notably in developing countries. In spite of their success in controlling target pests while allowing a substantial reduction of insecticide use, the sustainable control of these pest populations is threatened by the evolution of resistance. The implementation of the “high dose/refuge” strategy for managing insect resistance in transgenic crops aims at delaying the evolution of resistance to Bt crops in pest populations by promoting survival of susceptible insects. However, a crucial condition for the “high dose/refuge” strategy to be efficient is that the inheritance of resistance should be functionally recessive. Busseola fusca developed high levels of resistance to the Bt toxin Cry 1Ab expressed in Bt corn in South Africa. To test whether the inheritance of B. fusca resistance to the Bt toxin could be considered recessive we performed controlled crosses with this pest and evaluated its survival on Bt and non-Bt corn. Results show that resistance of B. fusca to Bt corn is dominant, which refutes the hypothesis of recessive inheritance. Survival on Bt corn was not lower than on non-Bt corn for both resistant larvae and the F1 progeny from resistant × susceptible parents. Hence, resistance management strategies of B. fusca to Bt corn must address non-recessive resistance. [ABSTRACT FROM AUTHOR]

Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been adopted worldwide, notably in developing countries. In spite of their success in controlling target pests while allowing a substantial reduction of insecticide use, the sustainable control of these pest populations is threatened by the evolution of resistance. The implementation of the “high dose/refuge” strategy for managing insect resistance in transgenic crops aims at delaying the evolution of resistance to Bt crops in pest populations by promoting survival of susceptible insects. However, a crucial condition for the “high dose/refuge” strategy to be efficient is that the inheritance of resistance should be functionally recessive. Busseola fusca developed high levels of resistance to the Bt toxin Cry 1Ab expressed in Bt corn in South Africa. To test whether the inheritance of B. fusca resistance to the Bt toxin could be considered recessive we performed controlled crosses with this pest and evaluated its survival on Bt and non-Bt corn. Results show that resistance of B. fusca to Bt corn is dominant, which refutes the hypothesis of recessive inheritance. Survival on Bt corn was not lower than on non-Bt corn for both resistant larvae and the F1 progeny from resistant × susceptible parents. Hence, resistance management strategies of B. fusca to Bt corn must address non-recessive resistance. [ABSTRACT FROM AUTHOR]

Background: The dynamics of SARS-CoV-2 alpha variant shedding and immune responses at the nasal mucosa remain poorly characterised., Methods: We measured infectious viral release, antibodies and cytokines in 426 PCR+ nasopharyngeal swabs from individuals harboring non-alpha or alpha variants., Findings: With both lineages, viral titers were variable, ranging from 0 to >10 6  infectious units. Rapid antigenic diagnostic tests were positive in 94% of samples with infectious virus. 68 % of individuals carried infectious virus within two days after onset of symptoms. This proportion decreased overtime. Viable virus was detected up to 14 days. Samples containing anti-spike IgG or IgA did not generally harbor infectious virus. Ct values were slightly but not significantly lower with alpha. This variant was characterized by a fast decrease of infectivity overtime and a marked release of 13 cytokines (including IFN-b, IP-10 and IL-10)., Interpretation: The alpha variant displays modified viral decay and cytokine profiles at the nasopharyngeal mucosae during symptomatic infection., Funding: This retrospective study has been funded by Institut Pasteur, ANRS, Vaccine Research Institute, Labex IBEID, ANR/FRM and IDISCOVR, Fondation pour la Recherche Médicale., Competing Interests: Declaration of Competing Interest L.G., I.S., T.B., F.G.-B., and O.S. have a patent US 63/020,063 entitled “S-Flow: a FACS-based assay for serological analysis of SARS-CoV2 infection” pending. The other authors have no conflict of interests to disclose., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)