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Scientific Articles

Sylvatic Mosquito Diversity in Kenya-Considering Enzootic Ecology of Arboviruses in an Era of Deforestation

June 18, 2020 - 14:13 -- Open Access
Author(s): 
Gillian Eastwood, Rosemary C Sang, Joel Lutomiah, Philip Tunge, Scott C Weaver
Reference: 
Insects . 2020 Jun 3;11(6):E342

As new and re-emerging vector-borne diseases are occurring across the world, East Africa represents an interesting location, being the origin of several arboviruses with a history of urbanization and global spread. Rapid expansion of urban populations and alteration of natural habitats creates the opportunity for arboviruses to host-switch from wild, sylvatic hosts or vectors into urban transmission affecting human populations. Although mosquito surveillance regularly takes place in urban areas of Kenya, for example identifying vectors of dengue virus or malaria viruses, little work has been carried out to determine the distribution and abundance of sylvatic vectors. Here, we describe the mosquito vector species and diversity collected at twelve forest habitats of rural Kenya.

Arbuscular Mycorrhizal Fungus Rhizophagus irregularis Influences Artemisia annua Plant Parameters and Artemisinin Content under Different Soil Types and Cultivation Methods

June 18, 2020 - 11:04 -- Open Access
Author(s): 
Domokos E, Bíró-Janka B, Bálint J, Molnár K, Fazakas C, Jakab-Farkas L, Domokos J, Albert C, Mara G, Balog A
Reference: 
Microorganisms. 2020 Jun 15; 8(6):E899

Artemisinin extracted from Artemisia annua has been used efficiently in malaria treatment since 2005. In this study, the variations in plant parameters (plant biomass, glandular trichome density, essential oil total chemical content, artemisinin production, and polyphenol oxidase (PPO) activity) were tested under different soil types (Luvisol, Gleysol, Anthrosol and sterile peat) and cultivation conditions (potted plants in semi-open field, and open field experiments) for plants inoculated with arbuscular mycorrhizal fungus (AMF) Rizophagus irregularis.

High-efficiency enrichment enables identification of aptamers to circulating Plasmodium falciparum-infected erythrocytes

June 17, 2020 - 13:06 -- Open Access
Author(s): 
Oteng EK, Gu W, McKeague M
Reference: 
Sci Rep. 2020 Jun 16; 10(1):9706

Plasmodium falciparum is the causative agent of the deadliest human malaria. New molecules are needed that can specifically bind to erythrocytes that are infected with P. falciparum for diagnostic purposes, to disrupt host-parasite interactions, or to deliver chemotherapeutics. Aptamer technology has the potential to revolutionize biological diagnostics and therapeutics; however, broad adoption is hindered by the high failure rate of the systematic evolution of ligands by exponential enrichment (SELEX). Here we performed parallel SELEX experiments to compare the impact of two different methods for single-strand recovery on the efficiency of aptamer enrichment.

Methods and indicators for measuring patterns of human exposure to malaria vectors

June 17, 2020 - 13:04 -- Open Access
Author(s): 
April Monroe, Sarah Moore, Fredros Okumu, Samson Kiware, Neil F. Lobo, Hannah Koenker, Ellie Sherrard-Smith, John Gimnig and Gerry F. Killeen
Reference: 
Malaria Journal 2020 19:207, 16 June 2020

Effective targeting and evaluation of interventions that protect against adult malaria vectors requires an understanding of how gaps in personal protection arise. An improved understanding of human and mosquito behaviour, and how they overlap in time and space, is critical to estimating the impact of insecticide-treated nets (ITNs) and determining when and where supplemental personal protection tools are needed. Methods for weighting estimates of human exposure to biting Anopheles mosquitoes according to where people spend their time were first developed over half a century ago. However, crude indoor and outdoor biting rates are still commonly interpreted as indicative of human-vector contact patterns without any adjustment for human behaviour or the personal protection effects of ITNs.

Application of Functional Data Analysis to Identify Patterns of Malaria Incidence, to Guide Targeted Control Strategies

June 17, 2020 - 13:01 -- Open Access
Author(s): 
Dieng S, Michel P, Guindo A, Sallah K, Ba EH, Cissé B, Carrieri MP, Sokhna C, Milligan P, Gaudart J
Reference: 
Int J Environ Res Public Health. 2020 Jun 11;17(11):E4168

We introduce an approach based on functional data analysis to identify patterns of malaria incidence to guide effective targeting of malaria control in a seasonal transmission area. Using functional data method, a smooth function (functional data or curve) was fitted from the time series of observed malaria incidence for each of 575 villages in west-central Senegal from 2008 to 2012. These 575 smooth functions were classified using hierarchical clustering (Ward’s method), and several different dissimilarity measures.

NOT Open Access | Heterologous Expression, Purification, and Functional Analysis of the Plasmodium falciparum Phosphatidylinositol 4-Kinase IIIß

June 17, 2020 - 12:59 -- NOT Open Access
Author(s): 
Sternberg AR, Roepe PD
Reference: 
Biochemistry. 2020 Jun 16

Recently we heterologously expressed, purified, and analyzed the function of the sole Plasmodium falciparum phosphatidylinositol 3-kinase (PI3K), found that the enzyme is a "class III" or "Vps34" PI3K, and that it is irreversibly inhibited by Fe2+-mediated covalent, nonspecific interactions with the leading antimalarial drug dihydroartemisinin (Hassett M. R., et al. (2017) Biochemistry 56, 4335-4345).

Variations in killer-cell immunoglobulin-like receptor and human leukocyte antigen genes and immunity to malaria

June 17, 2020 - 12:57 -- Open Access
Author(s): 
Tukwasibwe S, Nakimuli A, Colucci F, et al.
Reference: 
Cell Mol Immunol. 2020 Jun 15

Malaria is one of the deadliest infectious diseases in the world. Immune responses to Plasmodium falciparum malaria vary among individuals and between populations. Human genetic variation in immune system genes is likely to play a role in this heterogeneity. Natural killer (NK) cells produce inflammatory cytokines in response to malaria infection, kill intraerythrocytic Plasmodium falciparum parasites by cytolysis, and participate in the initiation and development of adaptive immune responses to plasmodial infection.

Ultrastructural alterations in Plasmodium falciparum induced by chalcone derivatives

June 17, 2020 - 12:54 -- Open Access
Author(s): 
Sinha S, Radotra BD, Medhi B, Batovska DI, Markova N, Sehgal R
Reference: 
BMC Res Notes. 2020 Jun 15; 13(1):290

Chalcones (1, 3-diaryl-2-propen-1-ones) and their derivatives are widely explored from the past decade for its antimalarial activity. To elucidate their mechanism of action on the malaria parasite, the ultrastructural changes with the action of these derivatives in different organelles of the parasite were studied in vitro. Infected RBCs [CQ sensitive (MRC-2) and CQ resistant (RKL-9) Plasmodium strain] were treated with three chalcone derivatives 1, 2 and 3 and standard drugs, i.e., CQ and artemisinin at twice their respective IC50 values for 24 h and then harvested, washed, fixed, embedded and stained to visualize ultra-structure changes before and after intervention of treatment under in vitro condition through transmission electron microscope.

Influx of diverse, drug resistant and transmissible Plasmodium falciparum into a malaria-free setting in Qatar

June 17, 2020 - 12:52 -- Open Access
Author(s): 
Al-Rumhi A, Al-Hashami Z, Al-Hamidhi S, Gadalla A, Naeem R, Ranford-Cartwright L, Pain A, Sultan AA, Babiker HA
Reference: 
BMC Infect Dis. 2020 Jun 15; 20(1):413

Successful control programs have impeded local malaria transmission in almost all Gulf Cooperation Council (GCC) countries: Qatar, Bahrain, Kuwait, Oman, the United Arab Emirates (UAE) and Saudi Arabia. Nevertheless, a prodigious influx of imported malaria via migrant workers sustains the threat of local transmission. Here we examine the origin of imported malaria in Qatar, assess genetic diversity and the prevalence of drug resistance genes in imported Plasmodium falciparum, and finally, address the potential for the reintroduction of local transmission.

NOT Open Access | Isolation and transcriptomic analysis of Anopheles gambiae oenocytes enables the delineation of hydrocarbon biosynthesis

June 17, 2020 - 12:51 -- NOT Open Access
Author(s): 
Grigoraki L, Grau-Bové X, Carrington Yates H, Lycett GJ, Ranson H
Reference: 
Elife. 2020 Jun 15;9:e58019

The surface of insects is coated in cuticular hydrocarbons (CHCs); variations in the composition of this layer affect a range of traits including adaptation to arid environments and defence against pathogens and toxins. In the African malaria vector, Anopheles gambiae quantitative and qualitative variance in CHC composition have been associated with speciation, ecological habitat and insecticide resistance.

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