Arthritogenic alphaviruses cause acute febrile illnesses associated with rash and arthritis when they are transmitted to humans through the bite of infected mosquitoes. Among these, chikungunya virus (CHIKV), transmitted primarily through the bite of infected Aedes aegypti and Aedes albopictus mosquitoes, causes explosive outbreaks involving hundreds of thousands to millions of cases, with recent re-emergence in several global regions. While several cellular receptors that mediate alphavirus entry into mammalian cells have been identified, their mosquito counterparts remained unknown, largely due to a lack of functional genomics tools for these invertebrate species. Here, we established a CRISPR-based genetic screening platform in Aedes albopictus cells and used it to identify Lachesin, a conserved invertebrate cell adhesion molecule, as a receptor for CHIKV and multiple related alphaviruses including Semliki Forest virus (SFV), o'nyong-nyong virus (ONNV), Mayaro virus (MAYV), and Ross River virus (RRV). Lachesin depletion using RNA interference, anti-Lachesin antibody treatment, and soluble forms of Lachesin blocked CHIKV and SFV E2-E1 glycoprotein-mediated infection of mosquito cells. We show that alphavirus E2-E1 glycoproteins bind the first immunoglobulin domain of Lachesin, facilitating attachment and internalization of virus-like particles. Orthologs from divergent mosquito genera, but not from arachnids or other arthropods, also serve as alphavirus receptors, suggesting that cellular receptor binding is not the main obstacle to arthritogenic alphavirus vector host expansion. Our findings enhance understanding of the mechanisms of alphavirus emergence and vector competence and could aid in the development of broadly active, entry-targeted therapeutics against multiple alphaviruses that threaten public health. ### Competing Interest Statement A provisional patent has been filed by some of the co-authors based on findings reported in the manuscript. National Institutes of Health, https://ror.org/01cwqze88, AI182377, T32AI700245, T32GM008313, T32GM144273, R24AI120942, P41GM132087 Burroughs Wellcome Fund Richard and Susan Smith Family Foundation G. Harold & Leila Y. Mathers Foundation International Human Frontier Science Program Organization, RGP011/2023

Study in fruit flies uncovers earliest known sign of impending muscle and fat wasting

Circulating hormones, that mediate communications across organs to maintain physiological balance, are commonly detected and quantified using enzyme-linked immunosorbent assays (ELISAs). However, whil...

Protein kinases orchestrate cellular processes through phosphorylation, yet the structural basis for their specific binding partner interactions remains largely unmapped. Here, we present a structure-...

Although bacterial genomes encode numerous potential toxins, it is unclear how evolution drives the specificity of these important virulence factors. Using an insect CRISPR screen, we identified the t...

Paraneoplastic syndromes arise when tumor-derived cytokines reprogram distant organs. Although mediators such as Interleukin-6 have been implicated, how these signals impair host organ function remain...

FlyBase lost a multimillion dollar grant when the Trump administration cut off Harvard’s federal funding in May. Now the repository is laying off staff — and researchers worldwide are worried.

PhD student Muhammad Ahmad has pinpointed important genes that regulate the retention and burning of fat in fruit flies and mammalian cells. His goal? To develop gene-editing therapies that could be a...

The layoffs jeopardize this resource, which has served more than 4,000 labs for about three decades.

Coenzyme A (CoA), derived from Vitamin B5 (VB5), is essential for lipid metabolism, energy production, and cell proliferation. While the intracellular functions of CoA are well characterized, its tiss...

G protein-coupled receptors (GPCRs) that couple to the Gαq signaling pathway control diverse physiological processes, yet the full complement of cellular regulators for this pathway remains unknown. H...

Understanding the evolution of insect resistance to natural and artificial poisons is important both to appreciate the adaptation of species to toxic ecological niches and manage pest insects. While r...

Genome-wide CRISPR screens map how genes support survival and contribute to diverse biological functions. Here, the authors use antiCRISPR to enhance genome-wide CRISPR screening in Drosophila and gen...

Secreted proteins regulate many aspects of animal biology and are attractive targets for biomarkers and therapeutics. However, comprehensively identifying the "secretome", along with their tissues of ...

Cystic Fibrosis (CF) is a monogenic genetic disease caused by mutations in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) chloride/bicarbonate channel, which is expressed in certain epithelia cells. Current therapies focus on restoring CFTR function but many gut-related pathologies persist, highlighting the need for complementary treatments to improve the quality of life of patients living with CF. In this study, we use Drosophila melanogaster as a model to investigate the gut-specific effects of Cftr loss. We demonstrate that enterocyte-specific knockdown of Cftr in flies recapitulates several CF pathologies, including reduced intestinal motility, nutrient malabsorption, and decreased energy stores. Using single-nuclei RNA sequencing (snRNA-seq), we identify significant transcriptional changes in the CF model gut, including the upregulation of acetylcholine esterase (Ace, human AChE), which leads to reduced cholinergic signaling. Cholinergic signaling has been shown to affect CFTR function but this is the first time CFTR loss of function has been shown to alter cholinergic signaling. Functional assays confirm that cholinergic sensitivity is diminished in CF guts and restoring cholinergic signaling via Ace knockdown rescues multiple CF-associated phenotypes. Furthermore, we identify the transcription factor Forkhead (Fkh), the Drosophila homolog of human FOXA1/FOXA2, which is known to be a positive regulator of Cftr in the intestine, as a positive regulator of Ace expression in CF guts. This study establishes the Drosophila gut as a powerful model to investigate CF pathogenesis, genetic modifiers, and identifies Ace and Fkh as genetic modifiers. This work also suggests that enhancing cholinergic signaling may represent a viable therapeutic strategy for gastrointestinal manifestations of CF. ### Competing Interest Statement The authors have declared no competing interest. NIDDK, 5F32DK130290-03 Cystic Fibrosis Foundation, https://ror.org/00ax59295, LANE21F0-00816F221

The Drosophila proventriculus is a bulb-shaped structure at the juncture of the foregut and the midgut, which plays important roles in ingestion, peritrophic membrane synthesis, and the immune respons...