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A new potential mosquito-borne virus: detection of Human-derived Jingmenvirus in several-species of mosquitoes from Yaoundé, Cameroon.

BACKGROUND: Tick-borne Jingmenviruses are becoming an increasing arbovirus concern due to the rising number of reported infections in humans and animals, as well as their wide geographic distribution. The involvement of other hematophagous arthropods as vectors of Jingmenviruses is still unknown. METHODS: Mosquitoes were sampled in two different biotopes in Cameroon (Yaoundé and Garoua) during the rainy and the dry seasons in 2022 and 2023. Metatranscriptomics Next Generation Sequencing was conducted using Illumina technology. Viral sequences detection revealed the presence of several contigs with high sequence identity to a human-derived Jingmenvirus (HdJV) previously discovered in plasma from an individual from Yaoundé, Cameroon. A draft viral genome was constituted for each Jingmenvirus-positive samples. Maximum likelihood phylogenetic reconstructions were used to position mosquito-associated viruses within the diversity of Jingmenviruses. Statistical analyses were conducted to estimate the prevalence of infected mosquitoes and the effect of different variables (region, season, year, mosquito species) on Jingmenvirus detection. RESULTS: HdJV was identified during the dry and the rainy seasons in 4 species of mosquitoes: Aedes albopictus, Culex quinquefasciatus and Culex wansoni from Yaoundé, and Anopheles gambiae s.l. from Garoua. The overall prevalence of HdJV-infected mosquitoes was estimated to 0.90% [0.41-1.69]; and the unique variable significantly associated with HdJV detection was the sampling area: Yaoundé showed the highest prevalence (2.29% [0.95-4.68]) compared to Garoua (0.18% [0.01-0.79]). Mosquito-associated Jingmenviruses shared a high nucleotide identity (between 98.64-100% according to the segment) and clustered in the same clade in the phylogenetic analysis, that they belong to the same viral species circulating in different mosquito species. The viral genome shared between 96.4% and 98.9% nucleotide identity with a HdJV detected in the plasma of a patient suffering from febrile illness originating from the same area, suggesting the possible involvement of mosquitoes as vectors of arboviral Jingmenviruses in human infections. CONCLUSIONS: This finding provides new insights into the ecology and transmission dynamics of Jingmenviruses, highlighting mosquitoes as potential vectors, alongside ticks, in the zoonotic transmission of this virus group.

Jingmenvirus

Infection rate of Aedes aegypti mosquitoes with dengue virus depends on the interaction between temperature and mosquito genotype.

Dengue fever is the most prevalent arthropod-transmitted viral disease worldwide, with endemic transmission restricted to tropical and subtropical regions of different temperature profiles. Temperature is epidemiologically relevant because it affects dengue infection rates in Aedes aegypti mosquitoes, the major vector of the dengue virus (DENV). Aedes aegypti populations are also known to vary in competence for different DENV genotypes. We assessed the effects of mosquito and virus genotype on DENV infection in the context of temperature by challenging Ae. aegypti from two locations in Vietnam, which differ in temperature regimes, with two isolates of DENV-2 collected from the same two localities, followed by incubation at 25, 27 or 32°C for 10 days. Genotyping of the mosquito populations and virus isolates confirmed that each group was genetically distinct. Extrinsic incubation temperature (EIT) and DENV-2 genotype had a direct effect on the infection rate, consistent with previous studies. However, our results show that the EIT impacts the infection rate differently in each mosquito population, indicating a genotype by environment interaction. These results suggest that the magnitude of DENV epidemics may not only depend on the virus and mosquito genotypes present, but also on how they interact with local temperature. This information should be considered when estimating vector competence of local and introduced mosquito populations during disease risk evaluation.

Aedes

Metaviromic profiling of mosquito excreta using superhydrophobic collection devices expands the known RNA virome of North America.

Nearly 30% of emerging infectious disease events worldwide are transmitted by arthropod vectors, and this proportion continues to rise. Rapid and accurate detection is critical for directing vector control interventions, thereby reducing the likelihood of widespread transmission. Surveillance of infected mosquitoes can provide an early warning of impending human infection; however, conventional virus testing relies on processing large pools of mosquitoes and requires labor-intensive pre-processing. During rapidly developing epidemic or panzootic events, these delays may limit the effectiveness of public health responses. Mosquito excreta has recently emerged as a promising alternative substrate for pathogen detection. Sugar-fed mosquitoes regularly excrete gut contents, offering a rich source of nucleic acids. In this study, we developed and applied custom superhydrophobic excreta-collection funnels that efficiently aggregate excreta produced by field-collected Culex mosquitoes into attached microcentrifuge tubes. Shotgun metagenomic sequencing of this material revealed a diverse RNA virome, including both globally distributed viruses and those reported here for the first time from the Americas. Beyond virus detection, additional analyses enabled confirmation of host mosquito species and identification of trypanosomatid parasites, demonstrating the broader utility of mosquito excreta for integrated surveillance. We anticipate that methods and devices of this type will become valuable components of vector surveillance programs, particularly in remote or resource-limited settings where repeated collections are challenging. Overall, our findings highlight the potential of excreta-based monitoring to improve early detection of emerging or unknown pathogens of One Health importance, refine our understanding of mosquito virome biogeography, and facilitate the discovery of previously undescribed viruses.IMPORTANCEMany infectious diseases that affect people and animals are spread by mosquitoes and other biting insects, and the number of these outbreaks is increasing. Detecting pathogens in mosquito populations early can provide a critical warning before human cases begin, allowing health officials to act quickly. However, traditional surveillance requires collecting and processing large numbers of mosquitoes, which can be slow and labor-intensive during fast-moving outbreaks. Here we demonstrate a simpler approach: testing mosquito waste. When mosquitoes feed on sugar, they excrete material that contains genetic traces of viruses and other organisms. Using specially designed collection devices and modern genetic sequencing, we show that mosquito excreta can reveal a wide range of viruses and parasites while also identifying the mosquito species present. This method could make disease surveillance faster and more practical in remote or resource-limited settings, improving our ability to detect emerging pathogens that threaten human, animal, and environmental health.

Animals

A single-nucleus transcriptomic atlas of the adult Aedes aegypti mosquito.

The female Aedes aegypti mosquito's remarkable ability to hunt humans and transmit pathogens relies on her unique biology. Here, we present the Aedes aegypti Mosquito Cell Atlas, a comprehensive single-nucleus RNA sequencing dataset of more than 367,000 nuclei from 19 dissected tissues of adult female and male Aedes aegypti, providing cellular-level resolution of mosquito biology. We identify novel cell types and expand our understanding of sensory neuron organization of chemoreceptors to all sensory tissues. Our analysis uncovers male-specific cells and sexually dimorphic gene expression in the antenna and brain. In female mosquitoes, we find that glial cells in the brain, rather than neurons, undergo the most extensive transcriptional changes following blood feeding. Our findings provide insights into the cellular basis of mosquito behavior and sexual dimorphism. The Aedes aegypti Mosquito Cell Atlas resource enables systematic investigation of cell type-specific expression across all mosquito tissues.

Aedes aegypti

Hemolymph of Anopheles stephensi from noninfected and Plasmodium berghei-infected mosquitoes. 1. Collection procedure and physical characteristics.

Hemolymph was collected from adult female Anopheles stephensi by centrifugation of incised mosquitoes. Approximately 0.1 muliter was collected from each recently emerged mosquito, although smaller amounts were recovered with increasing age of the mosquito. Determinations were made of the pH, osmotic pressure, and specific gravity of this hemolymph at various times during the life of the adult mosquito. The values obtained were within the ranges found for other insects. Hemolymph collected from mosquitoes fed on hamsters infected with Plasmodium berghei had different values than hemolymph from mosquitoes fed on noninfected hamsters. This probably was due to differences between the quality of these 2 types of blood meals, rather than to the direct effects of the malaria parasite on the infected mosquito itself.

Aging

Autodissemination stations suppress Aedes notoscriptus mosquitoes and reduce Buruli ulcer risk in urban Australia: a randomized controlled field trial.

Aedes notoscriptus are mosquito vectors implicated in transmission of Mycobacterium ulcerans. This bacterium causes a destructive infection of skin and soft tissue called Buruli ulcer. Here we ran a randomized controlled trial in an urban Buruli ulcer endemic area in Melbourne, Australia to test whether autodissemination mosquito control stations, containing pyriproxyfen (larvicide) and Beauveria bassiana (entomopathogenic fungus), suppress Ae. notoscriptus populations. Six geographic areas each received 100 autodissemination stations for 8 weeks, and six control areas received no stations between 25 January 2024 and 21 March 2024. The primary outcome measure was mosquito population numbers. After the trial, there was a 70% average reduction in mosquito egg counts among the six intervention areas compared to control areas (P = 0.0076). In an ad hoc analysis, we then explored human Buruli ulcer notifications in treatment and control areas. After accounting for the 4.8-month mean incubation period, there was an 83% reduction in infection likelihood coinciding with peak intervention effect (intervention zones 1 case, control zones 6 cases, incidence ratio rate 0.167, 95% CI 0.0026-1.054, P = 0.047). The effect was not observed during the same time period in the year previous or following 2024, when no interventions were undertaken. A strong correlation (R2 = 0.85) was observed between decreased disease risk and mosquito suppression. These data show that autodissemination traps can effectively lower urban mosquito populations and reduce the threat of Buruli ulcer in humans.

Animals

Protocol for Detecting and Sequencing Chikungunya Virus from Field-Collected Mosquitoes.

Arboviral diseases represent a major public health challenge, especially in tropical regions where environmental conditions may favor the proliferation and spread of mosquito vectors. Thus, early and accurate detection of chikungunya virus (CHIKV) in mosquito populations can be a valuable tool for effective surveillance of circulating variants and for identifying new viral introductions. Given the challenges of detecting arboviruses in field-captured mosquitoes, we describe an integrated workflow for CHIKV molecular detection and whole-genome sequencing. This protocol includes mosquito homogenization using a bead-based mechanical disruptor, RNA extraction using TRIzol reagent with minor modifications, molecular screening using CHIKV-specific RT-qPCR, and whole-genome amplification followed by sequencing on Illumina platforms. Despite the protocol being optimized for individual mosquitoes, it results in high-quality RNA suitable for both entomological surveillance and genomic analysis. As this protocol allows recovery of complete CHIKV genomes from mosquito specimens, it can serve as a basis for genomic epidemiology studies, enabling monitoring of viral diversity and lineage dynamics, and facilitating early detection of emerging variants to support timely and targeted public health interventions in endemic and at-risk regions.

Animals

The impact of metagenomic interplay on the mosquito redox homeostasis.

Mosquitoes are exposed to oxidative challenges throughout their life cycle. The primary challenge comes from a blood meal. The blood digestion turns the midgut into an oxidative environment, which imposes pressure not only on mosquito fecundity and other physiological traits but also on the microbiota in the midgut. During evolution, mosquitoes have developed numerous oxidative defense mechanisms to maintain redox homeostasis in the midgut. In addition to antioxidants, SOD, catalase, and glutathione system, sufficient supply of the reducing agent, NADPH, is vital for a successful defense against oxidative stress. Increasing evidence indicates that in response to oxidative stress, cells reconfigure metabolic pathways to increase the generation of NADPH through NADP-reducing networks including the pentose phosphate pathway and others. The microbial homeostasis is critical for the functional contributions to various host phenotypes. The symbiotic microbiota is regulated largely by the Duox-ROS pathway in Drosophila. In mosquitoes, Duox-ROS pathway, heme-mediated signaling, antimicrobial peptide production and C-type lectins work in concert to maintain the dynamic microbial community in the midgut. Microbial mechanisms against oxidative stress in this context are not well understood. Emerging evidence that microbial metabolites trigger host oxidative response warrants further study on the metagenomic interplay in an oxidative environment like mosquito gut ecosystem. Besides the classical Drosophila model, hematophagous insects like mosquitoes provide an alternative model system to study redox homeostasis in a symbiotic metagenomic context.

Animals

California encephalitis virus transmission by arctic and domestic mosquitoes.

A zero passage arctic mosquito isolate of California encephalitis (CE) virus (showshoe hare subtype) was transmitted by wild-caught Aedes communis mosquitoes after 13 days incubation at 13 degrees and 23 degrees C, AFTER 20 days incubation at 13 degrees C, when mosquitoes imbibed 1 mouse LD50 in a blood meal. Transmission occurred after 20 days incubation at 13 degrees and 23 degrees C when mosquitoes were injected intrathoracially with 1 or 0.1 mouse LD50. Virus was also transmitted by A. aegypti 13 days after infection with 100 mouse LD50 by feeding or intrathoracic injection, and incubation at 13 degrees C. Virus antigen was detected in salivary glands of 42 percent virus-positive A communis mosquitoes by direct immunofluorescence, and in 50 percent or less of A aegypti mosquitoes by immunoperoxidase and immunofluorescence, with somewhat greater regularity by the indirect than the direct technique.

Aedes

Mosquitoes provide a transmission route between possums and humans for Buruli ulcer in southeastern Australia.

Buruli ulcer, a chronic subcutaneous infection caused by Mycobacterium ulcerans, is increasing in prevalence in southeastern Australia. Possums are a local wildlife reservoir for M. ulcerans and, although mosquitoes have been implicated in transmission, it remains unclear how humans acquire infection. We conducted extensive field survey analyses of M. ulcerans prevalence among mosquitoes in the Mornington Peninsula region of southeastern Australia. PCR screening of trapped mosquitoes revealed a significant association between M. ulcerans and Aedes notoscriptus. Spatial scanning statistics revealed overlap between clusters of M. ulcerans-positive Ae. notoscriptus, M. ulcerans-positive possum excreta and Buruli ulcer cases, and metabarcoding analyses showed individual mosquitoes had fed on humans and possums. Bacterial genomic analysis confirmed shared single-nucleotide-polymorphism profiles for M. ulcerans detected in mosquitoes, possum excreta and humans. These findings indicate Ae. notoscriptus probably transmit M. ulcerans in southeastern Australia and highlight mosquito control as a Buruli ulcer prevention measure.

Animals