Biology subjects

Fu, Y.

Publications and source records attributed to Fu, Y..

At least 145 records · Page 8Linked to original sources

bioRxiv2024

Heterogeneity in chromatin structure drives core regulatory pathways in B-cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric malignancy. Based on gene expression profiling, B-ALL can be classified into distinct transcriptional subtypes with differing disease outcomes. Many of these transcriptional subtypes are defined by mutations in transcription factors and chromatin-modifying enzymes, but how such diverse mutations lead to distinct transcriptional subtypes remains unclear. To illuminate the chromatin regulatory landscape in B-ALL, we analyzed 3D genome organization, open chromatin, and gene expression in 53 primary patient samples. At the level of 3D genome organization, we identified chromatin interactions that vary across transcriptional subtypes. These sites of variable 3D chromatin interactions correlate with local gene expression changes and are enriched for core drivers of B-ALL observed in genome-wide CRISPR knock-out screens. Sites of variable 3D genome interactions are frequently shared across multiple transcriptional subtypes and are enriched for open chromatin sites found in normal B-cell development but repressed in mature B-cells. Within an individual patient sample, the chromatin landscape can resemble progenitor chromatin states at some loci and mature B-cell chromatin at others, suggesting that the chromatin in B-ALL patient tumor cells is in a partially arrested immature state. By analyzing transcriptomic data from large cohorts of B-ALL patients, we identify gene expression programs that are shared across transcriptional subtypes, associated with B-cell developmental stages, and predictive of patient survival. In combination, these results show that the 3D genome organization of B-ALL reflects B-cell developmental stages and helps illustrate how B-cell developmental arrest interacts with transcriptional subtypes to drive B-ALL.

cancer biology↗

bioRxiv2024

Inkjet-printed graphene multielectrode arrays: an accessible platform for in vitro cardiac electrophysiology

In vitro models have now become a realistic alternative to animal models for cardiotoxicity assessment. However, the cost and expertise required to implement in vitro electrophysiology systems to study cardiac cells poses a strong obstacle to their widespread use. This study presents a novel, cost-effective approach for in vitro cardiac electrophysiology using fully-printed graphene-based microelectrode arrays (pGMEAs) coupled with an open-source signal acquisition system. We characterized the pGMEAs electrical properties and biocompatibility, observing low impedance values and cell viability. We demonstrated the platforms capability to record spontaneous electrophysiological activity from HL-1 cell cultures, and we monitored and quantified their responses to chemical stimulation with noradrenaline. This study demonstrates the feasibility of producing fully-printed, graphene-based devices for in vitro electrophysiology. The accessible and versatile platform we present here represents a step further in the development of alternative methods for cardiac safety screening.

bioengineering↗

bioRxiv2024

Coat protein of TCV suppresses RNA decay via ubiquitination and autophagy pathways to facilitate viral infection

Highlight statementThe findings highlight that TCV manipulates 26S proteasome and autophagy pathways to obstruct antiviral RNA decay defenses and ultimately enhance its ability to infect host cells. RNA decay is a pervasive process in eukaryotic cells. Viruses utilize the host cells intracellular machinery to gain access to essential molecules and subcellular structures required for infection during the pathogenesis process. The study demonstrates that turnip crinkle virus (TCV) infection enhances the expression of Arabidopsis Dcp1 (AtDcp1), which negatively regulates the accumulation of TCV RNA, indicating its involvement in antiviral defense. Nevertheless, TCV circumvents the antiviral defense based on RNA decay, as indicated by the capsid protein (CP) of TCV stabilizing the known nonsense-mediated RNA decay targeted transcripts. In vivo, CP physically interacts with AtDcp1, promoting AtDcp1 degradation via ubiquitination and autophagy pathways. This is evidenced by the observation that the degradation is inhibited by both 26S proteasome and autophagy inhibitors. Furthermore, CP elevates the polyubiquitination of Dcp1-Flag and the quantity of pre-autophagosome or autophagosome structures. These data indicate that CP suppresses RNA decay by interacting with AtDcp1 and mediating its degradation through the 26S proteasome and autophagy pathways, effectively subduing antiviral RNA decay. This study uncovers a previously unidentified virulence strategy in the ongoing conflict between plants and viruses.

pathology↗

bioRxiv2024

CHCHD2 mutant mice display mitochondrial protein accumulation and disrupted energy metabolism

Mutations in the mitochondrial cristae protein CHCHD2 lead to a late-onset autosomal dominant form of Parkinsons disease (PD) which closely resembles idiopathic PD, providing the opportunity to gain new insights into the mechanisms of mitochondrial dysfunction contributing to PD. To begin to address this, we used CRISPR genome-editing to generate CHCHD2 T61I point mutant mice. CHCHD2 T61I mice had normal viability, and had only subtle motor deficits with no signs of premature dopaminergic (DA) neuron degeneration. Nonetheless, CHCHD2 T61I mice exhibited robust molecular changes in the brain including increased CHCHD2 insolubility, accumulation of CHCHD2 protein preferentially in the substantia nigra (SN), and elevated levels of -synuclein. Metabolic analyses revealed an increase in glucose metabolism through glycolysis relative to the TCA cycle with increased respiratory exchange ratio, and immune-electron microscopy revelated disrupted mitochondria in DA neurons. Moreover, spatial genomics revealed decreased expression of mitochondrial complex I and III respiratory chain proteins, while proteomics revealed increased respiratory chain and other mitochondrial protein-protein interactions. As such, the CHCHD2 T61I point-mutation mice exhibit robust mitochondrial disruption and a consequent metabolic shift towards glycolysis. These findings thus establish CHCHD2 T61I mice as a new model for mitochondrial-based PD, and implicate disrupted respiratory chain function as a likely causative driver.

neuroscience↗

bioRxiv2024

High-throughput Image-based Clustering of CAR-T/Tumor Cocultures for Rapid and Facile Hit Identification

AO_SCPLOWBSTRACTC_SCPLOWChimeric antigen receptor T cell is important because of its potential to treat various diseases. As deep learning continues to advance, using unsupervised methods to classify medical images has become a significant focus because collecting high-quality labeled data for medical images is labor-intensive and time-consuming. Beyond the need for accurate labeling, there is a desire to explore the underlying characteristics of the data, even when labels may be ambiguous or uncertain. To address these challenges, we present a novel approach that combines image clustering with an insightful explanation of how these clusters are formed. Our method employs a U-net combined with a clustering algorithm to segment the dataset into different groups. After clustering, we use various techniques to interpret and elucidate the results. Moreover, our paper introduces a unique dataset focused on cell data, specifically highlighting the developmental patterns of cancer cells and T cells under various experimental conditions. This dataset offers a rich source of information and presents a complex challenge for image classification due to the diversity of conditions and cell behaviors involved. Our study thoroughly compares different architectural models on this new dataset, demonstrating the superior performance of our proposed architecture. Through experimental analysis and ablation studies, we provide substantial evidence of the benefits offered by our architecture, not only in terms of accuracy but also in its ability to reveal deeper insights into the data. This work advances the field of image classification and opens new possibilities for understanding complex biological processes through computer vision.

cell biology↗

bioRxiv2024

DeepSME: De Novo Nanopore Basecalling of Motif-insensitive DNA Methylation and Alignment-free Digital Information Decryptions at Single-Molecule Level

Hidden messages in DNA molecules by employing chemical modifications has been suggested for private data storage and transmission at high information density. However, rapidly decoding these "molecular keys" with corresponding basecallers remains challenging. We present DeepSME, a nanopore sequencing and deep-learning based framework towards single-molecule encryption, demonstrated by using 5-hydroxymethylcytosine (5hmC) substitution for individual nucleotide recognition rather than sequential interactions. This non-natural, motif-insensitive methylation disrupts ion current, resulting in a readout failure of 67.2%-100%, concealing the privacy within the DNAs. We further develop an alignment-free DeepSME basecaller as a key to reconstitute the digital information. Our three-stage training pipeline, expands k-mer size from 46 to 49, achieving over 92% precision and recall from scratch. DeepSME deciphers fully 5hmC concealed text and image within 16x coverage depth with an F1-score of 86.4%, surpassing all the state-of-the-art basecallers. Demonstrated on edge computing devices, DeepSME holds supreme potential for DNA-based private communications and broader bioengineering and medical applications.

bioinformatics↗

bioRxiv2024

Multi-strategies embedded framework for neoantigen vaccine maturation

Effective cancer immunotherapy hinges on the precise recognition of neoantigens, presented as binary complexes with major histocompatibility complex (MHC) molecules, by T cell receptors (TCR). The development of immunogenic peptide predictors and generators plays a central role in personalizing immunotherapies while reducing experimental costs. However, the current methods often fall short in leveraging structural data efficiently and providing comprehensive guidance for neoantigen selection. To address these limitations, we introduce NEOM, a novel neoantigen maturation framework encompassing five distinct modules: "policy", "structure", "evaluation", "selection" and "filter". This framework is designed to enhance precision, interpretability, customizability and cost-effectiveness in neoantigen screening. We evaluated NEOM using a set of random synthetic peptides, followed by available clinically-derived peptides. NEOM achieved higher performance on generated peptide quality compared to other baseline models. Using established predictors for filtering revealed a substantial number of peptides with immunogenic potential. Subsequently, a more rigorous binding affinity evaluation using free energy perturbation methods identified 6 out of 38 candidates showing superior binding characteristics. MHC tetramer peptide exchange assays and flow cytometry experiments further validate five of them. These results demonstrate that NEOM not only excels in identifying diverse peptides with enhanced binding stability and affinity for MHC molecules but also augments their immunogenic potential, showcasing its utility in advancing personalized immunotherapies.

bioinformatics↗

bioRxiv2024

Host-derived Lactobacillus plantarum alleviates hyperuricemia by improving gut microbial community and hydrolase-mediated degradation of purine nucleosides

AbstractGut microbiota has been considered to be associated with the development of hyperuricemia (HUA) and gout. Some prebiotics from different sources had the potential alleviation function in HUA. However, whether host-derived potential probiotics, like Lactobacillus, from the gut of HUA animals could prevent the development of HUA is still uncertain. In this study, we established a HUA geese model and isolated a Lactobacillus plantarum strain, SQ001, from the cecum of HUA geese. Nucleoside co-culture and metabolomics analyses revealed that L. plantarum SQ001 is involved in the absorption and hydrolysis of nucleosides. Whole genome analysis showed there are four genes related with nucleosides hydrolysis in L. plantarum SQ001. The function of iunH, a nucleoside hydrolase gene, was further confirmed by heterologous expression and knockout assays. Oral administration of L. plantarum SQ001 in HUA geese models upregulated the Lactobacillus abundance and reduced serum uric acid (UA) levels. Likewise, in mouse models, L. plantarum SQ001 increased the L. plantarum abundance and lowered serum UA levels by reducing hepatic UA synthesis protein XO and renal UA reabsorption protein GLUT9 expression, while increasing renal UA excretion protein ABCG2 expression. Our findings demonstrated that host-derived probiotics from geese could alleviate gut microbe dysbiosis and HUA in its host and mouse model. This study provides insights into the potential probiotic role of Lactobacillus plantarum in HUA or gout therapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/606206v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@698e7eorg.highwire.dtl.DTLVardef@a2091org.highwire.dtl.DTLVardef@e0348aorg.highwire.dtl.DTLVardef@19958ad_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

CUT&Tag for high-resolution epigenomic profiling from a low amount of Arabidopsis tissue

BackgroundThe genome-wide profiling of chromatin states that are defined by different histone post-translational modifications, known as epigenomic profiling, is crucial for understanding the epigenetic regulations of gene expression, both in animal and plant systems. CUT&Tag (Cleavage Under Targets and Tagmentation, [1]) is a novel enzyme-tethering method for epigenomic profiling, initially developed for mammalian cells. CUT&Tag has several advantages compared to the most commonly used epigenomic profiling methods such as Chromatin Immunoprecipitation followed by high-throughput sequencing (ChIP-seq). CUT&Tag allows epigenenomic profiling from a much less amount of starting material compared to ChIP-seq. CUT&Tag is based on the in situ cleavage of DNA by enzymes tethered to antibodies, while in ChIP-seq, the cleavage is done by a nearly random fragmentation step. In theory, this difference in the way of cleaving DNA allows CUT&Tag to reach a higher resolution compared to ChIP-seq. Therefore, CUT&Tag holds the potential to profile the genome-wide distribution at a high resolution even from a small amount of plant tissues. ResultsWe profiled the genome-wide distribution of three histone modifications, H3K27me3, H3K4me3 and H3K27Ac, from a few seedlings of Arabidopsis that weighed around 0.01 grams. By comparing the H3K27me3 profiles generated from ChIP-seq and CUT&Tag, we showed that CUT&Tag and ChIP-seq capture the same broad lines of the epigenomes, but they also revealed different sets of peaks. Analysis using the CUT&Tag datasets for the three histone modifications revealed their genomic locations and their relationship with the gene expression level, which are consistent with the expected effect of these histone marks on gene transcription. By comparing to the nucleosome occupancy data, we show that CUT&Tag reached nucleosomal resolution, a much higher resolution than ChIP-seq. In the end, we presented that the increased resolution of CUT&Tag could better reveal the exon enrichment of histone modifications and the epigenetic states of the +1 nucleosome, showing benefits and advantages that this technique could bring to the field of plant epigenetics and chromatin study in general. ConclusionCUT&Tag is a valid, easy-to-perform, cost-effective, and reliable approach for efficient epigenomic profiling in Arabidopsis, even with limited amount of starting material and provides a higher resolution compared to ChIP-seq. Because the CUT&Tag protocol starting input is isolated nuclei, it is also applicable to other model and non-model plants.

plant biology↗

bioRxiv2024

Single influenza A viruses induce nanoscale cellular reprogramming at the virus-cell interface

Viruses, as nanoscale entities with limited proteomes, must efficiently infect target cells using their available resources. During infection, individual virions induce specific cellular signaling within the virus-cell interface, a nanoscale patch of the plasma membrane in contact with the virus. However, virus-induced receptor recruitment and cellular activation are transient processes that occur within minutes and at the nanoscale level. Hence, the temporal and spatial kinetics of such early events often remain poorly understood due to technical limitations. To address this challenge, we developed a novel protocol to covalently immobilize unmodified influenza A viruses on glass surfaces before exposing them to live epithelial cells. This approach extends the observation time for virus-plasma membrane interaction while preserving the viruses native state for uncompromised cell interaction. Using single-molecule super-resolution microscopy, we investigated virus-receptor interaction showing that viral receptors are not immobilized by the virus but rather slowed down, which leads to a specific local receptor accumulation and turnover. We further followed the dynamics of clathrin-mediated endocytosis at the single-virus level and demonstrate the recruitment of adaptor protein 2 (AP-2), previously thought to be uninvolved in influenza A virus infection. Finally, we examined the nanoscale organization of the actin cytoskeleton at the virus-binding site, showing a local and dynamic response of the cellular actin cortex to the infecting virus. Our findings provide novel insights into the fundamental process of virus-cell interaction and demonstrate the versatility and potential impact of our approach on virus-cell biology.

microbiology↗

bioRxiv2024

MJF-14 proximity ligation assay detects early non-inclusion alpha-synuclein pathology with enhanced specificity and sensitivity

Lewy pathology, consisting of Lewy bodies and Lewy neurites, is the pathological hallmark of synucle-inopathies such as Parkinsons disease and dementia with Lewy bodies, but it is generally thought to represent late-stage pathological changes. In contrast, -synuclein oligomers are regarded as early-stage pathology, likely involved in disease progression and cellular toxicity. Oligomers, however, are not de-tected by standard immunohistochemistry but require specific detection techniques such as the proxim-ity ligation assay (PLA). Here, we describe the MJF-14 PLA, a new PLA towards aggregated -synuclein with unprecedented specificity, attained by the utilization of aggregate conformation-specific -synu-clein antibody MJFR-14-6-4-2 (hereafter MJF-14). Signal in the assay directly correlates with -synuclein aggregation in SH-SY5Y cells, as treatment with aggregation inhibitor ASI1D significantly lowers PLA sig-nal. In human cortical neurons, MJF-14 PLA detects pre-formed fibril-induced aggregation, especially prominent when using stealth PFFs invisible to the MJF-14 antibody. Co-labelling of MJF-14 PLA and pS129--synuclein immunofluorescence in post-mortem dementia with Lewy bodies cases showed that while the MJF-14 PLA reveals extensive non-inclusion pathology, it is not sensitive towards Lewy bodies. In Parkinsons disease brain, direct comparison of PLA and IHC with the MJF-14 antibody, combined with machine learning-based quantification, showed striking -synuclein pathology preceding the formation of conventional Lewy pathology. The majority of the PLA-revealed non-inclusion pathology was found in the neuropil, including some clearly located in the presynaptic terminals. With this work, we introduce an improved -synuclein aggregate PLA to uncover abundant non-inclusion pathology, which deserves future validation with multiple brain bank resources and in different synucleinopathies.

neuroscience↗

bioRxiv2024

High Throughput Repurposing Screen Reveals Compounds with Activity Against Toxoplasma gondii Bradyzoites

Toxoplasma gondii causes widespread chronic infections that are not cured by current treatments due to inability to affect semi-dormant bradyzoite stages within tissue cysts. To identify compounds to eliminate chronic infection, we developed a HTS using a recently characterized strain of T. gondii that undergoes efficient conversion to bradyzoites in intro. Stage-specific expression of luciferase was used to selectively monitor growth inhibition of bradyzoites by the Library of Pharmacological Active Compounds, consisting of 1,280 drug-like compounds. We identified 44 compounds with >50% inhibitory effects against bradyzoites, including new highly potent compounds, several of which have precedent for antimicrobial activity. Subsequent characterization of the compound Sanguinarine sulfate revealed potent and rapid killing against in vitro produced bradyzoites and bradyzoites harvested from chronically infected mice. These findings provide a platform for expanded screening and identify promising compounds for further preclinical development against T. gondii bradyzoites responsible for chronic infection.

microbiology↗

bioRxiv2024

Structural basis for transcription activation through cooperative recruitment of MntR

The manganese transport regulator (MntR) from B. subtilis is a dual regulatory protein that responds to heightened Mn2+ availability in the cell by both repressing the expression of uptake transporters and activating the expression of efflux proteins. Recent work indicates that, in its role as an activator, MntR binds several sites upstream of the genes encoding Mn2+ exporters, leading to a cooperative response to manganese. Here, we use cryo-EM to explore the molecular basis of gene activation by MntR and report a structure of four MntR dimers bound to four 18-base pair sites across an 84-base pair regulatory region of the mneP promoter. Our structures, along with solution studies including mass photometry and in vivo transcription assays, reveal that MntR dimers employ polar and non-polar contacts to bind cooperatively to an array of low-affinity DNA-binding sites. These results reveal the molecular basis for cooperativity in the activation of manganese efflux.

biochemistry↗

bioRxiv2024

Drought resistance and improved yield result from modified malate metabolism in guard and vascular companion cells

Drought is a major threat to food security. Water loss through stomata is an inevitable consequence of CO2 uptake, and water deficit inhibits plant growth, making it challenging to develop drought-resistant strategies without compromising yield. Here, we generated tobacco plants expressing a maize NADP-dependent malate decarboxylating enzyme in stomata and vascular cells (ME plants), which show higher seed yield and faster maturation compared to wild-type (WT) plants under normal irrigation and after drought. While WT plants die after 45 days of drought, ME plants survive without any adverse effects on seed production. In addition, ME plants exhibit improved photosynthetic efficiency despite reduced stomatal conductance and changes in stem morphology, which are likely related to their ability to withstand drought. We propose that enhanced C4-like biochemistry in cells surrounding the vascular system and increased sugar export likely compensated for the reduced stomatal conductance in ME plants. The study demonstrates that cell-targeted metabolic modifications can avoid pleiotropic effects and facilitate the stacking of beneficial traits to improve crop design. Significance StatementDrought is one of the biggest threats to global food security, and its impact on crop yield is expected to worsen due to climate change. Traditionally, drought resistance has often come at the expense of yield, creating a negative trade-off. However, we present here a promising solution to this challenge. We have developed a novel approach that successfully uncouples the negative balance between drought resistance and yield. By introducing a maize enzyme into specific tobacco cells, we have created drought-resistant plants with faster growth and higher seed yield. Most importantly, after prolonged drought, while the wild type dies, the modified plants maintain their high yield. This technology paves the way for greater food security and resilience to climate change.

plant biology↗

bioRxiv2024

Emergent ecological advantage of sequential metabolic strategies in complex microbial communities

Microbes growing in fluctuating environments employ two key metabolic strategies: sequential (diauxic) utilization and co-utilization of nutrients. Most work has focused on understanding and comparing these strategies physiologically for the growth of single species, rather than ecologically for the assembly of complex natural communities. This is in part because of the lack of good metrics quantifying the fitness of different metabolic strategies in ecological contexts. Here, we present a new consumer-resource framework that incorporates dynamic proteome reallocation, and use it to compare the fitness of metabolic strategies during community assembly. We introduce two notions of fitness of a strategy in fluctuating environments: the time-averaged growth rate and the biomass-weighted prevalence of microbes using a given strategy. We find that sequential utilizers, although disadvantaged in pairwise competitions, gain a significant edge during community assembly -- an advantage that becomes more pronounced with increasing community diversity and the size of the species pool from which they are assembled. Low diversity communities resemble pairwise competitions and are dominated by co-utilizers, whereas high diversity, mature communities are dominated by the sequential utilizers. This shift is driven by two factors: the difference in lag times and the increased structural stability conferred by sequential strategies. Overall, our work provides several testable predictions about the co-occurrence patterns of microbes using different metabolic strategies.

ecology↗

bioRxiv2024

Natural killer cell migration in HIV-infected individuals is inhibited by impairment of HIF-1alpha-mediated glycolysis

Natural killer (NK) cells serve as the first line of defense of the immune system and play a crucial role in fighting against HIV infection. The effective function of NK cells is closely related to their migration ability, but the status of NK cell migration in HIV-infected individuals and the regulation mechanism for NK cell migration remains unknown. Here, we found that NK cell migration was significantly impaired in HIV-infected individuals, lower in immune non-responders (INRs) compared with immune responders (IRs), and positively correlated with CD4+ T cell counts. Further investigations showed that the decreased NK cell migration in HIV infection was caused by the impairment of glycolysis. Mechanistically, we found that NK cell migration was regulated by HIF-1 pathway, and inhibitory receptor TIGIT restrained HIF-1 expression by inhibiting PI3K/AKT/mTORC1 or ERK signaling pathway, consequently weakening the glycolysis of NK cells in HIV-infected individuals, and ultimately leading to down-regulation of migration. Collectively, we uncovered a mechanism of reduced NK cell migration in HIV infection and provided a new insight for immunotherapy in HIV infection. In BriefThe effective function of NK cells is closely related to its migration ability. The authors show that impaired NK cell migration in HIV-infected individuals is caused by TIGIT inhibiting HIF-1-mediated glycolysis via PI3K/AKT/mTORC1 or ERK pathway.

immunology↗

bioRxiv2024

Spatiotemporally resolved transcriptome atlas of developing mouse placenta reveals mechanisms of embryonic lethality.

Proper placentation is fundamental to the growth and viability of the maturing embryo. However, a thorough grasp of the spatial organization of cell types, their interactions, and gene expression patterns along the maternal-fetal function during placental development remains incomplete. Here, we utilized Stereo-seq to construct the spatiotemporal transcriptomic atlas of the mouse placenta (STAMP) spanning embryonic (E) days 9.5 to 18.5 at single cell resolution (https://db.cngb.org/stomics/stamp/). This resource delineates spatially resolved cellular dynamics and gene expression patterns across placental and maternal compartments. We identified distinct glycogen trophoblast cell (GC) subclusters, mapped their developmental trajectories, and uncovered transcriptional transitions accompanying their migration from the junctional zone to the maternal decidua from E12.5 onward. In a defective placentation model with perinatal lethality, GCs abnormally persisted at E18.5 with excessive glycogen and reduced degradation metabolites in placenta and fetal liver, indicating impaired glycogen breakdown. Maternal glucose supplementation restored glucose levels and rescued fetal survival, underscoring GC-mediated metabolic support as critical for viability. Together, this study provides a comprehensive spatiotemporal placental atlas and demonstrates that GC-mediated glycogen metabolism is essential for sustaining fetal viability.

developmental biology↗

bioRxiv2024

Peripheral B Lymphocyte Serves as A Reservoir for The Persistently Covert Infection of Mandarinfish Siniperca chuatsi Ranavirus

Genus Ranavirus in family Iridoviridae is composed of large members with various genomic sizes and viral gene contents, infecting a variety of ectothermic vertebrates including reptile, amphibians and bony fish worldwide. Mandarinfish ranavirus (MRV) is a very distinctive member among genus Ranavirus. Persistently convert infection of MRV were previously observed in natural outbreak of MRV, but the underlying mechanism remains unclear. We here evidenced that mandarinfish peripheral B lymphocytes are implemented as viral reservoirs to maintain persistent and covert infection. When mandarinfish were infected with sublethal dosage of MRV under nonpermissive temperature (19 {o}C) and permissive temperature (26 {o}C), respectively, all fish in 19 {o}C group survived and entered persistent phase of infection characterized with very low viral load in white blood cell, whereas partial fish died of MRV infection in 26 {o}C group, and the survivals then initiated persistent status. Gradually raising temperature, vaccination and dexamethasone treatment can reactivate the quiescent MRV to replicate and result in partial mortality. The viral reservoir investigates showed that IgM+-labelled B lymphocytes but not CD3{Delta}+-labelled T lymphocytes and MRC-1+-labelled macrophages are target cells for the persistent infection of MRV. Moreover, the quiescent MRV could not be reactivated by heat-killed Escherichia coli, indicating a very different reactivation mechanism from that of other known rannaviral member. Collectively, we are the first to confirm the presence of B cell-dependent persistent and covert infection of ranavirus, and provide a new clue for better understanding the complex infection mechanism of vertebrate iridovirus, especially regarding ranavirus. IMPORTANCEViruses known as HIV, HBV and EBV etc. evade host immune clearance by establishing long-term even lifelong persistent or latent infection. In vertebrate iridovirus, FV3, the type species of genus Ranavirus was evidenced to establish persistent infection by using Xenopus peritoneal macrophages as reservoirs. MRV is a very distinctive ranavirus from FV3 with very different genomic content and host species. We here uncovered MRV establishes persistent and covert infection by using peripheral B lymphocytes as virus reservoirs. During persistent infection, very low copies of quiescent MRV were harbored in peripheral B lymphocytes. Water temperature stress, vaccination stimulation, and dexamethasone treatment can reactivate quiescent MRV to replicate in abundance via a non-TLR5-mediated manner, and results in recurrence of MRV disease. Our finding suggests the diversity and complexity of the pathogenic mechanisms among ranaviruses, and also has important scientific significance for in-depth understanding of the infection and immunity interaction of vertebrate iridoviruses.

microbiology↗