Biology subjects

Jia, L.

Publications and source records attributed to Jia, L..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Pheromone circuits and transcriptional cascades modulating transcriptional and chromatin states in the Drosophila central brain with social experience

Social experience significantly influences the behavioral and physiological responses of animals, including humans. In many animals, social isolation increases aggression, courtship, locomotion, and feeding while disrupting sleep. This occurs when peripheral neurons detect social signals, such as pheromones, which activate decision-making circuits in the brain. However, the molecular and circuit mechanisms of how chronic social isolation or enrichment alter gene expression and affect neuronal function and behavior remain unclear. In this study, we examined how transcription patterns and chromatin marks in male Drosophila brains change in response to social experience, and the effect of pheromone circuits and transcription factors involved in social circuit function. We focused on pheromone receptors Or47b and Or67d, as well as transcription factors FruM and DsxM. Our findings suggest that social experience affects multiple genes in the central brain. Disrupting Or47b, Or67d, FruM, and DsxM function moderated the transcriptional responses through antagonistic interactions. Specifically, Or47b circuits predominantly mediated transcriptional responses to social isolation through DsxM function, while Or67d and FruM regulated responses to group housing. Notably, mutants of fruM and dsxM exhibited more extensive transcriptional changes in the brain than Or mutants, especially for FruM/DsxM target genes. While social experience did not lead to detectable alterations in the overall chromatin profile in the whole brain, mutants of the four genes resulted in significant changes in the enrichment of H3K4me3 and RNA polymerase II (RNAPolII) compared to wild type. Furthermore, mutants in fruM and dsxM generally eliminated social experience-dependent changes in sleep and locomotion behaviors, whereas Or mutants exhibited more modest disruptions. Overall, our results uncover the pheromone circuits and transcriptional cascades in regulating molecular and behavioral responses to social experience.

neuroscience↗

bioRxiv2025

Social experience alters behaviors by reprogramming the Fruitless pathway and circadian state in Drosophila

From flies to humans, social experience affects various cognitive and behavioral processes. Previous studies have shown that group housing suppresses many behaviors like courtship, aggression, and feeding in Drosophila melanogaster, in addition to resetting the circadian state. Here, we focus on group housing-induced courtship suppression. To determine the mechanisms by which social experience modulates courtship behaviors, we performed bulk tissue RNAseq and single-cell RNAseq from cells expressing FruitlessM (FruM) and DoublesexM (DsxM), two transcription factors that label interconnected neural circuits for socially driven behaviors, from grouped or isolated male brains. These revealed that social isolation alters fru and dsx levels throughout the brain. Knocking down fruM in different fruM-positive neuron subpopulations in the brains has diverse effects on social experience-dependent changes in courtship. Furthermore, group housing increases the expression of stripe (sr) and Hormone receptor-like in 38 (Hr38) genes encoding neural activity-induced transcription factors in most neurons within social circuits. We found that knocking down sr in fruM-positive neurons effectively eliminates the impact of social experience by increasing courtship in group-housed males. Importantly, social experience also alters the expression of FruM/DsxM putative target genes regulating circadian states throughout the brain. Disrupting the function of multiple circadian genes diminishes the effect of group housing on courtship. Our findings suggest that group housing/social enrichment suppresses courtship by reprogramming the circadian arousal state, whereas courtship-elevating effects of social experience rely on unique influences of FruM expression and function in different neurons within social and clock circuits. These results are significant as they point to modulation of circadian arousal state as a possible central strategy for mediating the pleiotropic effects of social experience on organismal responses.

neuroscience↗

bioRxiv2025

Brain-wide cell-type-specific noradrenergic modulation of the transcriptome

Neuromodulatory systems such as the locus coeruleus-norepinephrine (LC-NE) system exert a widespread influence on brain function, yet the transcriptional consequences of such neuromodulatory perturbations remain largely unknown across the many unique cell types in the brain. In this study, we establish a generalizable framework to map brain-wide, cell-type-specific gene expression changes in mice following in vivo chemogenetic activation or inhibition of LC neurons. Single-nucleus RNA sequencing revealed that LC perturbation induces widespread but highly cell type- and region-specific transcriptional program changes, shaped by the distribution of adrenergic receptor subtypes. These findings support a model in which a shared global signal of neuromodulatory tone can produce discrete, context-dependent cellular outcomes through distinct molecular gating mechanisms of cell-type-specific adrenergic receptor subtype combinations. By establishing gene expression as a quantifiable metric of neuromodulatory control, this study lays the foundation for transcriptionally informed interventions capable of modulating brain functions with cellular precision.

neuroscience↗

bioRxiv2025

Splice-switching ASOs targeting an Alu-derived exon in the AURKA 5'UTR collapse an SRSF1-AURKA-MYC oncogenic circuit in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal malignancy, driven by oncogenic KRAS mutations and dysregulated oncogenes, such as SRSF1, MYC, and AURKA. Although KRAS-targeted therapies are in development, resistance mechanisms underscore the need to identify alternative vulnerabilities. Here, we uncover an SRSF1-AURKA-MYC oncogenic circuit, wherein SRSF1 regulates AURKA 5UTR alternative splicing, enhancing AURKA protein expression; AURKA positively regulates SRSF1 and MYC post-translationally, independently of its kinase activity; and MYC in turn transcriptionally upregulates both SRSF1 and AURKA. Elevated SRSF1 in tumor cells promotes inclusion of an exonized Alu exon in the AURKA 5UTR, resulting in splicing-dependent mRNA accumulation and exon-junction- complex deposition. Modulating 5UTR splicing with splice-switching antisense oligonucleotides (ASOs) collapses the oncogenic circuit, reducing PDAC cell viability and triggering apoptosis. Our findings identify AURKA alternative splicing as a critical regulatory node and highlight ASO-mediated splice-switching as a potential therapeutic strategy that simultaneously targets SRSF1, AURKA, and MYC oncogenes.

cancer biology↗

bioRxiv2025

Microbiota promote enhanced CD39 expression in γδ intraepithelial lymphocytes through the activation of TCR and IL-15 signaling

Intraepithelial lymphocytes expressing the {gamma}{delta} T cell receptor ({gamma}{delta} IEL) provide continuous surveillance of the intestinal epithelium. We report that mice harboring a microbiota-specific hyperproliferative {gamma}{delta} IEL ({gamma}{delta}HYP) phenotype also upregulate the expression of the ectonucleotidase CD39, a marker of regulatory {gamma}{delta} T cells. Enhanced TCR and IL-15 signaling correlates with a progression from a naive-like CD39neg {gamma}{delta} IEL to a more mature, tissue-adapted CD39hi IEL population. We found that TCR{gamma}{delta} activation drives CD122-mediated CD39 upregulation on {gamma}{delta}HYP IELs and increased mucosal IL-15 further amplifies CD39 expression in these cells. Further investigation revealed that CD39 induction requires sustained exposure to the {gamma}{delta}HYP-associated microbiota. Moreover, CD39hi {gamma}{delta} IELs exhibit a reduced capacity to produce pro-inflammatory cytokine, which may explain the lack of histopathology in {gamma}{delta}HYP mice. Overall, our study identifies a previously unappreciated mechanism by which an altered microbiota amplifies CD39 expression on {gamma}{delta}HYP IELs, leading to the expansion of {gamma}{delta} IELs with regulatory potential.

immunology↗

bioRxiv2025

Intense oocyte competition builds the female reproductive reserve in mice

During the process of ovariogenesis, more than two-thirds of germ cells are sacrificed to enhance the quality of the remaining oocytes. But the detail process of selection is not completely understood in mammals. Here, by creating a high resolution 4- dimensional ovariogenesis imaging system, we recorded the progress of oocyte fate determination in live mouse ovaries, and discovered an oocyte competition mechanism that determines the survival of oocytes. We found that dominant oocytes catch and absorb the cell debris from sacrificed oocytes to enrich their cytoplasm for survival. Single-cell sequencing demonstrated that this competition follows a classic autophagy- driven model. Blocking competition by suppressing autophagy resulted in an enlarged pool of survived oocytes. However, these oocytes lacking competition were unable to fully develop and contribute to fertility. Our study suggests that mammals have evolved a unique intensive competition system to enhance oocyte quality, necessary to support their long reproductive lifespan.

developmental biology↗

bioRxiv2025

Roles of spoVF operon subunits A and B in regulating cell morphology and biofilm formation in the biocontrol agent Bacillus subtilis

Enhanced expression of spoVF operon (sporulation initiation factor; dipicolinic acid (DPA) synthase) in Bacillus subtilis vegetative cells has been reported to increase host attachment and biocontrol ability. However, how the spoVF operon regulates these essential biocontrol factors remains unknown. In this study, it was found that the knockout of the spoVFA or spoVFB subunits, individually ({Delta}A and{Delta} B), or together ({Delta}A{Delta}B), decreased DPA biosynthesis, host attachment, nutrient competition ability, and biocontrol efficacy in B. subtilis. Moreover, the cell shape of the knockout strains changed from short rod to spherical. qRT-PCR analysis indicated that the spoVF operon regulates TCA cycle expression and biofilm formation by balancing the amounts of various transcriptional factors, such as spo0A, SinR, and AbrB, and the cofactor NADPH. The regulatory mechanism of the spoVF operon in B. subtilis biofilm-related genes was proposed for the first time. IMPORTANCEBacillus subtilis SpoVF operon contains the spoVFA or spoVFB subunits, which are responsible for the dipicolinic acid synthase activity. Dipicolinic acid is an important component of B. subtilis spores. In this study, the roles of spoVFA or spoVFB subunits in the biocontrol ability B. subtilis were examined, indicating that the spoVFA subunit plays a key role in B. subtilis biofilm formation, cell morphology, growth, and nutrient competition ability. Additionally, the regulatory network connecting the spoVF operon with biofilm formation-related genes of B. subtilis was proposed. The results obtained in this study help to understand key genes involved in the biocontrol ability of B. subtilis.

microbiology↗

bioRxiv2024

Ablation of sympathetic nerve-β3 adrenergic receptor-mediated adipose tissue lipolysis attenuates alcohol-induced liver injury in mice

BACKGROUND & AIMSBinge drinking causes fat accumulation in the liver and is a known risk factor for more severe forms of alcohol-associated liver disease (ALD). Although adipocyte-released free fatty acids (FFA) have been shown to contribute to alcohol-induced liver damage, the signaling pathways that trigger lipolytic activity in adipose tissues following acute alcohol overconsumption is largely unknown. Notably, activation of sympathetic nerve-{beta}3 adrenergic receptor (ADRB3) plays a central role in sustained adipocyte lipolysis. However, whether this pathway is involved in acute alcohol-induced lipolysis remains unclear. We aimed to explore the effect of the sympathetic nerve-ADRB3-mediated pathway on adipocyte lipolytic action and fatty liver development following acute alcohol exposure. METHODSC57BL/6J mice were administered a single binge of alcohol to model acute alcohol exposure. 6-hydroxydopamine (6-OHDA) was injected systemically or locally to ablate sympathetic nerves. Mice lacking Adrb3 selectively in fat tissues (Adrb3FKO) were generated. White adipose tissue lipolysis, fatty liver development, and liver damage were investigated. RESULTSA single alcohol binge in C57BL/6J mice led to significant increases in white adipose tissue (WAT) norepinephrine (NE) content and plasma FFA levels, accompanied by the development of alcoholic hepatic steatosis. Acute alcohol-induced adipose tissue lipolysis and ALD were significantly mitigated by 6-OHDA-mediated systemic and fat tissue specific sympathetic nerve ablation. Deletion of Adrb3 in adipocytes protected mice from acute alcohol-induced adipose tissue lipolysis, hepatic fat accumulation, and liver injury. CONCLUSIONOur data indicate that binge drinking leads to the development of fatty liver and liver damage by activating adipose tissue sympathetic nerve-ADRB3-mediated lipolysis in mice. SUMMARYBinge drinking causes hepatic steatosis and liver injury through the activation of sympathetic nerve-{beta}3 adrenergic receptor-stimulated white adipose tissue lipolysis and release of free fatty acids. O_FIG O_LINKSMALLFIG WIDTH=194 HEIGHT=200 SRC="FIGDIR/small/627372v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@12ec139org.highwire.dtl.DTLVardef@8fa283org.highwire.dtl.DTLVardef@1f65d50org.highwire.dtl.DTLVardef@168344c_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

Tumorigencity decrease in Bcl-xL deficient MDCK cells ensuring the safety for influenza vaccine production

Madin-Darby canine kidney (MDCK) cells are the recognized cell strain for influenza vaccine production. However, the tumorigenic potential of MDCK cells raises concerns about their use in biological product manufacturing. To reduce MDCK cells tumorigenicity and ensure the safety of influenza vaccine production, a B-cell lymphoma extra-large (Bcl-xL) gene, which plays a pivotal role in apoptosis regulation, was knocked-out in original MDCK cells by CRISPR-Cas9 gene editing technology, so that a homozygous MDCK-Bcl-xL-/- cell strain was acquired and named as BY-02. Compared with original MDCK cells, the proliferation and migration ability of BY-02 were significantly reduced, while apoptosis level was significantly increased, the endogenous mitochondrial apoptotic pathway were also modulated after Bcl-xL knock-out in MDCK cells. For tumor formation assays in nude mouse tests, all ten mice injected with original MDCK cells presented tumors growth in the injection site, in contrast to only one mouse injected with BY-02 cells presented tumors growth. These findings suggest that Bcl-xL knock-down is an effective strategy to inhibit tumor formation in MDCK cells, making BY-02 a promising genetically engineered cell strain for influenza vaccine production.

cell biology↗

bioRxiv2024

Long-Range Enhancer Networks Gradually Emerge as Key Regulators During Human Cortical Neurogenesis

The chromatin in the human brain cortex shows more enhancer-enhancer contacts than in macaques and mice, yet the organization of these contacts across cellular states and their mechanisms remain unclear. Here, we developed SCOPE-C, a cost-effective technique designed for mapping DNase I Hypersensitive Sites and their spatial interactions, with the potential for scalability to single-cell resolution. Employing SCOPE-C, we generated a comprehensive chromatin map detailing cis-regulatory elements in four cell types during neurogenesis in human, macaque, and mouse fetal cortex. This map introduces a model of long-range enhancer networks that regulate gene transcription during human cortical neurogenesis. In this model, CTCF-mediated loop extrusion forms stripes of enhancer interaction hubs extending up to 10 Mb in human Excitatory Neurons. Enriched with human-specific enhancers and neuropsychiatric disorder-linked SNPs, these remarkably long-range networks predominantly control EN marker genes, suggesting their critical role in robust gene expression during human cortical neurogenesis.

genomics↗

bioRxiv2024

Efficacy and mechanism of actions of cipargamin as an antibabesial drug candidate

Babesiosis is a disease brought on by intraerythrocytic parasites of the genus Babesia. Current chemotherapies are accompanied by side effects and parasite relapse. Therefore, it is crucial to develop highly effective drugs against Babesia. Cipargamin (CIP) has shown inhibition against apicomplexan parasites, mainly Plasmodium and Toxoplasma. This study evaluated the growth-inhibiting properties of CIP against Babesia spp. and investigated the mechanism of CIP on B. gibsoni. The half inhibitory concentration (IC50) values of CIP against the in vitro growth of B. bovis and B. gibsoni were 20.2 {+/-} 1.4 nM and 69.4 {+/-} 2.2 nM, respectively. CIP significantly inhibited the growth of B. microti and B. rodhaini in vivo. Resistance was conferred by L921V and L921I mutations in BgATP4, which reduced the sensitivity to CIP by 6.1- and 12.8-fold. The inhibitory potency of CIP against BgATP4-associated ATPase activity was moderately reduced in mutant strains, with a 1.3-fold and 2.4-fold decrease in BgATP4L921V and BgATP4L921I, respectively, compared to that of BgATP4WT. An in silico investigation revealed reductions in affinity for CIP binding to BgATP4L921V and BgATP4L921I compared to BgATP4WT. Resistant strains showed no significant cross-resistance to atovaquone (ATO) or tafenoquine succinate (TQ), with less than a onefold change in IC50 values. Combining CIP with TQ effectively eliminated B. microti infection in SCID mice with no relapse, and parasite DNA was not detected by qPCR within 90 days post-infection. Our findings reveal the efficacy of CIP as an anti-babesial agent, its limitations as a monotherapy due to resistance development, and the potential of combination therapy with TQ to overcome said resistance and achieve complete parasite clearance.

microbiology↗

bioRxiv2024

Acute BRCAness Induction and AR Signaling Blockage through CDK12/7/9 Degradation Enhances PARP Inhibitor Sensitivity in Prostate Cancer

Current treatments for advanced prostate cancer (PCa) primarily target the androgen receptor (AR) pathway. However, the emergence of castration-resistant prostate cancer (CRPC) and resistance to AR pathway inhibitors (APSIs) remains ongoing challenges. Here, we present BSJ-5-63, a novel proteolysis-targeting chimera (PROTAC) targeting cyclin-dependent kinases (CDKs) CDK12, CDK7, and CDK9, offering a multi-pronged approach to CRPC therapy. BSJ-5-63 degrades CDK12, diminishing BRCA1 and BRCA2 expression and inducing a sustained "BRCAness" state. This sensitizes cancer cells to PARP inhibitors (PARPis) regardless of their homologous recombination repair (HRR) status. Furthermore, CDK7 and CDK9 degradation attenuates AR signaling, enhancing its therapeutic efficacy. Preclinical studies, including both in vitro and in vivo CRPC models, demonstrate that BSJ-5-63 exerts potent anti-tumor activity in both AR-positive and AR-negative setting. This study introduces BSJ-5-63 as a promising therapeutic agent that addresses both DNA repair and AR signaling mechanisms, with potential benefits for a board patient population.

cancer biology↗

bioRxiv2024

Adaptive loss of shortwave cone opsins during genomic evolution in cartilaginous fish

There is ample evidence of the loss of the shortwave visual protein gene in cartilaginous fish. However, the underlying logic and mechanisms by which organisms need to adapt to the environment behind the opsin loss are still unclear. Here, we report the assembly structure of the whole genome of Okamejei kenojei and Prionace glauca, identify TcMar difference between skates/rays and sharks/chimaeras, and analyze the distribution characteristics and intra group differentiation of opsin-related genes in cartilaginous fish. By establishing a zebrafish model with short wave opsin gene deletion, we find blue or violet light via short-wave sensitive opsins SWS1 or SWS2 can cause the photoreceptor layer thinning (the biomarker for age-related macular degeneration in human eye) through enactive the cell aging. The loss of sws is helpful for alleviating the short-wave light damage on the eye. Since the tapetum lucidum in the eye is found broad existence in various cartilaginous fish, a logical hypothesis was creatively proposed that the existence of tapetum lucidum on the retina of cartilaginous fish is interdependent with the loss of shortwave visual protein gene, providing a new perspective and explanatory path for further understanding of the evolution of visual genes in cartilaginous fish.

bioinformatics↗

bioRxiv2024

Single particle cryo-electron microscopy with an enhanced 200 kV cryo-TEM configuration achieves near-atomic resolution

Single particle cryogenic electron microscopy (cryo-EM) as a structural biology methodology has become increasingly attractive and accessible to investigators in both academia and industry as this ever-advancing technology enables successful structural determination of a wide range of protein and nucleic acid targets. Although data for many high resolution cryo-EM structures are still obtained using a 300 kV cryogenic transmission electron microscope (cryo-TEM), a modern 200 kV cryo-TEM equipped with an advanced direct electron detector and energy filter is a cost-effective choice for most single particle applications, routinely achieving sub 3 angstrom ([A]) resolution. Here, we systematically evaluate performance of one such high-end configuration - a 200 kV Glacios microscope coupled with a Falcon 4 direct electron detector and Selectris energy filter (Glacios-F4-S). First, we evaluated data quality on the standard benchmarking sample, rabbit muscle aldolase, using three of the most frequently used cryo-EM data collection software: SerialEM, Leginon and EPU, and found that - despite sample heterogeneity - all final reconstructions yield same overall resolutions of 2.6 [A] and map quality when using either of the three software. Furthermore, comparison between Glacios-F4-S and a 300 kV cryo-TEM (Titan Krios with Falcon 4) revealed nominal resolution differences in overall reconstructions of a reconstituted human nucleosome core particle, achieving 2.8 and 2.5 [A], respectively. Finally, we performed comparative data analysis on the human RAD51 paralog complex, BCDX2, a four-protein complex of approximately 150 kilodaltons, and found that a small dataset ([≤]1,000 micrographs) was sufficient to generate a 3.3 [A] reconstruction, with sufficient detail to resolve co-bound ligands, AMP-PNP and Mg+2. In summary, this study provides evidence that the Glacios-F4-S operates equally well with all standard data collection software, and is sufficient to obtain high resolution structural information of novel macromolecular complexes, readily acquiring single particle data rivaling that of 300 kV cryo-TEMs.

biophysics↗

bioRxiv2024

Type I interferon induces TCR-dependent and -independent antimicrobial responses in γδ intraepithelial lymphocytes

Intraepithelial lymphocytes (IEL) expressing the {gamma}{delta} T cell receptor (TCR) survey the intestinal epithelium to limit the invasion of microbial pathogens. The production of type I interferon (IFN) is a central component of an antiviral immune response, yet how these pro-inflammatory cytokines contribute to {gamma}{delta} IEL effector function remains unclear. Based on the unique activation status of IELs, and their ability to bridge innate and adaptive immunity, we investigated the extent to which type I IFN signaling modulates {gamma}{delta} IEL function. Using an ex vivo culture model, we find that type I IFN alone is unable to drive IFN{gamma} production, yet low level TCR activation synergizes with type I IFN to induce IFN{gamma} production in murine {gamma}{delta} IELs. Further investigation into the underlying molecular mechanisms of co-stimulation revealed that TCR{gamma}{delta}-mediated activation of NFAT and JNK is required for type I IFN to promote IFN{gamma} expression in a STAT4- dependent manner. Whereas type I IFN rapidly upregulates antiviral gene expression independent of a basal TCR{gamma}{delta} signal, neither tonic TCR triggering nor the presence of a TCR agonist was sufficient to elicit type I IFN-induced IFN{gamma} production in vivo. However, bypassing proximal TCR signaling events synergized with IFNAR/STAT4 activation to induce {gamma}{delta} IEL IFN{gamma} production. These findings indicate that {gamma}{delta} IELs contribute to host defense in response to type I IFN by mounting a rapid antimicrobial response independent of TCR{gamma}{delta} signaling, and under permissive conditions, produce IFN{gamma} in a TCR-dependent manner.

immunology↗

bioRxiv2024

Regulation of Interstitial Lung Diseases by Pulmonary Endothelial Cells via PLVAP

Withdrawal statementThe authors have withdrawn this manuscript because the preliminary results require further experimental validation and more comprehensive data collection to ensure scientific rigor. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

cell biology↗

bioRxiv2024

Application of mechanistic multiparameter optimization and large scale in vitro to in vivo pharmacokinetics correlations to small molecule therapeutic projects

Computational chemistry and machine learning are used in drug discovery to predict target-specific and pharmacokinetic properties of molecules. Multiparameter optimization (MPO) functions are used to summarize multiple properties into a single score, aiding compound prioritization. However, over-reliance on subjective MPO functions risks reinforcing human bias. Mechanistic modeling approaches based on physiological relevance can be adapted to meet different potential key objectives of the project (e.g. minimizing dose, maximizing safety margins and/or minimized drug-drug interaction risk) while retaining the same underlying model structure. The current work incorporates recent approaches to predict in vivo PK properties and validates in vitro to in vivo correlation analysis to support mechanistic PK MPO. Examples of use and impact in small molecule drug discovery projects are provided. Overall, the mechanistic MPO identifies 83% of the compounds considered as short-listed for clinical experiments in the top 2nd percentile, and 100% in the top 10th percentile, resulting in an area under the receiver operating characteristic curve (AUCROC) > 0.95. In addition, the MPO score successfully recapitulates the chronological progression of the optimization process across different scaffolds. Finally, the MPO scores for compounds characterized in pharmacokinetics experiments are markedly higher compared to the rest of the compounds synthesized, highlighting the potential of this tool to reduce the reliance on in vivo testing for compound screening.

pharmacology and toxicology↗

bioRxiv2024

Determination and characterization of papillomaviurs and parvovirus causing mass mortality of Chinese tongue sole (Cynoglossus semilaevis) in China

Chinese tongue sole (Cynoglossus semilaevis) is one of the representative species in flatfish aquaculture in China. In recent years, massive mortality of farmed Chinese tongue soles occurred in Tianjin, China. The causative pathogens were determined as Cynoglossus semilaevis papillomavirus (CsPaV) and parvovirus (CsPV) by electron microscopy, virus isolation, experimental challenge, histopathological analysis, genome sequencing, fluorescence In situ hybridization (FISH) and epidemiology investigation. Electron microscopy showed large numbers of spherical non-enveloped virus particles presenting in liver, kidney, spleen, gill and heart of the diseased fish. The viruses were isolated and propagated in flounder gill cells (FG) and induced a typical cytopathic effect (CPE). The cumulative mortality reached 100% at 8 dpi by intraperitoneal injection. The complete genome of CsPaV and CsPV was 5939 bp and 3663 bp in size respectively, and both viral genomes shared no nucleotide sequence similarity with other viruses. The CsPaV contained seven predicated protein coding regions (E1, E2, L2, L1a, L1b, sORF1 and sORF2) and CsPV contained three predicated protein coding regions (NS1, VP and ORF3). Phylogenetic analysis basing on L1 and NS1 protein sequences revealed that CsPaV and CsPV are novel members belonging to new genus in Papillomaviridae and Parvoviridae family. FISH results showed positive signals in spleen and kidney tissues from CsPaV and CsPV infected fish and the two viruses could co-infected one cell. Epidemiological investigation showed that the two viruses cocurrented in 82.9% sampled fish and they were proved to be the pathogenic agents of the emerging disease in farmed Chinese tongue soles in China. This study represents the first report of co-infection of papillomavirus and parvovirus in farmed fish and provides a basis for further studies on prevention and treatment of the emerging viral disease, and also represents clues to elucidate the the mechanisms of viruses co-infection and evolution of viruses. Author summaryChinese tongue sole is a valuable fish kept in marincultures. Outbreak of an emerging disease caused massive mortality and resulted in significant economic loss. The pathogenic agent remains unknown. In this study, we identified papillomavirus (CsPaV) and parvovirus (CsPV) from the diseased fish simultaneously, and they are proved to be novel members belonging to new genus in Papillomaviridae and Parvoviridae family. It was shown that the emerging disease was caused by co-infection with the two viruses. Viral co-infections are widespread in nature, however, studies and available data on viral co-infections in fish aquaculture are limited. Our findings represent new clues to elucidate the mechanisms of viruses co-infection and evolution of viruses, and moreover, the present study provide a solution for the control of emerging viral diseases in Chinese tongue sole.

microbiology↗