Biology subjects

Castello-Sanjuan, M.

Publications and source records attributed to Castello-Sanjuan, M..

5 recordsLinked to original sources

bioRxiv2025

The pupal stage is a developmental window for RNA virus persistence in Drosophila

RNA viruses establish persistent infections in insects through mechanisms that are not fully understood. We focused on three positive-sense RNA viruses that naturally establish persistent infections: Drosophila A virus (DAV), Drosophila C virus (DCV), and Nora virus. We examined how these viruses interact with their hosts during development and we found that pupal metamorphosis is a critical window where virus-host immune interactions influence persistence differently across viruses. Peak viral loads and replication occur during pupation, coinciding with increased endogenous reverse transcriptase activity. Notably, reverse transcription of viral RNA genomes produces viral DNA (vDNA) forms of DAV and DCV that are first detectable during pupation and are involved in persistence. In contrast, Nora virus achieves persistence without detectable vDNA. Immune responses during pupation are virus-specific, involving suppression of RNA interference components and varied regulation of JAK-STAT signaling. After metamorphosis, DAV continues producing vDNA into adulthood while DCV shows transient vDNA production, and Nora virus bypasses vDNA production altogether. These findings point to pupation as a key developmental stage for the establishment of persistent infections through distinct viral persistence strategies.

microbiology↗

bioRxiv2025

Microbiome composition modulates the lethal outcome of Drosophila A virus infection

Host-associated microbiomes can strongly influence viral infection outcomes, yet how minor variations in commensal bacterial composition modulate viral pathogenesis remain poorly understood. Here, we used Drosophila melanogaster to investigate how bacterial microbiome composition affects pathogenesis of enteric RNA viruses. Lactiplantibacillus plantarum supplementation increased bacterial microbiome diversity without altering total bacterial load, while Acetobacter pomorum supplementation had minimal impact on the bacterial microbiome. L. plantarum-enriched flies exhibited an additional [~]15% reduction in lifespan from Drosophila A virus (DAV) infection despite showing reduced viral protein accumulation and similar viral RNA levels. The reduction in tolerance to viral infection required live bacteria and was observed only for DAV, as no change in mortality was observed with Nora virus or Drosophila C virus infections. Mechanistic investigations revealed that tolerance reduction occurs independently of transcriptional immune responses, as DAV-infected flies showed similar transcriptional profiles regardless of bacterial microbiome composition. Intestinal barrier function assays demonstrated that L. plantarum-supplemented flies died before developing signs of gut barrier disruption, suggesting that extra-intestinal mechanisms contribute to mortality; this interpretation is further supported by similar levels of intestinal damage markers observed in virus-infected flies under both microbiome conditions. Viral genomic sequencing ruled out microbiome-driven selection of more pathogenic viral variants, as no adaptive mutations were observed between microbiome conditions that could account for the differential pathogenesis. These findings describe how subtle shifts in microbiome composition modulate viral infection outcomes through pathways that operate independently of canonical immune responses, viral evolution, and intestinal damage.

microbiology↗

bioRxiv2025

Viral infections reduce Drosophila lifespan through accelerated aging

Do viral infections accelerate aging, and does this acceleration scale with pathogenicity? Using transcriptomic aging clocks, we measured biological age in Drosophila infected with four enteric RNA viruses spanning a broad pathogenicity range (i.e. reduction of host lifespan). All pathogenic infections accelerated aging and the magnitude of acceleration tracked pathogenicity. This pattern held across oral and systemic infection routes and was conserved in Caenorhabditis elegans where the non-pathogenic Orsay virus produced negligible aging acceleration. Pathway analysis indicated a systemic impact across aging hallmarks with virus- and tissue-specific signatures. Acceleration was comparable in females and males, but host context modulated the acceleration: the bacterial symbiont Wolbachia mitigated the virus-induced aging. Notably, biological age remained elevated even after viral clearance. These results demonstrate viruses act as age-distorters and link infection severity to lasting aging consequences, providing a quantitative framework for predicting long-term health effects of viral disease.

microbiology↗

bioRxiv2025

Persistent viral infections impact key biological traits in Drosophila melanogaster

Persistent viral infections have been assumed to impose minimal fitness costs for insects. We established persistent mono-infections of Drosophila melanogaster with four different enteric RNA viruses: Drosophila A virus (DAV), Drosophila C virus (DCV), Bloomfield virus, and Nora virus. We observed that these infections significantly reduce fly survival, alter the number of viable offspring per female, modulate microbiome composition, impact locomotor abilities, and change activity patterns. These results demonstrate the significant impact of persistent viral infections on key biological traits and expand our understanding of the fitness costs of persistent viral infections for the host. In addition, the four viruses displayed different accumulation kinetics and elicited unique transcriptional profiles with no common core responses. The transcriptional changes triggered by DCV infection persisted even after viral clearance. This comprehensive comparative dataset represents a valuable resource for researchers studying host-pathogen interactions, providing detailed transcriptional profiles, and behavioral measurements across different viral infections and time points. Our findings reveal that persistent viral infections modulate critical aspects of insect biology, affecting host physiology and behavior.

microbiology↗

bioRxiv2024

Limited impact of the siRNA pathway on transposable element expression in Aedes aegypti

Transposable elements (TEs) are DNA sequences that can change their position within a genome. In the germline of arthropods, post-transcriptional regulation of TE expression is mainly mediated by the Piwi-interacting RNA (piRNA) pathway. piRNAs are small RNAs of 24-30 nucleotides (nt) in length produced from genomic precursor transcripts as well as through a ping-pong amplification cycle. In somatic tissues, certain insects, such as Drosophila, instead rely on the small interfering RNA (siRNA) pathway as a key regulator of TE expression. siRNAs are 21nt small RNAs produced from double-stranded RNA by the endonuclease Dicer2, which guides an RNA-induced silencing complex to degrade a complementary RNA. However, whether the siRNA pathway also regulates TE expression in the mosquito Aedes aegypti, a medically significant vector species with abundant somatic piRNAs, is unknown. To address this question, we investigated the expression of TEs and small RNAs in both somatic and gonadal tissues of a Dicer2 mutant line of Ae. aegypti and its wild-type counterpart. Our results show a modified pattern of TE expression and a decrease in TE-derived 21nt small RNAs in the Dicer2 mutant, but no major shift of TE transcript abundance. The lack of a functional siRNA pathway also causes perturbations in piRNA ping-pong signatures and the expression of certain piRNA-associated genes, but without clear evidence for compensation by increased piRNA pathway activity. We conclude that the mosquito Ae. aegypti produces siRNAs targeting TEs but these lack a critical role in the regulation of TE expression both in somatic and in gonadal tissues.

genomics↗