Biology subjects

Wang, R.

Publications and source records attributed to Wang, R..

At least 325 records · Page 18Linked to original sources

bioRxiv2023

MYC-driven increases in mitochondrial DNA copy number occur early and persist throughout prostatic cancer progression

Increased mitochondrial function may render some cancers vulnerable to mitochondrial inhibitors. Since mitochondrial function is regulated partly by mitochondrial DNA copy number (mtDNAcn), accurate measurements of mtDNAcn could help reveal which cancers are driven by increased mitochondrial function and may be candidates for mitochondrial inhibition. However, prior studies have employed bulk macrodissections that fail to account for cell type-specific or tumor cell heterogeneity in mtDNAcn. These studies have often produced unclear results, particularly in prostate cancer. Herein, we developed a multiplex in situ method to spatially quantify cell type specific mtDNAcn. We show that mtDNAcn is increased in luminal cells of high-grade prostatic intraepithelial neoplasia (HGPIN), is increased in prostatic adenocarcinomas (PCa), and is further elevated in metastatic castration-resistant prostate cancer. Increased PCa mtDNAcn was validated by two orthogonal methods and is accompanied by increases in mtRNAs and enzymatic activity. Mechanistically, MYC inhibition in prostate cancer cells decreases mtDNA replication and expression of several mtDNA replication genes, and MYC activation in the mouse prostate leads to increased mtDNA levels in the neoplastic prostate cells. Our in situ approach also revealed elevated mtDNAcn in precancerous lesions of the pancreas and colon/rectum, demonstrating generalization across cancer types using clinical tissue samples.

cancer biology↗

bioRxiv2023

LRG1 is a novel ligand of HER3 and promotes metastatic colorectal cancer growth

Therapy failure for patients with metastatic colorectal cancer (mCRC) remains an overarching challenge in the clinic. We find that liver endothelial cells secrete soluble factor(s) to promote mCRC growth in vitro and in vivo. We identify LRG1 in ECs secretome, which promotes growth in tumor cells through binding and activation of HER3. Pharmacological blocking of the LRG1/HER3 axis using LRG1 antibody 15C4 completely attenuated LRG1-induced HER3 activation and in vitro and in vivo growth of the tumor. Moreover, LRG1-/- mice with CRC allografts in the liver had 2 times longer overall survival than tumor-bearing LRG1+/+ mice. Lastly, unbiased -omics analysis and target-specific inhibitors identified eIF4-protein synthesis is significantly activated by the LRG1/HER3/RSK1/2 axis. This work reveals a paracrine mechanism of mCRC growth in liver microenvironment and highlighted the potential of blocking LRG1-HER3 and involved downstream pathways for treating patients with mCRC. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC="FIGDIR/small/529070v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1a84299org.highwire.dtl.DTLVardef@1ac6654org.highwire.dtl.DTLVardef@1723260org.highwire.dtl.DTLVardef@4970a8_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

CRB3 navigates Rab11 trafficking vesicles to promote γTuRC assembly during ciliogenesis

The primary cilium plays important roles in regulating cell differentiation, signal transduction, and tissue organization. Dysfunction of the primary cilium can lead to ciliopathies and cancer. The formation and organization of the primary cilium are highly associated with cell polarity proteins, such as the apical polarity protein CRB3. However, the molecular mechanisms by which CRB3 regulates ciliogenesis and the location of CRB3 remain unknown. Here, we show that CRB3, as a navigator, regulates vesicle trafficking in {gamma}-TuRC assembly during ciliogenesis and cilium-related Hh and Wnt signaling pathways in tumorigenesis. Crb3 knockout mice display severe defects of the primary cilium in the mammary ductal lumen and renal tubule, while mammary epithelial-specific Crb3 knockout mice exhibit the promotion of ductal epithelial hyperplasia and tumorigenesis. CRB3 is essential for lumen formation and ciliary assembly in the mammary epithelium. We demonstrate that CRB3 localizes to the basal body and that CRB3 trafficking is mediated by Rab11-positive endosomes. Significantly, CRB3 interacts with Rab11 to navigate GCP6/Rab11 trafficking vesicles to CEP290, resulting in intact {gamma}-TuRC assembly. In addition, CRB3-depleted cells are unresponsive to the activation of the Hh signaling pathway, while CRB3 regulates the Wnt signaling pathway. Therefore, our studies reveal the molecular mechanisms by which CRB3 recognizes Rab11-positive endosomes to facilitate ciliogenesis, and regulates cilium-related signaling pathways in tumorigenesis.

cell biology↗

bioRxiv2023

xTrimoDock: Rigid Protein Docking via Cross-Modal Representation Learning and Spectral Algorithm

Protein-protein interactions are the basis for the formation of protein complexes which are essential for almost all cellular processes. Knowledge of the structures of protein complexes is of major importance for understanding the biological function of these protein-protein interactions and designing protein drugs. Here we address the problem of rigid protein docking which assumes no deformation of the involved proteins during interactions. We develop a method called, xTrimoDock, which leverages a cross-modal representation learning to predict the protein distance map, and then uses a spectral initialization and gradient descent to obtain the roto-translation transformation for docking. We show that, on antibody heavy-chain and light-chain docking, and antibody-antigen docking, xTrimoDock consistently outperforms the state-of-the-art such as AlphaFold-Multimer and HDock, and can lead to as much as a 10% improvement in DockQ metric. xTrimoDock has been applied as a useful tool in protein drug design at BioMap.

bioinformatics↗

bioRxiv2023

PLANET: A Multi-Objective Graph Neural Network Model for Protein-Ligand Binding Affinity Prediction

Predicting protein-ligand binding affinity is a central issue in drug design. Various deep learning models have been developed in recent years to tackle this issue, but many of them merely focus on reproducing the binding affinity of known binders. In this study, we have developed a graph neural network model called PLANET (Protein-Ligand Affinity prediction NETwork). This model takes the graph-represented 3D structure of the binding pocket on the target protein and the 2D chemical structure of the ligand molecule as input, and it was trained through a multi-objective process with three related tasks, including deriving the protein-ligand binding affinity, protein-ligand contact map, and intra-ligand distance matrix. To serve those tasks, a large number of decoy non-binders were selected and added to the standard PDBbind data set. When tested on the CASF-2016 benchmark, PLANET exhibited a scoring power comparable to other deep learning models that rely on 3D protein-ligand complex structures as input. It also showed notably better performance in virtual screening trials on the DUD-E and LIT-PCBA benchmark. In particular, PLANET achieved comparable accuracy on LIT-PCBA as the conventional docking program Glide. However, it only took less than 1% of the computation time required by Glide to finish the same job because it did not perform exhaustive conformational sampling. In summary, PLANET exhibited a decent performance in binding affinity prediction as well as virtual screening, which makes it potentially useful for drug discovery in practice.

bioinformatics↗

bioRxiv2023

Multifunctional ferromagnetic fiber robots for navigation, sensing, and treatment in minimally invasive surgery

Small-scale robots capable of remote active steering and navigation offer great potential for biomedical applications. However, the current design and manufacturing procedure impede their miniaturization and integration of various diagnostic and therapeutic functionalities. Here, we present a robotic fiber platform for integrating navigation, sensing, and therapeutic functions at a submillimeter scale. These fiber robots consist of ferromagnetic, electrical, optical, and microfluidic components, fabricated with a thermal drawing process. Under magnetic actuation, they can navigate through complex and constrained environments, such as artificial vessels and brain phantoms. Moreover, we utilize Langendorff mouse hearts model, glioblastoma microplatforms, and in vivo mouse models to demonstrate the capabilities of sensing electrophysiology signals and performing localized treatment. Additionally, we demonstrate that the fiber robots can serve as endoscopes with embedded waveguides. These fiber robots provide a versatile platform for targeted multimodal detection and treatment at hard-to-reach locations in a minimally invasive and remotely controllable manner.

bioengineering↗

bioRxiv2023

The complete chloroplast genome sequence of Akebia trifoliata and a comparative analysis within the Ranales clade

The complete nucleotide sequence of the Akebia trifoliata chloroplast (cp) genome was reported and characterized in this study. The cp genome is a closed circular molecule of 157 949 bp, composed of a pair of IR regions of 26 149 bp, one LSC region of 86 595 bp, and one SSC region of 19 056 bp. The GC contents of the LSC, SSC, and IR regions, and the whole cp genome are 37.11%, 33.62%, 43.08% and 38.66%, respectively. The cp genome contains 130 predicted functional genes, including 85 PCGs of 79 107 bp, 37 tRNA and 8 rRNA genes of 11 851 bp. 168 SSRs and 23 long repeats were identified in the cp genome. The results revealed that 21 891 codons characterize the coding capacity of 85 protein-coding genes in Akebia trifoliata, 10.84% and 1.20% of the codons coded for leucine and cysteine respectively. The usage of the start codon exhibited no bias in the A. trifoliata cp genome. Phylogenetic analysis suggest that A. trifoliata is most closely related to S. japonica, which then formed a cluster with N. dormestica and M. saniculifolia to form subgroup of Ranunculales. Our study provides information on mangrove plant species in coastal intertidal zones.

plant biology↗

bioRxiv2023

Preclinical Basis of the Efficacy and Pharmacodynamics of Finotonlimab, a Humanized Anti-PD-1 Monoclonal Antibody with Potent Implications for Clinical Benefit

BackgroundThe antibodies of programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have dramatically changed the treatment landscapes for patients with cancer. Clinical uses of PD-1 antibodies have greatly improved the overall survival and durable responses in patients across selected tumor types. MethodsWe describe the preclinical characterization of Finotonlimab, a humanized anti-PD-1 antibody, by head to head comparison with Nivolumab or Pembrolizumab. Herein, we characterized the in vitro and in vivo efficacy, PK, PD and Fc mediated effector function of Finotonlimab. The single-agent anti-tumor activity of Finotonlimab was evaluated using humanized mouse models and a human PBMC reconstituted mouse model. Furthermore, in cynomolgus monkeys, comparative PK measurements confirmed better PK profiles of Finotonlimab than that of Pembrolizumab and Nivolumab. ResultsOur data showed Finotonlimab bind to human PD-1 with significantly high affinity and effectively inhibited its interaction with its ligands, PD-L1 and PD-L2, and thus could effectively stimulate the human T cell functions in vitro and exhibited significant antitumor efficacy in vivo. In addition, Finotonlimab showed minimal impact on Fc receptor dependent effector cell activation, which may contribute to the killing of PD-1+ T cells. In cynomolgus monkeys, Finotonlimab exhibited a non-linear pharmacokinetics (PK) profile in a dose-dependent manner, and approximately 90% of consistent receptor occupancy period was observed at 168 h after a single administration of 1 mg/kg. Following a 13-week successive administration of Finotonlimab, a pharmacodynamics study indicated a sustained mean receptor occupancy of [≥] 93% of PD-1 molecules on circulating T cells in cynomolgus monkeys up to 8 weeks even at 3 mg/kg. ConclusionsTaken together, these preclinical data are encouraging and provide a basis for the efficacy and pharmacodynamics of Finotonlimab in clinical trials.

immunology↗

bioRxiv2023

A cinnamyl alcohol dehydrogenase (CAD) like enzyme leads to a branch in the shikonin biosynthetic pathway in Arnebia euchroma

Shikonin derivatives are natural naphthoquinone compounds and the main bioactive components produced by several boraginaceous plants, such as Lithospermum erythrorhizon and Arnebia euchroma. Phytochemical researches utilizing L. erythrorhizon and A. euchroma cultured cells both indicate the existence of a competing route branching out from the shikonin biosynthetic pathway toward benzo/hydroquinones. A previous study has shown that the branch point is a putative alcohol dehydrogenase converting (Z)-3-hydroxygeranylhydroquinone [(Z)-3-OH-GHQ] to an aldehyde intermediate (E)-3-oxo-GHQ. However, the enzyme involved in the branch reaction is not characterized at the molecular level yet. In this study, we clone a candidate gene belonging to the cinnamyl alcohol dehydrogenase (CAD) family, AeHGO, through coexpression analysis of transcriptome data sets of shikonin-proficient and shikonin-deficient cell lines of A. euchroma. In biochemical assays, purified AeHGO protein reversibly oxidizes (Z)-3-OH-GHQ to produce (E)-3-oxo-GHQ followed by reversibly reducing (E)-3-oxo-GHQ to (E)-3-OH-GHQ, resulting in an equilibrium mixture of the three compounds. Time course analysis and kinetic parameters show that the reaction with (Z)-3-OH-GHQ is about twice as efficient as with (E)-3-OH-GHQ, which leads to the predominance of (E)-3-OH-GHQ and (E)-3-oxo-GHQ in the equilibrium mixture. According to a previous report, (E)-3-oxo-GHQ can be converted to deoxyshikonofuran, a hydroquinone metabolite produced by boraginaceous plants. Considering there is a competition for accumulation between shikonin derivatives and benzo/hydroquinones in both L. erythrorhizon and A. euchroma cultured cells, AeHGO is supposed to play an important role in the metabolic regulation of shikonin biosynthetic pathway.

biochemistry↗

bioRxiv2023

Fluorescence Image Data with Sparse and Low-Rank Poisson Regression

Multispectral biological fluorescence microscopy has enabled the identification of multiple targets in complex samples. The accuracy in the unmixing result degrades (1) as the number of fluorophores used in any experiment increases and (2) as the signal-to-noise ratio in the recorded images decreases. Further, the availability of prior knowledge regarding the expected spatial distributions of fluorophores in images of labeled cells provides an opportunity to improve the accuracy of fluorophore identification and abundance. We propose a regularized sparse and low-rank Poisson unmixing approach (SL-PRU) to deconvolve spectral images labeled with highly overlapping fluorophores which are recorded in low signal-to-noise regimes. Firstly, SL-PRU implements multi-penalty terms when pursuing sparseness and spatial correlation of the resulting abundances in small neighborhoods simultaneously. Secondly, SL-PRU makes use of Poisson regression for unmixing instead of least squares regression to better estimate photon abundance. Thirdly, we propose a method to tune the SL-PRU parameters involved in the unmixing procedure in the absence of knowledge of the ground truth abundance information in a recorded image. By validating on simulated and real-world images, we show that our proposed method leads to improved accuracy in unmixing fluorophores with highly overlapping spectra.

bioinformatics↗

bioRxiv2022

Hypothalamic supramammillary neurons that project to the medial septum control wakefulness

The hypothalamic supramammillary nucleus (SuM) plays a key role in controlling wakefulness, but the downstream target regions participating in this control process remain unknown. Here, using circuit-specific fiber photometry and single-neuron electrophysiology together with electroencephalogram, electromyogram and behavioral recordings, we find approximately half of SuM neurons that project to the medial septum (MS) are wake-active. Optogenetic stimulation of axonal terminals of SuM-MS projection induces a rapid and reliable transition to wakefulness from NREM or REM sleep, and chemogenetic activation of SuMMS projecting neurons significantly increases wakefulness time and prolongs latency to sleep. Consistently, chemogenetically inhibiting these neurons significantly reduces wakefulness time and latency to sleep. Therefore, these results identify the MS as a functional downstream target of SuM and provide evidence for a causal role for this hypothalamic-septal projection in wakefulness control.

neuroscience↗

bioRxiv2022

The necessity of considering enzymes as compartments in constraint-based genomescale metabolic models

As the most widespread and practical digital representations of living cells, metabolic network models have become increasingly precise and accurate. By integrating cellular resources and abiotic constraints, the prediction functions were significantly expanded in recent years. However, we found that if unreasonable modeling methods were adopted due to the lack of consideration of biological knowledge, the conflicts between stoichiometric and other constraints, such as thermodynamic feasibility and enzyme resource availability, would lead to distorted predictions. In this work, we investigated a prediction anomaly of EcoETM, a constraints-based metabolic network model, and introduced the idea of enzyme compartmentalization into the analysis process. Through rational combination of reactions, we avoid the false prediction of pathway feasibility caused by the unrealistic assumption of free intermediate metabolites. This allowed us to correct the pathway structures of L-serine and L-tryptophan. Specific analysis explains the application method of EcoETM-like model, demonstrating its potential and value in correcting the prediction results in pathway structure by resolving the conflict between different constraints and incorporating the evolved roles of enzymes as reaction compartments. Notably, this work also reveals the trade-off between product yield and thermodynamic feasibility. Finally, we provide a preliminary comparison of the thermodynamic feasibility of ammonia and glutamine as amino donors, which revealed that the direct utilization of ammonia does not have a decisive impact on the thermodynamic feasibility of the anthranilate pathway. Our work is of great value for the structural improvement of constraints-based models.

bioinformatics↗

bioRxiv2022

Self-Supervised Maize Kernel Classification and Segmentation for Embryo Identification

Computer vision and deep learning (DL) techniques have succeeded in a wide range of diverse fields. Recently, these techniques have been successfully deployed in plant science applications to address food security, productivity, and environmental sustainability problems for a growing global population. However, training these DL models often necessitates the large-scale manual annotation of data which frequently becomes a tedious and time-and-resource-intensive process. Recent advances in self-supervised learning (SSL) methods have proven instrumental in overcoming these obstacles, using purely unlabeled datasets to pre-train DL models. Here, we implement the popular self-supervised contrastive learning methods of NNCLR (Nearest neighbor Contrastive Learning of visual Representations) and SimCLR (Simple framework for Contrastive Learning of visual Representations) for the classification of spatial orientation and segmentation of embryos of maize kernels. Maize kernels are imaged using a commercial high-throughput imaging system. This image data is often used in multiple downstream applications across both production and breeding applications, for instance, sorting for oil content based on segmenting and quantifying the scutellums size and for classifying haploid and diploid kernels. We show that in both classification and segmentation problems, SSL techniques outperform their purely supervised transfer learning-based counterparts and are significantly more annotation efficient. Additionally, we show that a single SSL pre-trained model can be efficiently finetuned for both classification and segmentation, indicating good transferability across multiple downstream applications. Segmentation models with SSL-pretrained backbones produce DICE similarity coefficients of 0.81, higher than the 0.78 and 0.73 of those with ImageNet-pretrained and randomly initialized backbones, respectively. We observe that finetuning classification and segmentation models on as little as 1% annotation produces competitive results. These results show SSL provides a meaningful step forward in data efficiency with agricultural deep learning and computer vision.

plant biology↗

bioRxiv2022

Tau pathology in the dorsal raphe may be a prodromal indicator of Alzheimer's disease

Protein aggregation in brainstem nuclei is thought to occur in the early stages of Alzheimers disease (AD), but its specific role in driving prodromal symptoms and disease progression is largely unknown. The dorsal raphe nucleus (DRN) contains a large population of serotonin (5-hydroxytryptamine; 5-HT) neurons that regulate mood, reward-related behavior, and sleep, which are all disrupted in AD. We report here that tau pathology is present in the DRN of individuals 54-80 years old without a known history of dementia and was found at higher frequency than -synuclein and TDP-43. Most AD cases had tau pathology in the DRN (90%), whereas only a subset contained TDP-43 or -synuclein, but not both (30%). To evaluate how early tau pathology impacts behavior, we overexpressed human P301L-tau in the DRN of mice and observed depressive-like behaviors and hyperactivity without any deficits in spatial memory. Tau pathology was predominantly found in neurons relative to glia and colocalized with a significant proportion of Tph2-expressing neurons in the DRN. 5-HT neurons were also hyperexcitable in P301L-tauDRN mice, and there was an increase in the amplitude of excitatory post-synaptic currents (EPSCs), suggestive of increased glutamatergic transmission. Moreover, astrocytic density was elevated in the DRN and accompanied by an increase in IL-1 and Frk expression, which is indicative of inflammation. Additionally, tau pathology was detected in axonal processes in the thalamus, hypothalamus, amygdala, and caudate putamen and a significant proportion of this tau pathology colocalized with the serotonin reuptake transporter (SERT), suggesting that tau may spread in an anterograde manner to regions outside the DRN. Together these results indicate that tau pathology accumulates in the DRN in a subset of individuals over 50 years and may lead to behavioral dysregulation, 5-HT neuronal dysfunction, and activation of local astrocytes which may be prodromal indicators of AD.

neuroscience↗

bioRxiv2022

Aryl hydrocarbon receptor utilises cellular zinc signals to maintain the gut epithelial barrier

Both zinc and plant-derived ligands of the aryl hydrocarbon receptor (AHR) are dietary components which regulate intestinal epithelial barrier function and protect against Inflammatory Bowel Disease (IBD)1,2. Here, we explore whether zinc and AHR pathway are linked using a mouse IBD model with follow-on studies on human and mouse ileum organoids. Our data demonstrate that AHR regulates cellular zinc uptake, and that zinc is an integral part of AHR signalling processes. We show that dietary supplementation in mice with the plant-derived AHR ligand precursor, indole-3-carbinol (I3C), offers a high level of protection against dextran sulfate sodium induced IBD while protection fails in mice with AHR deleted in the intestinal epithelium. AHR agonist treatment is also ineffective in mice with a nutritional zinc deficiency. Experiments in the human Caco-2 cell line and ileum organoids showed that AHR activation increases total cellular zinc and cytosolic free Zn2+ concentrations through transcriptional upregulation of several SLC39 zinc importers. As a consequence, genes for tight junction (TJ) proteins were upregulated in a zinc-dependent manner involving zinc inhibition of signalling to NF-{kappa}B and attenuated degradation of TJ proteins through zinc inhibition of calpain activity. Thus, our data indicate that AHR activation by plant-derived dietary ligands improves gut barrier function via zinc-dependent cellular pathways, suggesting that combined dietary supplementation with AHR ligands and zinc might be effective in preventing and treating inflammatory gut disorders.

cell biology↗

bioRxiv2022

Effect of Nrf2 Loss on Senescence and Cognition of Tau-Based P301S Mice

Cellular senescence may contribute to chronic inflammation involved in the progression of age-related diseases such as Alzheimers Disease (AD), and its removal prevents cognitive impairment in a model of tauopathy. Nrf2, the major transcription factor for damage response pathways and regulators of inflammation, declines with age. Our previous work showed that silencing Nrf2 gives rise to premature senescence in cells and mice. Others have shown that Nrf2 ablation can exacerbate cognitive phenotypes of some AD models. In this study we aimed to understand the relationship between Nrf2 elimination, senescence, and cognitive impairment in AD, by generating a mouse model expressing a mutant human tau transgene in an Nrf2 knockout (Nrf2KO) background. We assessed senescent cell burden and cognitive decline of P301S mice in the presence and absence of Nrf2. Lastly, we administered 4.5 month-long treatments with two senotherapeutic drugs to analyze their potential to prevent senescent cell burden and cognitive decline: the senolytic drugs Dasatinib and Quercetin (DQ) and the senomorphic drug rapamycin. Nrf2 loss accelerated the onset of hind-limb paralysis in P301S mice. At 8.5 months of age, P301S mice did not exhibit memory deficits, while P301S mice without Nrf2 were significantly impaired. However, markers of senescence were not elevated by Nrf2 ablation in any of tissues that we examined. Neither drug treatment improved cognitive performance, nor did it reduce expression of senescence markers in brains of P301S mice. Contrarily, rapamycin treatment at the doses used delayed spatial learning and led to a modest decrease in spatial memory. Taken together, our data suggests that the emergence of senescence may be causally associated with onset of cognitive decline in the P301S model, indicate that Nrf2 protects brain function in a model of AD through mechanisms that may include, but do not require the inhibition of senescence, and suggest possible limitations for DQ and rapamycin as therapies for AD.

animal behavior and cognition↗

bioRxiv2022

Leveraging functional genomic annotations and genome coverage to improve polygenic prediction of complex traits within and between ancestries

We develop a new method, SBayesRC, that integrates GWAS summary statistics with functional genomic annotations to improve polygenic prediction of complex traits. Our method is scalable to whole-genome variant analysis and refines signals from functional annotations by allowing them to affect both causal variant probability and causal effect distribution. We analyse 28 traits in the UK Biobank using [~]7 million common SNPs and 96 annotations. SBayesRC improves prediction accuracy by 14% in European ancestry and by up to 33% in trans-ancestry prediction, compared to the baseline method SBayesR which does not use annotations, and outperforms state-of-the-art methods LDpred-funct, PolyPred-S and PRS-CSx by 12-15%. Investigation of factors affecting prediction accuracy identified a significant interaction between SNP density and annotation information, encouraging future use of whole-genome sequence variants for prediction. Functional partitioning analysis highlights a major contribution of evolutionary constrained regions to prediction accuracy and the largest per-SNP contribution from non-synonymous SNPs.

genetics↗

bioRxiv2022

Increased public health threat of avian-origin H3N2 influenza virus during evolution in dogs

Influenza A viruses in animal reservoirs repeatedly cross species barrier to infect humans. Once an animal-borne virus with novel antigenicity acquired the efficient human to human transmissibility, it will become epidemic in the population. Dogs are the closest animal companions to humans and canine respiratory tract expresses both SA2,3-(avian type) and 2,6-Gal (human type) receptors. However, the role of dogs in the ecology of influenza viruses is unclear. H3N2 avian influenza viruses transmitted to dogs around 2006 and have formed stable lineages. The long-term epidemic of avian-origin H3N2 virus in canine offers the best models to investigate the effect of dogs on the evolution of influenza viruses. Here, we carried out a systematic and comparative identification of the biological characteristics of H3N2 canine influenza viruses (CIVs) isolated in the worldwide over 10 years. We found that during the adaptation of H3N2 CIVs to dogs, H3N2 CIVs became to recognize the human-like SA2,6-Gal receptor, gradually increased HA acid stability and replication ability in human airway epithelial cells, and acquired a 100% transmission rate via respiratory droplet in ferret model, which were essential hallmarks of being adapted to humans. We also identified that the frequency of substitutions related to human adaptation has gradually increased in H3N2 CIVs, and determined four cumulative molecular changes responsible for the increased airborne transmission ability in ferrets. Our results suggested that canine may serve as an intermediate for the adaptation of avian influenza virus to human. Continuous surveillance coordinated with risk assessment for CIVs is necessary.

microbiology↗