Block Transmission Research Articles

Screening of the activity of sixty essential oils against plasmodium early mosquito stages in vitro and machine learning analysis reveals new putative inhibitors of malaria parasites

Malaria, an infectious disease with a tremendous impact on human health is caused by Plasmodium parasites, and transmitted by Anopheles mosquitoes. New approaches to control the disease involve transmission blocking strategies aiming to target the parasite in the mosquito. Here, we investigated the putative inhibitory activity of essential oils and their components on the early mosquito stages of the parasite. We employed an in vitro assay of gametocyte-to-ookinete development of the rodent model parasite Plasmodium berghei combined with high content screening. 60 essential oils with known composition were tested. The results revealed that fifteen EOs had inhibitory activity. Furthermore, a machine learning approach was used to identify the putative inhibitory components. Five of the most important chemical components indicated by the machine learning-based models were actually confirmed by the experimental approach. This combined approach was used for the first time to identify the potential transmission blocking activity of essential oils and single components at the zygote and ookinete stages.

Optimisation of adult Anopheles funestus blood-feeding on an artificial membrane feeding system

Malaria is one of the most severe vector-borne diseases caused by Plasmodium parasites and transmitted by Anopheles mosquitoes. Laboratory-reared anophelines are essential to advance research needed to reduce or eliminate malaria. The success of laboratory rearing as well as studies on parasite-mosquito transmission, is advanced by using an artificial membrane feeding systems. These require the optimisation of mosquito feeding to ensure that an optimal number of mosquitoes feed, thereby enabling successful reproduction or research sample sizes. In this study, various parameters such as the type of artificial membrane, density of adults in the feeding cup, age of the mosquito, duration of starvation, method of starvation, the volume of blood meal, duration of feeding, feeding in the light or dark and the effect of lactic acid were evaluated to determine their impact on the feeding rate of a main African malaria vector, Anopheles funestus. By optimising the artificial membrane feeding parameters, an increase in the feeding rate of the An. funestus mosquitoes was observed. The results obtained from these parameters increased the feeding rate of An. funestus above 50%. However, feeding rates were not significantly increased by the type of membrane, mosquito density, the volume of blood meal, duration of feeding and the addition of lactic acid to the cattle intestine membrane. Therefore, this study provides information on suitable conditions for adult mosquito feeding that allows for successful laboratory rearing and colony maintenance. Furthermore, it provides additional information for research studies that are dependent on blood-feeding, such as transmission blocking studies, endectocide studies etc.

Turkish validity and reliability study of the Infection Prevention Behavior Scale of Individuals (IPBS-I)

Objective: This study aimed to evaluate the validity and reliability of the Infection Prevention Behavior Scale of Individuals (IPBS-I) among Turkish individuals. Materials and Methods: This was a methodological validity and reliability study. A total of 309 individuals between the ages of 18-65 who met the inclusion criteria were enrolled. The IPBS-I was translated into Turkish using the translation-back-translation technique. Data were collected via the Personal Information Form (PIF), Turkish version of the IPBS-I (IPBS-I-TR), and Protective Behaviors Towards COVID-19 Scale (PBCS). Two weeks later, IPBS-I-TR evaluation was repeated. Confirmatory Factor Analysis (CFA) was performed for construct validity, and the PBCS was applied for criterion validity. Its reliability was evaluated using internal consistency, item analysis, and test-retest reliability. Statistical significance was set at p< 0.05. Results: In total, 309 individuals (183 women and 126 men) were enrolled in the study. The mean IPBS-I-TR was 4.09±0.64. The CFA results revealed ᵡ2=167.12, SD=51, and p=0.0001. It was determined that x²/SD was 3.277 in the model and that the model was compatible. The Standardized Root Mean Square Residual (S-RMR)=0.051, Comparative Fit Index (CFI)=0.929, Goodness of Fit Index (GFI)=0.917, and Root Mean Square Error of Approximation (RMSEA)=0.086 were determined to be within the acceptable range. The CFA supported the three-factor structure of the scale. The correlation coefficient with the PBCS was 0.639, confirming the criterion validity of the scale. The Cronbach's alpha coefficients of the entire scale and three subscales (“Blocking the Pathogen,” “Blocking Transmission,” and “Improving Immunity”) were 0.832, 0.826, and 0.725, respectively. The test-retest reliability of the entire scale and the three subscales was excellent (>0.80). Conclusion: The Turkish version of the IPBS-I was confirmed to have good reliability and validity for evaluating infection-prevention behaviors in Turkish society.

Clinical Experience with Commissioning a GRID Collimator for Spatially Fractionated Radiation Therapy

In this study, we report our physics commissioning experience for clinically implementing a GRID collimator based Spatially Fractionated Radiation Therapy (SFRT). For SFRT commissioning, we utilized a commercially available brass GRID collimator (DotDecimal, Sanford, FL) that is mounted on a blocking tray for positioning into the accessory mount of the Linac. The brass GRID is 7.62 cm thick and weighs 15.8 kg. The GRID has a total of 149 divergent holes arranged in a hexagonal pattern (1.43 cm in diameter and hole-centers spaced at 2.11 cm when projected at the isocenter distance). The GRID encompasses a maximum field size of 25 × 25 cm at the isocenter. A commercial 48 × 48 × 48 cm water phantom scanning system was used to collect GRID output factors (GRID field to open field ratio), depth dose and beam profile data. Output measurements were performed using a 0.13 cm3 active volume ion-chamber and beam scans were obtained with a diode detector. Data was collected for both flattening and flattening-free beams of nominal energies 6 MV and 10 MV photons. The measurement depths were at dmax (1.5 cm for 6 MV and 2.5 cm for 10 MV), 5-cm and 10-cm respectively. For each energy and depth of measurement, collimator settings were varied from 5 × 5 cm to 28 × 28 cm. From scan profiles at different depths, the valley (lowest) to peak (highest) dose ratios (VPDR) were calculated. A commercial treatment planning system (TPS) was used to test the accuracy of dose calculations with GRID. This was accomplished by importing vendor generated DICOM RT file into the TPS. A block transmission factor of 7% for 6 MV and 10.2% for 10 MV energy beams were applied. All measured data were compared with corresponding TPS calculated data. Test patient treatment plans with GRID were created in TPS and planned distributions were verified using a commercial detector array with 2.5 mm detector spacing. The VPDR, expressed as %, are presented in Table 1. Measured and TPS calculated output factors agreed within 2% for 6 MV and within 3% for 10 MV photon beams. Percent depth doses were lower in magnitude for GRID field compared to open field for all energies studied (for e.g., 6 MV depth dose at 10 cm depth for 10 cm x10cm field 62% for GRID field vs. 66% for open field). Measured and calculated GRID beam profiles agreed within 5% dose difference and 1 mm distance-to agreement. For all test cases, the planned vs. measured dose distributions passed at an average gamma passing rate of 96.5% using a 3% dose difference/ 3 mm distance to agreement and 10% threshold criteria. The Dot Decimal GRID collimator provides a simple way of achieving SFRT in the clinic, albeit heavy to use and has an irradiation field size limitation of 25 cm × 25 cm.

Pharmacokinetics of single low dose primaquine in Ugandan and Congolese children with falciparum malaria

There are no pharmacokinetic data of single low dose primaquine (SLDPQ) as transmission blocking in African children with acute Plasmodium falciparum and glucose-6-phosphate dehydrogenase deficiency (G6PDd). Primaquine pharmacokinetics of age-dosed SLDPQ (shown previously to be gametocytocidal with similar tolerability as placebo) were characterised in falciparum-infected Ugandan and Congolese children aged 6 months to 11 years, treated on admission with standard 3-day dihydroartemisinin-piperaquine or artemether-lumefantrine plus SLDPQ: 6m-<1y: 1.25mg, 1-5y: 2.5mg, 6-9y: 5mg, 10-11y: 7.5mg. LC-MS/MS-measured plasma primaquine and carboxyprimaquine (baseline, 1, 1.5, 2, 4, 8, 12, 24h) were analysed by noncompartmental analysis. Multivariable linear regression modelled associations between covariates, including cytochrome-P450 2D6 metaboliser status, and outcomes. 258 children (median age 5 [interquartile range (IQR) 3-7]) were sampled; 8 (3.1%) with early vomiting were excluded. Primaquine doses of 0.10-0.40 (median 0.21, IQR 0.16-0.25) mg base/kg resulted in primaquine maximum plasma concentrations (Cmax) of 2.3-447 (median 103.0, IQR 72.1-140.0) ng/mL between 1.0 and 8.0 (median 2) hours (Tmax) and median areas under the drug concentration curves (AUC0-last) 730.2 (6m-<1y, n=12), 582.8 (1-5y, n=126), 871.1 (6-9y, n=80), and 931.0 (10-11y, n=32) ng∗h/mL. Median elimination half-live (T½) was 4.7 (IQR 3.8-5.6) hours. Primaquine clearance/kg peaked at 18 months, plateauing at 4y. Increasing CYP2D6 metaboliser activity score [poor (3/250), intermediate (52/250), normal (150/250), ultrarapid (5/250), indeterminate (40/250)] and baseline haemoglobin were significantly associated with a lower primaquine AUC0-last,which increased with increasing mg/kg dose and age but was independent of the artemisinin treatment used. Age-dosed SLDPQ resulted in variable primaquine exposure that depended on bodyweight-adjusted dose, age, baseline haemoglobin and CYP2D6 metaboliser status, but not on dihydroartemisinin-piperaquine or artemether-lumefantrine. These data support age-dosed SLDPQ for transmission blocking in sub-Saharan Africa. This work was cofunded by the UK Medical Research Council, Wellcome Trust, and UK Aid through the Global Health Trials (grant reference MR/P006973/1). The funders had no role in the study design, execution, and analysis and decisions regarding publication.

Interconnected square splits ring resonator based single negative metamaterial for 5G (N258, N257, N260 and N259) band sensor/EMI shielding/and antenna applications

This article proposed a new triple-band transmission block metamaterial (MTM) for 5G mm-wave applications. The peak transmission-blocking attributes are achieved at 27.09 GHz, 38.71 GHz, and 41.81 GHz frequency by interconnected square split ring resonators (ISSRR). A thin Rogers RT5880 substrate material of thickness 0.79 mm is employed to design the MTM structure, and the unit cell dimension is 5 × 5 mm2. The designed metamaterial shows a −10 dB transmission coefficient (S21) from 24.60 to 28.47 GHz, 36.50–39.65 GHz and 40.77–44 GHz frequency bands. The design evolution, metamaterial properties, surface current distribution, electric field, magnetic field, and equivalent circuit model are investigated to understand the transmission-blocking property of the MTM. The simulated results of the MTM are validated by measurement of the fabricated prototype, and both results agree well. The transmission-blocking attributes lead the proposed MTM as a potential candidate for different fields like EMI shielding, sensing, and antenna performance enhancement. The dielectric sensor performance of the MTM structure is investigated for different dielectric materials. Besides, MIMO antenna performances are also investigated, and gains of 1–3 dBi, isolations of 5–10 dB, and the radiation pattern deflection angle of 45˚ are enhanced by the proposed MTM. These significant features and applications of the proposed MTM make it a special candidate for 5G mm-wave applications.

Performance of Broadcast Channel Using Hierarchical Modulation in OFDM Downlink

This paper proposes a multiple code block transmission scheme using hierarchical modulation (HM) for a broadcast channel in the orthogonal frequency division multiplexing downlink. We investigate the average bit error rate (BER) performance of two-layer HM using 16 quadrature amplitude modulation (QAM) and three-layer HM using 64QAM in multipath Rayleigh fading channels. In multiple code block transmission using HM, the basic information bits are demodulated and decoded to all users within a cell that satisfy the bit error rate (BER) requirement. Hence, we investigate non-uniform QAM constellations to find one that suppresses the loss in the average BER of the basic information bits for HM to a low level compared to that using the original constellation in which only the basic information bits are transmitted while simultaneously minimizing the loss in the average BER of the basic information bits for the secondary and tertiary information bits from the original constellations in which the information bits of the respective layers are transmitted alone. Based on the path loss equations in the Urban Macro and Rural Macro scenarios, we also investigate the maximum distance from a base station (BS) for the information bits of each layer to attain the required average received signal-to-noise power ratio that achieves the average BER of 10-3.

Effect of aminergic signaling on the humoral innate immunity response of Drosophila.

Biogenic amines are crucial signaling molecules that modulate various physiological life functions both in vertebrates and invertebrates. In humans, these neurotransmitters influence the innate and adaptive immunity systems. In this work, we analyzed whether the aminergic neurotransmission of dopamine, serotonin, and octopamine could have an impact on the humoral innate immune response of Drosophila melanogaster. This is a powerful model system widely used to uncover the insect innate immunity mechanisms which are also conserved in mammals. We found that the neurotransmission of all these amines positively modulates the Toll-responsive antimicrobial peptide (AMP) drosomycin (drs) gene in adult flies infected with the Micrococcus luteus bacterium. Indeed, we showed that either blocking the neurotransmission in their specific aminergic neurons by expressing shibirets (Shits) or silencing the vesicular monoamine transporter gene (dVMAT) by RNAi caused a significantly reduced expression of the Toll-responsive drs gene. However, upon M. luteus infection, the block of aminergic transmission did not alter the expression of AMP attacin genes responding to the immune deficiency (Imd) and Toll pathways. Overall, our results not only reveal a neuroimmune function for biogenic amines in humoral immunity but also further highlight the complexity of the network controlling AMP gene regulation.

Plasmodium microtubule-binding protein EB1 is critical for partitioning of nuclei in male gametogenesis.

Sexual reproduction of the malaria parasites is critical for their transmission to a mosquito vector. Several signaling molecules, such as kinases and phosphatases, are known to regulate this process. We previously demonstrated that Plasmodium falciparum (Pf) Ca2+-dependent protein kinase 4 (CDPK4) and serine/arginine-rich protein kinase 1 (SRPK1) are critical for axoneme formation during male gametogenesis, with genetic deletion of either gene causing a complete block in parasite transmission to the mosquito. A comparative phospho-proteome analysis of Pfcdpk4- and RNA-seq analysis of Pfsrpk1- gametocytes showed that these kinases regulate similar biological processes linked to both microtubule (MT) dynamics and cell motility. One of these proteins was a nuclear MT-associated End Binding protein 1 (EB1), which was hypophosphorylated in Pfcdpk4- gametocytes. To study the functional relevance of EB1, we created gene deletion parasites for EB1. We further demonstrate that Pfeb1- parasites like WT NF54 parasites proliferate normally as asexuals and undergo gametocytogenesis and gametogenesis. Strikingly, these parasites suffer a severe defect in nuclear segregation and partitioning of nuclei into emerging microgametes. Further genetic crosses utilizing male- and female-sterile parasites revealed that Pfeb1- parasites only suffer a male fertility defect. Overall, our study reveals an essential function for PfEB1 in male gamete nuclear segregation and suggests a potential therapeutic avenue in the design of transmission-blocking drugs to prevent malaria transmission from humans to mosquito. IMPORTANCE Gametogenesis and subsequent gamete fusion are central to successful transmission of the malaria parasites to a female Anopheles mosquito vector and completion of the sexual phase of the parasite life cycle. Male gametogenesis involves the formation of axonemes inside male gametes from male gametocytes via active cytoskeleton remodeling. The tubulin and tubulin-binding proteins are, thus, attractive anti-malarial drug targets. In the present study, we demonstrate that a microtubule-binding protein PfEB1 is essential for male gamete fertility, specifically for the inheritance of nuclei from activated male gametocytes. Targeting PfEB1 function may provide new avenues into designing interventions to prevent malaria transmission and disease spread.

Event-based fixed-time synchronization of neural networks under DoS attack and its applications

In this paper, the fixed-time synchronization control for neural networks with discontinuous data communication is investigated. Due to the transmission blocking caused by DoS attack, it is intractable to establish a monotonically decreasing Lyapunov function like the conventional analysis of fixed-time stability. Therefore, by virtue of recursive and reduction to absurdity approaches, novel fixed-time stability criteria where the estimated upper bound of settling-time is inherently different from existing results are presented. Then, based on the developed conditions, an event-triggered control scheme that can avoid Zeno behavior is designed to achieve synchronization of master–slave neural networks under DoS attack within a prescribed time. For comparison, the established control scheme is further discussed under the case without DoS attack, and the circumstance that there is no attack or event-triggered mechanism, respectively. Simulation results are finally provided to illustrate the significant and validity of our theoretical research. Especially, in terms of encryption and decryption keys generated from the synchronization behavior of chaotic networks, we specifically discuss the application of the proposed fixed-time synchronization scheme to image and audio encryption.

A recombinant Aspergillus oryzae fungus transmitted from larvae to adults of Anopheles stephensi mosquitoes inhibits malaria parasite oocyst development

The control of malaria parasite transmission from mosquitoes to humans is hampered by decreasing efficacies of insecticides, development of drug resistance against the last-resort antimalarials, and the absence of effective vaccines. Herein, the anti-plasmodial transmission blocking activity of a recombinant Aspergillus oryzae (A. oryzae-R) fungus strain, which is used in human food industry, was investigated in laboratory-reared Anopheles stephensi mosquitoes. The recombinant fungus strain was genetically modified to secrete two anti-plasmodial effector peptides, MP2 (midgut peptide 2) and EPIP (enolase-plasminogen interaction peptide) peptides. The transstadial transmission of the fungus from larvae to adult mosquitoes was confirmed following inoculation of A. oryzae-R in the water trays used for larval rearing. Secretion of the anti-plasmodial effector peptides inside the mosquito midguts inhibited oocyst formation of P. berghei parasites. These results indicate that A. oryzae can be used as a paratransgenesis model carrying effector proteins to inhibit malaria parasite development in An. stephensi. Further studies are needed to determine if this recombinant fungus can be adapted under natural conditions, with a minimal or no impact on the environment, to target mosquito-borne infectious disease agents inside their vectors.

Assessment of the transmission blocking activity of antimalarial compounds by membrane feeding assays using natural Plasmodium falciparum gametocyte isolates from West-Africa.

Antimalarial drugs that can block the transmission of Plasmodium gametocytes to mosquito vectors would be highly beneficial for malaria elimination efforts. Identifying transmission-blocking drugs currently relies on evaluation of their activity against gametocyte-producing laboratory parasite strains and would benefit from a testing pipeline with genetically diverse field isolates. The aims of this study were to develop a pipeline to test drugs against P. falciparum gametocyte field isolates and to evaluate the transmission-blocking activity of a set of novel compounds. Two assays were designed so they could identify both the overall transmission-blocking activity of a number of marketed and experimental drugs by direct membrane feeding assays (DMFA), and then also discriminate between those that are active against the gametocytes (gametocyte killing or sterilizing) or those that block development in the mosquito (sporontocidal). These DMFA assays used venous blood samples from naturally infected Plasmodium falciparum gametocyte carriers and locally reared Anopheles gambiae s.s. mosquitoes. Overall transmission-blocking activity was assessed following a 24 hour incubation of compound with gametocyte infected blood (TB-DMFA). Sporontocidal activity was evaluated following addition of compound directly prior to feeding, without incubation (SPORO-DMFA); Gametocyte viability was retained during 24-hour incubation at 37°C when gametocyte infected red blood cells were reconstituted in RPMI/serum. Methylene-blue, MMV693183, DDD107498, atovaquone and P218 showed potent transmission-blocking activity in the TB-DMFA, and both atovaquone and the novel antifolate P218 were potent inhibitors of sporogonic development in the SPORO-DMA. This work establishes a pipeline for the integral use of field isolates to assess the transmission-blocking capacity of antimalarial drugs to block transmission that should be validated in future studies.

Structure of a transmission blocking antibody in complex with Outer surface protein A from the Lyme disease spirochete, Borreliella burgdorferi.

319-44 is a human monoclonal antibody capable of passively protecting mice against tick-mediated infection with Borreliella burgdorferi, the bacterial genospecies responsible for Lyme disease in North America. In vitro, 319-44 has complement-dependent borreliacidal activity and spirochete agglutinating properties. Here, we report the 2.2 Å-resolution crystal structure of 319-44 Fab fragments in complex with Outer surface protein A (OspA), the ~30 kDa lipoprotein that was the basis of the first-generation Lyme disease vaccine approved in the United States. The 319-44 epitope is focused on OspA β-strands 19, 20, and 21, and the loops between β-strands 16-17, 18-19, and 20-21. Contact with loop 20-21 explains competition with LA-2, the murine monoclonal antibody used to estimate serum borreliacidal activities in the first-generation Lyme disease vaccine clinical trials. A high-resolution B-cell epitope map of OspA will accelerate structure-based design of second generation OspA-based vaccines.

Responsive Sensory Evaluation to Develop Flexible Taste-Masked Paediatric Primaquine Tablets against Malaria for Low-Resource Settings.

Primaquine is an important antimalarial drug for malaria transmission blocking and radical cure, but it is not currently available in child-friendly formulations in appropriate doses. Adult-strength tablets are often crushed and dissolved in water to obtain the required dose, which exposes the drug's bitter taste. As part of the developing paediatric primaquine (DPP) project, this study adopted a responsive sensory pharmaceutics approach by integrating real-time formulation development and pre-clinical taste assessment to develop palatable, flavour-infused primaquine tablets. A design of experiment (DoE) approach was used to screen different taste-masking agents and excipient blends with trained, expert sensory assessors, with quinine hydrochloride as a model bitter tastant. The taste-masking efficacy of selected prototype formulation blends was validated with naïve assessors using the highest 15 mg primaquine dose. The mean bitterness intensity rating, measured on a discrete 11-point scale, was halved from 7.04 for the unflavoured control to 2.74-3.70 for the formulation blends. Sucralose had the biggest impact on bitterness suppression and improving palatability. Two different flavouring systems have been developed, and their acceptability in paediatric patients will be assessed as part of upcoming validation field clinical trials in Africa.

Practical Interference Exploitation Precoding Without Symbol-by-Symbol Optimization: A Block-Level Approach

In this paper, we propose a constructive interference (CI)-based block-level precoding (CI-BLP) approach for the downlink of a multi-user multiple-input single-output (MU-MISO) communication system. Contrary to existing CI precoding approaches which have to be designed on a symbol-by-symbol level, here a constant precoding matrix is applied to a collection of symbols within a given transmission block, thus significantly reducing the computational costs over traditional CI-based symbol-level precoding (CI-SLP) as the CI-BLP optimization problem only needs to be solved once per block. For both PSK and QAM modulation, we formulate an optimization problem to maximize the minimum CI effect over the block subject to a block-rather than symbol-level power budget. We mathematically derive the optimal precoding matrix for CI-BLP as a function of the Lagrange multipliers in closed form. By formulating the dual problem, the original CI-BLP optimization problem is further shown to be equivalent to a quadratic programming (QP) optimization. Numerical results validate our derivations, and show that the proposed CI-BLP scheme achieves improved performance over the traditional CI-SLP method, thanks to the relaxed power constraint over the considered block of symbol slots.

Integrated Sensing and Communications for V2I Networks: Dynamic Predictive Beamforming for Extended Vehicle Targets

We investigate sensing-assisted beamforming for vehicle-to-infrastructure (V2I) communication by exploiting integrated sensing and communications (ISAC) functionalities at the roadside unit (RSU). The RSU deploys a massive multi-input-multi-output (mMIMO) array at mmWave. The pencil-sharp mMIMO beams and fine range-resolution implicate that the point-target assumption is impractical, as the vehicle’s geometry becomes essential. Therefore, the communication receiver (CR) may never lie in the beam, even when the vehicle is accurately tracked. To tackle this problem, we consider the extended target with two novel schemes. For the first scheme, the beamwidth is adjusted in real-time to cover the entire vehicle, followed by an extended Kalman filter to predict and track the position of CR according to resolved scatterers. An upgraded scheme is proposed by splitting each transmission block into two stages. The first stage is exploited for ISAC with a wide beam. Based on the sensed results at the first stage, the second stage is dedicated to communication with a pencil-sharp beam, yielding significant communication improvements. We reveal the inherent tradeoff between the two stages in terms of their durations, and develop an optimal allocation strategy that maximizes the average achievable rate. Finally, simulations verify the superiorities of proposed schemes over state-of-the-art methods.

Novel systems to study vector-pathogen interactions in malaria.

Some parasitic diseases, such as malaria, require two hosts to complete their lifecycle: a human and an insect vector. Although most malaria research has focused on parasite development in the human host, the life cycle within the vector is critical for the propagation of the disease. The mosquito stage of the Plasmodium lifecycle represents a major demographic bottleneck, crucial for transmission blocking strategies. Furthermore, it is in the vector, where sexual recombination occurs generating "de novo" genetic diversity, which can favor the spread of drug resistance and hinder effective vaccine development. However, understanding of vector-parasite interactions is hampered by the lack of experimental systems that mimic the natural environment while allowing to control and standardize the complexity of the interactions. The breakthrough in stem cell technologies has provided new insights into human-pathogen interactions, but these advances have not been translated into insect models. Here, we review in vivo and in vitro systems that have been used so far to study malaria in the mosquito. We also highlight the relevance of single-cell technologies to progress understanding of these interactions with higher resolution and depth. Finally, we emphasize the necessity to develop robust and accessible ex vivo systems (tissues and organs) to enable investigation of the molecular mechanisms of parasite-vector interactions providing new targets for malaria control.

Intervention reducing malaria parasite load in vector mosquitoes: No impact on Plasmodium falciparum extrinsic incubation period and the survival of Anopheles gambiae.

In the fight against malaria, transmission blocking interventions (TBIs) such as transmission blocking vaccines or drugs, are promising approaches to complement conventional tools. They aim to prevent the infection of vectors and thereby reduce the subsequent exposure of a human population to infectious mosquitoes. The effectiveness of these approaches has been shown to depend on the initial intensity of infection in mosquitoes, often measured as the mean number of oocysts resulting from an infectious blood meal in absence of intervention. In mosquitoes exposed to a high intensity of infection, current TBI candidates are expected to be ineffective at completely blocking infection but will decrease parasite load and therefore, potentially also affect key parameters of vector transmission. The present study investigated the consequences of changes in oocyst intensity on subsequent parasite development and mosquito survival. To address this, we experimentally produced different intensities of infection for Anopheles gambiae females from Burkina Faso by diluting gametocytes from three natural Plasmodium falciparum local isolates and used a newly developed non-destructive method based on the exploitation of mosquito sugar feeding to track parasite and mosquito life history traits throughout sporogonic development. Our results indicate the extrinsic incubation period (EIP) of P. falciparum and mosquito survival did not vary with parasite density but differed significantly between parasite isolates with estimated EIP50 of 16 (95% CI: 15-18), 14 (95% CI: 12-16) and 12 (95% CI: 12-13) days and median longevity of 25 (95% CI: 22-29), 15 (95% CI: 13-15) and 18 (95% CI: 17-19) days for the three isolates respectively. Our results here do not identify unintended consequences of the decrease of parasite loads in mosquitoes on the parasite incubation period or on mosquito survival, two key parameters of vectorial capacity, and hence support the use of transmission blocking strategies to control malaria.

Refractory material inspired ultra-wideband solar absorber for thermoelectric photovoltaic performance enhancement with ML inspired prediction

A U-shaped Metal-Insulator-Metal (MIM) solar energy absorber is simulated, and designed in this paper. Tungsten is utilized as the base metal layer because of its transmission blocking characteristics, the SiO2 is used as a dielectric insulator and a U-shaped resonator made of titanium as a radiation absorber to achieve a near perfect Solar energy absorber as it provides the impedance matching abilities. The proposed structure is simulated over the solar spectrum which covers the wavelengths from 0.2 to 2.5 µm which includes the ultraviolet (UV) to near infrared (NIR) bands, the absorbed energy is of 94.52%, 97.06%, and 96.67%, respectively. Furthermore, the additional investigation under solar radiation is conducted and the proposed structure is absorbing most of the energy while the minimal amount is missed in visible range. The main contribution of this work lies in its broadband absorption spectrum which is achieved employing a very simple and easy to fabricate structure. In addition, the structure also achieves the angle and polarization insensitiveness. The major contribution is the prediction of absorption at an intermediate wavelengths with locally weighted linear regression with a R2 score of 0.9999. The proposed structure can be used for the efficiency enhancement of thermoelectric photovoltaic devices.

Using qPCR to compare the detection of Plasmodium vivax oocysts and sporozoites in Anopheles farauti mosquitoes between two DNA extraction methods

BackgroundCurrently, the gold standard to assess parasite developmental stages in mosquitoes is light microscopy. Microscopy can miss low-density infections, is time-consuming and not species-specific. Enzyme-linked immunosorbent assay (ELISA) has been the alternative technique to evaluate the infectivity of mosquitoes especially in field studies however it is semi-quantitative. Molecular techniques that have been used to detect the mosquito stages of malaria parasites including P. vivax. Here, we present a quantitative real-time assay (qPCR) that can be used to detect low-density P. vivax oocyst and sporozoite infections while comparing parasites extracted by the conventional DNA extraction and heating methods.MethodsColony reared Anopheles farauti mosquitoes were exposed to blood samples collected from infected individuals using a direct membrane feeding assay. The fully fed mosquitoes were kept for 7 and 14 days post-feed before dissection to confirm presence of oocysts and sporozoites. Infected mosquito guts and the salivary glands (with the head and thorax) were stored and DNA was extracted either by heating or by performing conventional column-based DNA extraction. Following DNA extraction the infected samples were subjected to qPCR to detect P. vivax parasites.ResultsDNA extraction of 1 or more oocysts by heating resulted in an overall sensitivity of 78% (57/73) and single oocysts infections were detected with a sensitivity of 82% (15/17) in the heating arm. We observed a 60% (18/30) sensitivity with sporozoites where DNA was extracted using the conventional DNA extraction method. We show that the heating method significantly improved the detection of oocysts over conventional DNA extraction. There was no significant difference in the DNA copy numbers when comparing the detection of oocysts from the conventional DNA extraction versus heating. However, we observed that the DNA copy numbers of the sporozoites detected in the heating arm was significantly higher than in the conventional DNA extraction arm.ConclusionWe have adapted a qPCR assay which, when coupled with heating to release DNA reduces sample processing time and cost. Direct qPCR after heating will be a useful tool when investigating transmission blocking vaccines or antimalarials or when evaluating field caught mosquitoes for the presence of malaria parasites.