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Transmission from an infected mosquito to a host is an essential process in the life cycle of mosquito-borne flaviviruses. Numerous studies have demonstrated that mosquito saliva facilitates viral transmission. Here we find that a saliva-specific protein, named Aedes aegypti venom allergen-1 ( Aa VA-1), promotes dengue and Zika virus transmission by activating autophagy in host immune cells of the monocyte lineage. The AG6 mice ( ifnar1 –/– ifngr1 –/– ) bitten by the virus-infected Aa VA-1-deficient mosquitoes present a lower viremia and prolonged survival. Aa VA-1 intracellularly interacts with a dominant negative binder of Beclin-1, known as leucine-rich pentatricopeptide repeat-containing protein (LRPPRC), and releases Beclin-1 from LRPPRC-mediated sequestration, thereby enabling the initialization of downstream autophagic signaling. A deficiency in Beclin-1 reduces viral infection in mice and abolishes Aa VA-1-mediated enhancement of ZIKV transmission by mosquitoes. Our study provides a mechanistic insight into saliva-aided viral transmission and could offer a potential prophylactic target for reducing flavivirus transmission. Mosquito saliva affects transmission of flaviviruses, but underlying mechanisms are incompletely understood. Here, the authors show that Aedes aegypti venom allergen-1 ( Aa VA-1) promotes dengue and Zika virus transmission by activating autophagy in host immune cells of the monocyte lineage.

Background Mitochondrial dysfunction and toxic protein aggregates have been shown to be key features in the pathogenesis of neurodegenerative diseases, such as Parkinson’s disease (PD). Functional analysis of genes linked to PD have revealed that the E3 ligase Parkin and the mitochondrial kinase PINK1 are important factors for mitochondrial quality control. PINK1 phosphorylates and activates Parkin, which in turn ubiquitinates mitochondrial proteins priming them and the mitochondrion itself for degradation. However, it is unclear whether dysregulated mitochondrial degradation or the toxic build-up of certain Parkin ubiquitin substrates is the driving pathophysiological mechanism leading to PD. The iron-sulphur cluster containing proteins CISD1 and CISD2 have been identified as major targets of Parkin in various proteomic studies. Methods We employed in vivo Drosophila and human cell culture models to study the role of CISD proteins in cell and tissue viability as well as aged-related neurodegeneration, specifically analysing aspects of mitophagy and autophagy using orthogonal assays. Results We show that the Drosophila homolog Cisd accumulates in Pink1 and parkin mutant flies, as well as during ageing. We observed that build-up of Cisd is particularly toxic in neurons, resulting in mitochondrial defects and Ser65-phospho-Ubiquitin accumulation. Age-related increase of Cisd blocks mitophagy and impairs autophagy flux. Importantly, reduction of Cisd levels upregulates mitophagy in vitro and in vivo, and ameliorates pathological phenotypes in locomotion, lifespan and neurodegeneration in Pink1/parkin mutant flies. In addition, we show that pharmacological inhibition of CISD1/2 by rosiglitazone and NL-1 induces mitophagy in human cells and ameliorates the defective phenotypes of Pink1/parkin mutants. Conclusion Altogether, our studies indicate that Cisd accumulation during ageing and in Pink1/parkin mutants is a key driver of pathology by blocking mitophagy, and genetically and pharmacologically inhibiting CISD proteins may offer a potential target for therapeutic intervention. Graphical Abstract

With dengue virus (DENV) becoming endemic in tropical and subtropical regions worldwide, there is a pressing global demand for effective strategies to control the mosquitoes that spread this disease. Recent advances in genetic engineering technologies have made it possible to create mosquitoes with reduced vector competence, limiting their ability to acquire and transmit pathogens. Here we describe the development of Aedes aegypti mosquitoes synthetically engineered to impede vector competence to DENV. These mosquitoes express a gene encoding an engineered single-chain variable fragment derived from a broadly neutralizing DENV human monoclonal antibody and have significantly reduced viral infection, dissemination, and transmission rates for all four major antigenically distinct DENV serotypes. Importantly, this is the first engineered approach that targets all DENV serotypes, which is crucial for effective disease suppression. These results provide a compelling route for developing effective genetic-based DENV control strategies, which could be extended to curtail other arboviruses.

Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5±8.4 µm measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments.

Zika virus (ZIKV) is a mosquito-borne flavivirus that predominantly circulates between humans and Aedes mosquitoes. Clinical studies have shown that Zika viruria in patients persists for an extended period, and results in infectious virions being excreted. Here, we demonstrate that Aedes mosquitoes are permissive to ZIKV infection when breeding in urine or sewage containing low concentrations of ZIKV. Mosquito larvae and pupae, including from field Aedes aegypti can acquire ZIKV from contaminated aquatic systems, resulting in ZIKV infection of adult females. Adult mosquitoes can transmit infectious virions to susceptible type I/II interferon receptor-deficient ( ifnagr-/- ) C57BL/6 (AG6) mice. Furthermore, ZIKV viruria from infected AG6 mice can causes mosquito infection during the aquatic life stages. Our studies suggest that infectious urine could be a natural ZIKV source, which is potentially transmissible to mosquitoes when breeding in an aquatic environment. Here the authors show that Aedes mosquitoes can acquire ZIKV by breeding in contaminated aquatic systems, and that these infected mosquitoes can transmit ZIKV to susceptible mice. This suggests that human urine containing aquatic environments could contribute to ZIKV transmission.

The mitochondrion is a highly dynamic organelle that is critical for energy production and numerous metabolic processes. Drosophila Chchd2 , a homolog of the human disease-related genes CHCHD2 and CHCHD10 , encodes a mitochondrial protein. In this study, we found that loss of Chchd2 in flies resulted in progressive degeneration of photoreceptor cells and reduced muscle integrity. In the flight muscles of adult Chchd2 mutants, some mitochondria exhibited curling cristae and a reduced number of cristae compared to those of controls. Overexpression of Chchd2 carrying human disease-related point mutations failed to fully rescue the mitochondrial defects in Chchd2 mutants. In fat body cells, loss of Chchd2 resulted in fragmented mitochondria that could be partially rescued by Marf overexpression and enhanced by Opa1 RNAi. The expression level of Opa1 was reduced in Chchd2 mutants and increased when Chchd2 was overexpressed. The chaperone-like protein P32 co-immunoprecipitated with Chchd2 and YME1L, a protease known to processes human OPA1. Moreover, the interaction between P32 and YME1L enhanced YME1L activity and promoted Opa1 degradation. Finally, Chchd2 stabilized Opa1 by competing with P32 for YME1L binding. We propose a model whereby Chchd2 regulates mitochondrial morphology and tissue homeostasis by fine-tuning the levels of OPA1.

Platelet-rich plasma (PRP) is prepared by centrifuging fresh blood in an anticoagulant state, and harvesting the platelet-rich portion or condensing platelets. Studies have consistently demonstrated that PRP concentrates are an abundant source of growth factors, such as platelet-derived growth factor (PDGF), transforming growth factor β (TGF-β), insulin-like growth factor 1 (IGF-1), and epithelial growth factor (EGF). The complex mechanisms underlying spinal cord injury (SCI) diminish intrinsic repair and neuronal regeneration. Several studies have suggested that growth factor-promoted axonal regeneration can occur for an extended period after injury. More importantly, the delivery of exogenous growth factors contained in PRP, such as EGF, IGF-1, and TGF-β, has neurotrophic effects on central nervous system (CNS) injuries and neurodegenerative diseases. However, only a few studies have investigated the effects of PRP on CNS injuries or neurodegenerative diseases. According to our review of relevant literature, no study has investigated the effect of intrathecal (i.t.) PRP injection into the injured spinal cord and activation of intrinsic mechanisms. In the present study, we directly injected i.t. PRP into rat spinal cords and examined the effects of PRP on normal and injured spinal cords. In rats with normal spinal cords, PRP induced microglia and astrocyte activation and PDGF-B and ICAM-1 expression. In rats with SCIs, i.t. PRP enhanced the locomotor recovery and spared white matter, promoted angiogenesis and neuronal regeneration, and modulated blood vessel size. Furthermore, a sustained treatment (a bolus of PRP followed by a 1/3 dose of initial PRP concentration) exerted more favorable therapeutic effects than a single dose of PRP. Our findings suggest by i.t. PRP stimulate angiogenesis, enhancing neuronal regeneration after SCI in rats. Although PRP induces minor inflammation in normal and injured spinal cords, it has many advantages. It is an autologous, biocompatible, nontoxic material that does not result in a major immune response. In addition, based on its safety and ease of preparation, we hypothesize that PRP is a promising therapeutic agent for SCI.

Dengue is one of the neglected tropical diseases (NTDs) transmitted by Aedes mosquitoes and continues to spread globally. When mosquitoes are infected with dengue virus (DENV), virus-derived DNA (vDNA) is generated in mosquitoes, which subsequently contributes to their immune response. We traced the generation and presence of dengue virus type 2 (DENV-2) vDNA in experimentally infected cultured mosquito cells and Aedes mosquitoes, and notably, in wild mosquitoes collected in Burkina Faso. Detection of vDNA was achieved using a method incorporating loop-mediated isothermal amplification (LAMP), specifically, a LAMP-based vDNA detection method (vDNA-LAMP). The LAMP reaction, using primers targeting a segment of the NS5 region of DENV-2, detected vDNA from crude DNA extracted from experimentally infected cultured cells and Aedes mosquitoes. Detection revealed that the amount of DENV-2 vDNA generated in infected cells was relatively low; nevertheless, vDNA-LAMP enabled successful detection. The timing and quantity of vDNA generation in cultured cells were associated with the initial number of viral particles introduced during infection. Furthermore, vDNA-LAMP was applied to detect dengue virus vDNA in wild mosquitoes in dengue-endemic regions. This resulted in the successful detection of DENV-2 vDNA in field-collected mosquitoes, indicating that a proportion of wild mosquitoes in Burkina Faso harbored DENV-2 vDNA. Mapping these vDNA-positive mosquitoes allowed the identification of areas where infected mosquitoes and/or their progeny were likely present. These findings provide insights into the dynamics of DENV-2 vDNA in natural environments and underscore the potential of vDNA-LAMP as a tool for tracing vDNA in wild mosquitoes, which are responsible for transmitting viral infections.

Historically endemic to Sub-Saharan Africa and South America, yellow fever is absent from the Asia-Pacific region. Yellow fever virus (YFV) is mainly transmitted by the anthropophilic Aedes mosquitoes whose distribution encompasses a large belt of tropical and sub tropical regions. Increasing exchanges between Africa and Asia have caused imported YFV incidents in non-endemic areas, which are threatening Asia with a new viral emergence. Here, using experimental infections of field-collected mosquitoes, we show that Asian-Pacific Aedes mosquitoes are competent vectors for YFV. We observe that Aedes aegypti populations from Singapore, Taiwan, Thailand, and New Caledonia are capable of transmitting YFV 14 days after oral infections, with a number of viral particles excreted from saliva reaching up to 23,000 viral particles. These findings represent the most comprehensive assessment of vector competence and show that Ae. aegypti mosquitoes from the Asia-Pacific region are highly competent to YFV, corroborating that vector populations are seemingly not a brake to the emergence of yellow fever in the region. Yellow fever is absent from the Asia/Pacific region, despite presence of the mosquito vector. Here, the authors demonstrate that mosquitoes collected from field sites across the region are capable of transmitting yellow fever virus, indicating that vector competence is not a barrier to disease spread.

Dengue is a global health threat, with severe cases causing significant complications. Cytokines have been proposed as potential indicators of disease severity; however, the short plasma half-life and pre-analytical instability of free-form cytokines limit their clinical applicability. Exosome-encapsulated cytokines are protected by a lipid bilayer and may provide a more stable and integrated representation of host immune responses. In this cross-sectional study, we analyzed single time-point plasma samples collected from patients during clinical evaluation between July and December 2023, with most samples obtained during the acute phase (within 7 days post-symptom onset). Plasma exosomes were isolated from patients with mild dengue, dengue with warning signs (DFWS), severe dengue (SD), other febrile illnesses, and healthy controls (HCs). Exosome-associated cytokines were quantified using a multiplex panel assessing 15 cytokines. Across the five study groups, significant differences in plasma exosome cytokine levels were observed for interleukin (IL)-1β, IL-6, IL-10, IL-12, interferon-γ (IFN-γ), and tumor necrosis factor (TNF)-α (all p < 0.05). Post-hoc analyses further demonstrated that IL-6, IL-10, and TNF-α levels were significantly higher in both the DFWS and SD groups compared with HCs (all p < 0.01). In a subsequent analysis comparing mild dengue with the combined DFWS/SD group, significantly higher exosomal levels of IL-1β, IL-5, IL-10, IL-12, IL-13, and TNF-α were observed in the DFWS/SD group (all p < 0.05). Receiver operating characteristic (ROC) analysis showed that IL-1β, IL-10, and TNF-α moderately discriminated mild from severe cases, with area under the curve (AUC) values of approximately 0.7. An \"all-positive\" panel (TNF-α, IL-10, and IL-1β) achieved 84% sensitivity and 67.5% specificity for identifying DFWS/SD. These findings suggest that combined exosomal cytokine profiling may aid in disease severity stratification. However, given the cross-sectional design and moderate discriminatory performance, larger prospective studies are needed to validate its clinical applicability.