Publications by authors named "Weiquan Liu"

37 Publications

DDA-Net: Unsupervised cross-modality medical image segmentation via dual domain adaptation.

Comput Methods Programs Biomed 2021 Nov 14;213:106531. Epub 2021 Nov 14.

Fujian Key Laboratory of Sensing and Computing for Smart Cities, Department of Computer Science, School of Informatics, Xiamen University, Xiamen 361005, China. Electronic address:

Background And Objective: Deep convolutional networks are powerful tools for single-modality medical image segmentation, whereas generally require semantic labelling or annotation that is laborious and time-consuming. However, domain shift among various modalities critically deteriorates the performance of deep convolutional networks if only trained by single-modality labelling data.

Methods: In this paper, we propose an end-to-end unsupervised cross-modality segmentation network, DDA-Net, for accurate medical image segmentation without semantic annotation or labelling on the target domain. To close the domain gap, different images with domain shift are mapped into a shared domain-invariant representation space. In addition, spatial position information, which benefits the spatial structure consistency for semantic information, is preserved by an introduced cross-modality auto-encoder.

Results: We validated the proposed DDA-Net method on cross-modality medical image datasets of brain images and heart images. The experimental results show that DDA-Net effectively alleviates domain shift and suppresses model degradation.

Conclusions: The proposed DDA-Net successfully closes the domain gap between different modalities of medical image, and achieves state-of-the-art performance in cross-modality medical image segmentation. It also can be generalized for other semi-supervised or unsupervised segmentation tasks in some other field.
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http://dx.doi.org/10.1016/j.cmpb.2021.106531DOI Listing
November 2021

A deep learning model for detection and tracking in high-throughput images of organoid.

Comput Biol Med 2021 07 25;134:104490. Epub 2021 May 25.

Fujian Key Laboratory of Sensing and Computing for Smart City, School of Informatics, Xiamen University, Xiamen, 361005, China. Electronic address:

Organoid, an in vitro 3D culture, has extremely high similarity with its source organ or tissue, which creates a model in vitro that simulates the in vivo environment. Organoids have been extensively studied in cell biology, precision medicine, drug toxicity, efficacy tests, etc., which have been proven to have high research value. Periodic observation of organoids in microscopic images to obtain morphological or growth characteristics is essential for organoid research. It is difficult and time-consuming to perform manual screens for organoids, but there is no better solution in the prior art. In this paper, we established the first high-throughput organoid image dataset for organoids detection and tracking, which experienced experts annotate in detail. Moreover, we propose a novel deep neural network (DNN) that effectively detects organoids and dynamically tracks them throughout the entire culture. We divided our solution into two steps: First, the high-throughput sequential images are processed frame by frame to detect all organoids; Second, the similarities of the organoids in the adjacent frames are computed, and the organoids on the adjacent frames are matched in pairs. With the help of our proposed dataset, our model achieves organoids detection and tracking with fast speed and high accuracy, effectively reducing the burden on researchers. To our knowledge, this is the first exploration of applying deep learning to organoid tracking tasks. Experiments have demonstrated that our proposed method achieved satisfactory results on organoid detection and tracking, verifying the great potential of deep learning technology in this field.
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http://dx.doi.org/10.1016/j.compbiomed.2021.104490DOI Listing
July 2021

Optic disc and optic cup segmentation based on anatomy guided cascade network.

Comput Methods Programs Biomed 2020 Dec 27;197:105717. Epub 2020 Aug 27.

Fujian Key Laboratory of Sensing and Computing for Smart Cities, Department of Computer Science, School of Informatics, Xiamen University, Xiamen 361005, China.

Background And Objective: Glaucoma, a worldwide eye disease, may cause irreversible vision damage. If not treated properly at an early stage, glaucoma eventually deteriorates into blindness. Various glaucoma screening methods, e.g. Ultrasound Biomicroscopy (UBM), Optical Coherence Tomography (OCT), and Heidelberg Retinal Scanner (HRT), are available. However, retinal fundus image photography examination, because of its low cost, is one of the most common solutions used to diagnose glaucoma. Clinically, the cup-to-disk ratio is an important indicator in glaucoma diagnosis. Therefore, precise fundus image segmentation to calculate the cup-to-disk ratio is the basis for screening glaucoma.

Methods: In this paper, we propose a deep neural network that uses anatomical knowledge to guide the segmentation of fundus images, which accurately segments the optic cup and the optic disc in a fundus image to accurately calculate the cup-to-disk ratio. Optic disc and optic cup segmentation are typical small target segmentation problems in biomedical images. We propose to use an attention-based cascade network to effectively accelerate the convergence of small target segmentation during training and accurately reserve detailed contours of small targets.

Results: Our method, which was validated in the MICCAI REFUGE fundus image segmentation competition, achieves 93.31% dice score in optic disc segmentation and 88.04% dice score in optic cup segmentation. Moreover, we win a high CDR evaluation score, which is useful for glaucoma screening.

Conclusions: The proposed method successfully introduce anatomical knowledge into segmentation task, and achieve state-of-the-art performance in fundus image segmentation. It also can be used for both automatic segmentation and semiautomatic segmentation with human interaction.
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http://dx.doi.org/10.1016/j.cmpb.2020.105717DOI Listing
December 2020

Molecular characteristics of the capsid protein VP2 gene of canine parvovirus type 2 amplified from raccoon dogs in Hebei province, China.

Arch Virol 2020 Nov 7;165(11):2453-2459. Epub 2020 Aug 7.

Key Laboratory of Special Animal Epidemic Disease of Ministry of Agriculture and Rural Affairs, Institute of Special Animals and Plants Sciences, Chinese Academy of Agricultural Sciences, No. 4899 Juye Street, Changchun, 130112, Jilin, China.

Canine parvovirus type 2 (CPV-2) is currently circulating in domestic and wild animals, but our knowledge about CPV-2 infections in raccoon dogs is limited. In this study, VP2 gene sequences of CPV-2 were amplified from rectal swabs of 14 diarrhetic raccoon dogs (Nyctereutes procyonoides) in Hebei province, China, in 2016 and 2017. Phylogenetic analysis of the VP2 gene sequences revealed that most of these sequences (11 of 14) belonged to the same subclade as raccoon dog strain CPV-2/Raccoon_Dog/China/DP-1/16 isolated from Shandong province in 2016. A comparison of deduced amino acid sequences revealed presence of the substitutions S297A and S27T in 11 of those 14 sequences. I418T was observed in a minority of the sequences (4 of 14). In addition, A300D and T301I, P13S and I219V, and N419K were found in three of the sequences. This study shows that CPV-2 strains with different substitutions in their VP2 amino acid sequences were spreading among raccoon dogs in Hebei during 2016 and 2017 and suggests that further studies are needed to monitor the distribution of these strains in China.
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http://dx.doi.org/10.1007/s00705-020-04714-3DOI Listing
November 2020

Whole Genome Characterization and Genetic Evolution Analysis of a New Ostrich Parvovirus.

Viruses 2020 03 19;12(3). Epub 2020 Mar 19.

College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266019, China.

Ostrich diseases characterized by paralysis have been breaking out in broad areas of China since 2015, causing major damage to the ostrich breeding industry in China. This report describes a parvovirus detected in ostriches from four different regions. The entire genomes of four parvovirus strains were sequenced following amplification by PCR, and we conducted comprehensive analysis of the ostrich parvovirus genome. Results showed that the length genomes of the parvovirus contained two open reading frames. Ostrich parvovirus (OsPV) is a branch of goose parvovirus (GPV). Genetic distance analysis revealed a close relationship between the parvovirus and goose parvovirus strains from China, with the closest being the 2016 goose parvovirus RC16 strain from Chongqing. This is the first report of a parvovirus in ostriches. However, whether OsPV is the pathogen of ostrich paralysis remains uncertain. This study contributes new information about the evolution and epidemiology of parvovirus in China, which provides a new way for the study of paralysis in ostriches.
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http://dx.doi.org/10.3390/v12030334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150892PMC
March 2020

RNAi-Mediated Gene Silencing of Induces a Hyperbranching Phenotype in .

J Microbiol Biotechnol 2020 Feb;30(2):206-215

Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China.

is the major filamentous fungus used to produce cellulase and there is huge interest in promoting its ability to produce higher titers of cellulase. Among the many factors affecting cellulase production in , the mycelial phenotype is important but seldom studied. Herein, a close homolog of the COT1 kinase was discovered in and designated COT1, which is of 83.3% amino acid sequence identity. Functional disruption of in by RNAi-mediated gene silencing resulted in retarded sporulation on potato dextrose agar and dwarfed colonies on minimal medium agar plates containing glucose, xylan, lactose, xylose, or glycerol as the sole carbon source. The representative mutant strain, SUS2/Trcot1i, also displayed reduced mycelia accumulation but hyperbranching in the MM glucose liquid medium, with hyphal growth unit length values decreased to 73.0 µm/tip compared to 239.8 µm/tip for the parent strain SUS2. The hyperbranching phenotype led to slightly but significantly increased cellulase secretion from 24 to 72 h in a batch culture. However, the cellulase production per unit of mycelial biomass was much more profoundly improved from 24 to 96 h.
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http://dx.doi.org/10.4014/jmb.1909.09050DOI Listing
February 2020

Bacterial magnetosomes loaded with doxorubicin and transferrin improve targeted therapy of hepatocellular carcinoma.

Nanotheranostics 2019 8;3(3):284-298. Epub 2019 Jul 8.

Beijing Advanced Innovation Center for Food Nutrition and Human Health, State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.

High metastatic rate and recurrence of tumor because of tumor circulating cells are seriously hinders for clinical tumor therapy. Herein, we develop a novel, activetargeting nanotherapeutic by simultaneously loading doxorubicin (DOX) and transferrin (Tf) onto bacterial magnetosomes (Tf-BMs-DOX) and investigate its antitumor efficacy and . Drug release profiles indicated that Tf-BMs/BMs loaded with DOX were capable of sustained drug release, suggesting that reduce drugs required frequency of administration and enhance their therapeutic effect. The results of cellular uptake revealed that Tf-BMs-DOX recognized hepatocellular carcinoma HepG2 cells more specifically compared to HL-7702 normal hepatocytes because of high expression of transferrin receptor (TfR) on the surface of HepG2 cells. Tf-BMs-DOX increased tumor cytotoxicity and apoptosis more significantly than free DOX or BMs-DOX by regulating the expression of tumorrelated and apoptosisrelated genes. Following intravenous injection in HepG2 cellbearing mice, Tf-BMs-DOX displayed tumor suppression rate of 56.78%, significantly higher than that of the BMs-DOX (41.53%) and free DOX (31.26%) groups. These results suggest that Tf-BMs-DOX have the potential to actively target to tumor sites, as well as the ability to kill circulating tumor cells via intravenous injection. Our findings provide a promising candidate for the clinical treatment of metastatic cancer.
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http://dx.doi.org/10.7150/ntno.34601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6696728PMC
June 2020

Growth-inhibitory effects of anthracycline-loaded bacterial magnetosomes against hepatic cancer and .

Nanomedicine (Lond) 2019 07 6;14(13):1663-1680. Epub 2019 Jun 6.

Beijing Advanced Innovation Center for Food Nutrition & Human Health, China Agricultural University, Yuanmingyuan West Road 2, Beijing 100193, PR China.

This study aimed to develop anthracycline-loaded bacterial magnetosomes (BMs) with enhanced anticancer efficiency and elucidate their endocytosis mechanism. Drug-loaded BMs (DBMs) were successfully prepared and characterized. DBMs endocytosis was investigated within HepG2 cells. The anticancer effect of DBMs was studied both and . Doxorubicin-BMs and daunorubicin-BMs showed enhanced growth inhibitory effect and with no notable toxicity to normal tissues. The DBMs were internalized into cells through caveolae-mediated endocytosis and macropinocytosis. The loaded drugs were released from DBMs in cytoplasm and entered the nucleus to exert their activity. Our findings offer promising candidates for improved cancer therapy with a clear mechanism of DBMs endocytosis and working principle.
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http://dx.doi.org/10.2217/nnm-2018-0296DOI Listing
July 2019

Establishment of a rescue system for porcine parvovirus using a seamless cloning method.

Arch Virol 2019 May 18;164(5):1459-1467. Epub 2019 Mar 18.

Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.

In this study, we describe a novel and rapid method for the construction of a full-length infectious clone (pPPV). The constructed clone contained an engineered EcoRv site that served as a genetic marker and was shown to be infectious when transfected into a monolayer of PK-15 cells. The rescued virus (rPPV) of the infectious clone was found to be indistinguishable from wild-type virus BQ in terms of its biological properties. The generation of this PPV infectious clone provides a potentially powerful tool with which to elucidate the molecular pathogenesis of PPV.
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http://dx.doi.org/10.1007/s00705-019-04209-wDOI Listing
May 2019

Oncolytic activity of canine distemper virus in canine mammary tubular adenocarcinoma cells.

Vet Comp Oncol 2019 Jun 24;17(2):174-183. Epub 2019 Mar 24.

The Clinical Department, College of Veterinary Medicine, China Agricultural University, Beijing, P.R. China.

Canine distemper virus (CDV), bearing a close resemblance to measles virus, represents a promising candidate for oncolytic therapy; however, its application and underlying oncolytic mechanisms in canine mammary carcinoma cells remain to be explored. Here, we found that an attenuated canine distemper vaccine strain, CDV-L, efficiently infected and inhibited the growth of canine mammary tubular adenocarcinoma CIPp cells but not MDCK cells in vitro. Transcriptomic analysis of CDV-L-infected CIPp cells revealed substantially differentially expressed genes in apoptotic and NF-κB signalling pathways. Subsequent validations confirmed that CDV-L-induced apoptosis of CIPp cells through the caspase-8 and caspase-3 pathway. Identification of phosphorylated-IκBα, phosphorylated-p65 and the nuclear translocation of p65 confirmed the activation of the NF-κB signalling pathway. Inhibition of the NF-κB pathway abrogated CDV-L-induced cleaved-caspase-3 and cleaved-PARP. In a CIPp subcutaneous xenograft mouse model, intratumoural injections of CDV-L significantly restricted tumour growth without apparent pathology, and virus remained localized within the tumour. Taken altogether, these findings indicate that CDV-L exerts an antitumour effect in CIPp cells, and that apoptosis and the NF-κB pathway play essential roles in this process.
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http://dx.doi.org/10.1111/vco.12466DOI Listing
June 2019

Naturally-occurring right terminal hairpin mutations in three genotypes of canine parvovirus (CPV-2a, CPV-2b and CPV-2c) have no effect on their growth characteristics.

Virus Res 2019 02 14;261:31-36. Epub 2018 Dec 14.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China. Electronic address:

We have isolated 4 naturally-occurring strains of CPV in mainland China and have identified them as CPV-2, 2a, 2b and 2c genotypes according to their VP2 sequences which also revealed substitutions within their right terminal regions. To determine if these substitutions affected the growth characteristics of the 4 strains, we constructed plasmids based on their genomic sequences minus their right terminal sequences, with the latter replaced by a single right terminal region. Analysis of rescued recombinants showed that the substitutions within their natural right termini had no significant effect on their growth characteristics.
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http://dx.doi.org/10.1016/j.virusres.2018.12.007DOI Listing
February 2019

Development of a reverse genetics system for a feline panleukopenia virus.

Virus Genes 2019 Feb 5;55(1):95-103. Epub 2018 Dec 5.

Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Science, 666 Liuying Xi Road, Changchun, 130122, China.

Feline panleukopenia virus (FPV) infects cats and can be fatal to kittens. There is evidence that canine parvovirus originated from FPV, which makes FPV important in studies of the family Parvoviridae. In the present study, the entire genome of FPV strain HH-1/86 was converted into a full-length infectious clone (pFPV). The FPV strain HH-1/86 has a 5123-nt single stranded DNA genome with a Y-shaped inverted 3' terminal repeat (ITR) and a U-shaped inverted 5' ITR. Feline kidney cells (F81) were transfected with the pFPV clone which contained a genetic marker, and a rescued virus was obtained (rFPV). The rFPV was identified by its cytopathic effects, indirect immunofluorescence, growth curve analysis, western blot assay and hemagglutination, and was indistinguishable from the parent virus. The FPV infectious clone will facilitate the study of pathogenicity and viral replication of FPV and the inter-species transmission of parvoviruses.
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http://dx.doi.org/10.1007/s11262-018-1621-9DOI Listing
February 2019

A versatile system for fast screening and isolation of cellulase hyperproducers based on DsRed and fluorescence-assisted cell sorting.

Biotechnol Biofuels 2018 24;11:261. Epub 2018 Sep 24.

1Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing, 100081 People's Republic of China.

Background: In the biofuel industry, cellulase plays an indispensable role in hydrolyzing cellulose into fermentable glucose. is a popular filamentous fungus with prominent ability to produce cellulase. While classical mutagenesis and modern multiplex genome engineering are both effective ways to improve cellulase production, successful obtaining of strains with improved cellulase-producing ability requires screening a large number of strains, which is time-consuming and labor intensive.

Results: Herein, we developed a versatile method coupling expression of the red fluorescence protein (DsRed) in and fluorescence-assisted cell sorting (FACS) of germinated spores. This method was first established by expressing DsRed intracellularly under the control of the major cellulase promoter in , which allowed us to rapidly isolate cellulase hyperproducers from progenies transformed with a dedicated transcriptional activator and from an atmospheric and room temperature plasma-created mutant library. Since intracellularly expressed DsRed was expected to isolate mutations mainly affecting cellulase transcription, this method was further improved by displaying DsRed on the cell surface, enabling isolation of strains with beneficial genetic alterations (overexpressing and ) affecting regulatory stages beyond transcription. Using this method, cellulase hyperproducers were also successfully isolated from an -mediated random insertional mutant library.

Conclusions: The coupled DsRed-FACS high-throughput screening method proved to be an effective strategy for fast isolation of cellulase hyperproducers and could also be applied in other industrially important filamentous fungi.
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http://dx.doi.org/10.1186/s13068-018-1264-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6151939PMC
September 2018

The 5' Untranslated Region of the Capsid Protein 2 Gene of Mink Enteritis Virus Is Essential for Its Expression.

J Virol 2018 09 29;92(18). Epub 2018 Aug 29.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China

Mink enteritis virus (MEV), as a parvovirus, is among the smallest of the animal DNA viruses. The limited genome leads to multifunctional sequences and complex gene expression regulation. Here, we show that the expression of viral capsid protein 2 (VP2) of MEV requires its 5' untranslated regions (5' UTR) which promote VP2 gene expression at both transcriptional and translational levels. The expression of VP2 was inhibited in several common eukaryotic expression vectors. Our data showed that the 5' UTR of VP2 enhanced capsid gene transcription but not increased stability or promotes nucleocytoplasmic export of VP2 mRNA. Analysis of the functions of 5' UTR fragments showed that the proximal region (nucleotides [nt] 1 to 270; that is, positions +1 to +270 relative to the transcription initiation site, nt 2048 to 2317 of MEV-L) of 5' UTR of VP2 was necessary for VP2 transcription and also promoted the activity of P38 promoter. Unexpectedly, further analysis showed that deletion of the distal region (nt 271 to 653) of the 5' UTR of VP2 almost completely abolished VP2 translation in the presence of P38, whereas the transcription was still induced significantly. Furthermore, using a luciferase reporter bicistronic system, we identified that the 5' UTR had an internal ribosome entry site-like function which could be enhanced by NS1 via the site at nt 382 to 447. Mutation of the 5' UTR in the MEV full-length clones further showed that the 5' UTR was required for VP2 gene expression. Together, our data reveal an undiscovered function of 5' UTR of MEV VP2 in regulating viral gene expression. MEV, a parvovirus, causes acute enteritis in mink. In the present report, we describe an untranslated sequence-dependent mechanism by which MEV regulates capsid gene expression. Our results highlight the roles of untranslated sequences in regulating the transcriptional activity of P38 promoter and translation of capsid genes. These data also reveal the possibility of an unusual translation mechanism in capsid protein expression and the multiple functions of nonstructural protein. A better understanding of the gene expression regulation mechanism of this virus will help in the design of new vaccines and targets for antiviral agents against MEV.
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http://dx.doi.org/10.1128/JVI.00787-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146693PMC
September 2018

MiR-7 Mediates the Zearalenone Signaling Pathway Regulating FSH Synthesis and Secretion by Targeting FOS in Female Pigs.

Endocrinology 2018 08;159(8):2993-3006

State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China.

Zearalenone (ZEA) acts as an environmental endocrine disruptor (EED) to cause health detriments. miRNAs were reported to influence the synthesis and secretion of pituitary hormones. However, the interactions between ZEA and miRNAs and related mechanisms remain unclear. The aims of this study were to determine whether and how miR-7 affects animal reproduction by its interactions with ZEA in the pig pituitary, which is sensitive to ZEA and has been used as an important animal model in medical research. Expressions of miRNA were detected by real-time PCR, in situ hybridization, and immunohistochemistry. The effects of ZEA, miR-7, and their interactions in the pituitary gland were identified by using an ovariectomized pig model, transfecting miR-7 mimics and inhibitor, radioimmunoassay, luciferase reporter assay, and Western blotting. The ZEA dosage was 7.5 mg/kg body weight in vivo and 1 μM in vitro. Our results demonstrate miR-7 acts to regulate gonadotropin synthesis and secretion. Furthermore, we found that ZEA leads to reproductive defects by enhancing miR-7 expression, which subsequently inhibits FSH synthesis and secretion. In vitro and in vivo experiments revealed that the effects of ZEA rely on G protein-coupled estrogen receptor 1, and miR-7 functions by mediating ZEA signaling pathway and targeting the Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog (FOS) gene. These findings show that miRNAs are key intrinsic factors regulating pituitary gonadotropins by mediating EED signaling in pituitary glands, and the actions of miRNAs and EEDs should be seriously considered in related studies about medical practice and animal production.
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http://dx.doi.org/10.1210/en.2018-00097DOI Listing
August 2018

Generation of an infectious clone of AMDV and identification of capsid residues essential for infectivity in cell culture.

Virus Res 2017 10 18;242:58-65. Epub 2017 Sep 18.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, China. Electronic address:

Pathogenic strains of Aleutian mink disease virus (AMDV) such as Utah-1 do not replicate in cell culture (e.g., Crandell Rees feline kidney cells) while the in vitro-adapted AMDV strain ADV-Gorham (ADV-G) is not pathogenic. Here, we constructed a full-length infectious clone (pADV-G). Alignment of the VP2 gene of ADV-G with that of other AMDV strains revealed many amino acid (a.a.) residues conserved among pathogenic isolates that differed in ADV-G. Four virulence-associated, conserved residues of pADV-G VP2 were studied by site-directed mutagenesis (H92A, Q94S, Y115F, and I116L). Mutation of residue 92 or 94 decreased viral-transcription and viral-infectivity levels, whereas mutation of residue 115 or 116 did not affect viral-infectivity in CRFK cells. These results indicated that VP2 residues 92 and 94, both located on the surface of the viral capsid, are critical for AMDV infectivity in vitro.
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http://dx.doi.org/10.1016/j.virusres.2017.09.011DOI Listing
October 2017

A rapid method for establishment of a reverse genetics system for canine parvovirus.

Virus Genes 2017 Dec 14;53(6):876-882. Epub 2017 Aug 14.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

Canine parvovirus (CPV) is an important and highly prevalent pathogen of dogs that causes acute hemorrhagic enteritis disease. Here, we describe a rapid method for the construction and characterization of a full-length infectious clone (rCPV) of CPV. Feline kidney (F81) cells were transfected with rCPV incorporating an engineered EcoR I site that served as a genetic marker. The rescued virus was indistinguishable from that of wild-type virus in its biological properties.
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http://dx.doi.org/10.1007/s11262-017-1497-0DOI Listing
December 2017

Induction and suppression of type I interferon responses by mink enteritis virus in CRFK cells.

Vet Microbiol 2017 Feb 5;199:8-14. Epub 2016 Dec 5.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China. Electronic address:

Mink enteritis virus (MEV) is one of the most important viral pathogens causing serious disease in mink. Type I interferon (IFN) plays a critical role in antiviral innate immunity and, for successful infection, many viruses have evolved evasive strategies against it. Here, we show that MEV infection does not evoke IFN or interferon-stimulated genes (ISGs) responses in feline kidney (CRFK) cells, and that MEV suppresses IFN production in both poly I:C-stimulated and untreated cells. In CRFK cells pre-exposure to IFN, show that infection with, and replication of, MEV remain unaffected. This inhibition appears to be mediated by the MEV nonstructural protein (NS1) with its ORI-binding domain playing a major role.
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http://dx.doi.org/10.1016/j.vetmic.2016.12.002DOI Listing
February 2017

Roles of three amino acids of capsid proteins in mink enteritis parvovirus replication.

Virus Res 2016 08 19;222:24-28. Epub 2016 May 19.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China. Electronic address:

Virulent mink enteritis parvovirus (MEV) strain MEV-LHV replicated to higher titers in feline F81 cells than attenuated strain MEV-L. Phylogenetic and sequence analyses of the VP2 gene of MEV-LHV, MEV-L and other strains in GenBank revealed two evolutionary branches separating virulent and attenuated strains. Three residues, 101, 232 and 411, differed between virulent and attenuated strains but were conserved within the two branches. Site-directed mutagenesis of the VP2 gene of infectious plasmids of attenuated strain MEV-L respectively replacing residues 101 Ile and 411 Ala with Thr and Glu of virulent strains (MEV-L I101T and MEV-L A411E) increased replication efficiency but still to lower levels than MEV-LHV. However, viruses with mutation of residue 232 (MEV-L I232V and MEV-L I101T/I232V/A411E) decreased viral transcription and replication levels. The three VP2 residues 101, 232 and 411, located on or near the capsid surface, played different roles in the infection processes of MEV.
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http://dx.doi.org/10.1016/j.virusres.2016.05.019DOI Listing
August 2016

Genetic characterization of the complete genome of an Aleutian mink disease virus isolated in north China.

Virus Genes 2016 Aug 23;52(4):463-73. Epub 2016 Mar 23.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

The genome of a highly pathogenic strain of Aleutian disease mink virus (AMDV-BJ) isolated from a domestic farm in North China has been determined and compared with other strains. Alignment analysis of the major structural protein VP2 revealed that AMDV-BJ is unique among 17 other AMDV strains. Compared with the nonpathogenic strain ADV-G, the 3' end Y-shaped hairpin was highly conserved, while a 4-base deletion in the 5' U-shaped terminal palindrome resulted in a different unpaired "bubble" group near the NS1-binding region of the 5' end hairpin which may affect replication efficiency in vivo. We also performed a protein analysis of the NS1, NS2, and new-confirmed NS3 of AMDV-BJ with some related AMDV DNA sequence published, providing information on evolution of AMDV genes. This study shows a useful method to obtain the full-length genome of AMDV and some other parvoviruses.
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http://dx.doi.org/10.1007/s11262-016-1320-3DOI Listing
August 2016

Comparison of biological and genomic characteristics between a newly isolated mink enteritis parvovirus MEV-LHV and an attenuated strain MEV-L.

Virus Genes 2016 Jun 18;52(3):388-96. Epub 2016 Mar 18.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

A virus isolated from mink showing clinical signs of enteritis was identified as a high virulent mink enteritis parvovirus (MEV) based on its biological characteristics in vivo and in vitro. Mink, challenged with this strain named MEV-LHV, exhibited severe pathological lesions as compared to those challenged with attenuated strain MEV-L. MEV-LHV also showed higher infection and replication efficiencies in vitro than MEV-L. Sequence of the complete genome of MEV-LHV was determined and analyzed in comparison with those in GenBank, which revealed that MEV-LHV shared high homology with virulent strain MEV SD12/01, whereas MEV-L was closely related to Abashiri and vaccine strain MEVB, and belonged to a different branch of the phylogenetic tree. The genomes of the two strains differed by insertions and deletions in their palindromic termini and specific unique mutations (especially VP2 300) in coding sequences which may be involved in viral replication and pathogenicity. The results of this study provide a better understanding of the biological and genomic characteristics of MEV and identify certain regions and sites that may be involved in viral replication and pathogenicity.
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http://dx.doi.org/10.1007/s11262-016-1314-1DOI Listing
June 2016

The phosphorylation of Ser221 in VP2 of mink enteritis virus and its roles in virus amplification.

Virus Res 2016 06 10;217:76-84. Epub 2016 Mar 10.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China. Electronic address:

Recent reports have indicated that phosphorylation of capsid proteins plays an important role in virion assemblage. Autonomous parvoviruses are among the smallest known viruses with an ssDNA genome enclosed within an icosahedral capsid. Here, we demonstrate that a structural protein (VP2) of one member, mink enteritis virus (MEV), is phosphorylated at serine-221 (Ser221) in vivo. Mutant viruses containing an S221A non-phosphorylatable alanine substitution, or an S221E glutamic acid substitution to mimic serine phosphorylation, were able to express VP2 but had either limited ability or were unable to propagate in feline F81 cells. We propose a new mechanism whereby VP2 phosphorylation plays an essential role in amplification during MEV infection.
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http://dx.doi.org/10.1016/j.virusres.2016.03.004DOI Listing
June 2016

A recombinant canine distemper virus expressing a modified rabies virus glycoprotein induces immune responses in mice.

Virus Genes 2015 Jun 13;50(3):434-41. Epub 2015 Mar 13.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

Canine distemper virus (CDV) and rabies virus (RV) are two important pathogens of the dog. CDV, a member of the morbillivirus genus, has shown promise as an expression vector. The glycoprotein from RV is a main contributor to protective immunity and capable of eliciting the production of virus-neutralizing antibodies. In this study, we recovered an attenuated strain of canine distemper virus and constructed a recombinant virus, rCDV-RV-G, expressing a modified (R333Q) rabies virus glycoprotein (RV-G) of RV Flury strain LEP. RV-G expression by the recombinant viruses was confirmed. Furthermore, G was proved to be incorporated into the surface of CDV particles. While replication of the recombinant virus was slightly reduced compared with the parental CDV, it stably expressed the RV-G over ten serial passages. Inoculation of mice induced specific neutralizing antibodies against both RV-G and CDV. Therefore, the rCDV-RV-G has the potential as a vaccine that may be used to control rabies virus infection in dogs and other animals.
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http://dx.doi.org/10.1007/s11262-015-1169-xDOI Listing
June 2015

MicroRNA miR-320a and miR-140 inhibit mink enteritis virus infection by repression of its receptor, feline transferrin receptor.

Virol J 2014 Dec 3;11:210. Epub 2014 Dec 3.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

Mink enteritis virus (MEV) is one of the most important pathogens in the mink industry. Recent studies have shed light into the role of microRNAs (miRNAs), small noncoding RNAs of length ranging from 18-23 nucleotides (nt), as critical modulators in the host-pathogen interaction networks. We previously showed that miRNA miR-181b can inhibit MEV replication by repression of viral non-structural protein 1 expression. Here, we report that two other miRNAs (miR-320a and miR-140) inhibit MEV entry into feline kidney (F81) cells by downregulating its receptor, transferrin receptor (TfR), by targeting the 3' untranslated region (UTR) of TfR mRNA, while being themselves upregulated.
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http://dx.doi.org/10.1186/s12985-014-0210-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4264318PMC
December 2014

Overexpression of Banna mini-pig inbred line fatty acid binding protein 3 promotes adipogenesis in 3T3-L1 preadipocytes.

Cell Biol Int 2014 Aug 28;38(8):918-23. Epub 2014 Apr 28.

Department of Biochemistry and Molecular Biology, State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.

Fatty acid binding protein 3 (H-FABP, FABP3) has been significantly associated with intramuscular fat (IMF) content in pigs, which is positively correlated with palatability of pork. However, its underlying function is not fully elucidated. We have investigated the effects of overexpression of the FABP3 gene on differentiation and adipogenesis of 3T3-L1 preadipocytes in the fat Banna mini-pig inbred line (fBMIL). Eukaryotic vectors that expressed the FABP3 protein were constructed, and stably established in the 3T3-L1 preadipocytes cell line. Cells were induced in a standard differentiation cocktail. Morphological changes and the degree of adipogenesis were measured by Oil Red O staining assay and triacylglycerol content measurement, respectively. mRNA expression levels of triacylglycerol metabolism-related genes were measured by qPCR. FABP3 significantly promoted differentiation of 3T3-L1 cells and enhanced triacylglycerol levels (P < 0.05). mRNA of the peroxisome proliferator-activated receptor γ (PPARγ), adipocyte fatty acid binding protein (422/aP2) and glycerol-3-phosphate dehydrogenase (GPDH) gene increased markedly (P < 0.05). In conclusion, expression of the FABP3 gene enhances adipogenesis in 3T3-L1 preadipocytes primarily by upregulating lipogenic PPARγ, 422/aP2 and GPDH genes.
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http://dx.doi.org/10.1002/cbin.10285DOI Listing
August 2014

Potentiation of Apoptin-induced apoptosis by Cecropin B-like antibacterial peptide ABPs1 in human HeLa cervical cancer cell lines is associated with membrane pore formation and caspase-3 activation.

J Microbiol Biotechnol 2014 Jun;24(6):756-64

State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, P. R. China.

Apoptin, a chicken anemia virus-encoded protein, induces apoptosis in chicken or human tumor cells, localizing in their nuclei as opposed to the cytoplasm of non-transformed cells. The present study was undertaken to investigate whether ABPs1 could potentiate apoptininduced apoptosis in HeLa cells. ABPs1 and the apoptin genes were successfully cloned into pIRES2-EGFP expression vector and expressed in HeLa cells. We report that ABPs1 augments apoptin cell growth inhibition in a concentration- and time-dependent manner. The DAPI staining and scanning electron microscopy observations revealed apoptotic bodies and plasma membrane pores, which were attributed to apoptin and ABPs1, respectively. Further, ABPs1 in combination with apoptin was found to increase the expression of Bax and to decrease the expression of survivin compared with either agent alone or the control. The apoptotic rate of HeLa cells treated with ABPs1 and apoptin in combination for 48 h was 53.95%. The two-gene combination increased the caspase-3 activity of HeLa cells. Taken together, our study suggests that ABPs1 combined with apoptin significantly inhibits HeLa cell proliferation, and induces cell apoptosis through membrane defects, up-regulation of Bax expression, down-regulation of survivin expression, and activation of the caspase-3 pathway. Thus, the combination of ABPs1 and apoptin could serve as a means to develop novel gene therapeutic agents against human cervical cancer.
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http://dx.doi.org/10.4014/jmb.1209.09076DOI Listing
June 2014

MicroRNA profile analysis of a feline kidney cell line before and after infection with mink enteritis virus.

Gene 2014 Apr 11;539(2):224-9. Epub 2014 Feb 11.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, China. Electronic address:

MicroRNAs (miRNAs) are small regulatory RNAs that play a significant role in eukaryotes by targeting mRNAs for cleavage or translational repression. Recent studies have also shown them to be associated with cellular changes following viral infection. Mink enteritis virus (MEV) is one of the most important viral pathogens in the mink industry. To study the involvement of miRNAs in the MEV infection process, we used Illumina's ultrahigh throughput approach to sequencing miRNA libraries from the feline kidney (F81) cell line before and after infection with MEV. Using this bioinformatics approach we identified 196 known mammalian miRNA orthologs belonging to 152 miRNA families in F81 cells. Additionally, 97 miRNA*s of these miRNAs were detected. As well as known miRNAs, 384 and 398 novel miRNA precursor candidates were identified in uninfected and MEV-infected F81 cells respectively that have not been reported in other mammals. In MEV-infected cells 3 miRNAs were significantly down-regulated and 4 up-regulated including 3 significantly. The majority (12 of 16) of randomly selected miRNA expression profiles by qRT-PCR were consistent with those identified by deep sequencing. A total of 88 miRNAs were predicted to target interferon-associated genes; 6 appear to target the 3'UTR of MEV-specific receptor transferring receptor mRNAs; and 8 to target the MEV mRNA coding region. No miRNAs coded by MEV itself were detected.
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http://dx.doi.org/10.1016/j.gene.2014.01.074DOI Listing
April 2014

Establishment of a rescue system for an autonomous Parvovirus mink enteritis virus.

Virus Res 2014 Apr 22;183:1-5. Epub 2014 Jan 22.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China. Electronic address:

Construction and characterization of a full-length infectious clone (pMEV) of mink enteritis virus are described. Feline kidney cells (F81) were transfected with pMEV containing an engineered BamHI site that served as a genetic marker. The rescued virus was indistinguishable from its parental virus. The availability of a MEV infectious clone will facilitate studies of viral replication and pathogenicity and will permit the elucidation of determinants of the host range of the parvovirus.
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http://dx.doi.org/10.1016/j.virusres.2014.01.012DOI Listing
April 2014

Cellular microRNA miR-181b inhibits replication of mink enteritis virus by repression of non-structural protein 1 translation.

PLoS One 2013 11;8(12):e81515. Epub 2013 Dec 11.

State Key Laboratory of Agrobiotechnology, Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, China.

Mink enteritis virus (MEV) is one of the most important viral pathogens in the mink industry. Recent studies have showed that microRNAs (miRNAs), small noncoding RNAs of length ranging from 18-23 nucleotides (nt) participate in host-pathogen interaction networks; however, whether or not miRNAs are involved in MEV infection has not been reported. Our study revealed that miRNA miR-181b inhibited replication of MEV in the feline kidney (F81) cell line by targeting the MEV non-structural protein 1 (NS1) messenger RNA (mRNA) coding region, resulting in NS1 translational repression, while MEV infection reduced miR-181b expression. This is the first description of cellular miRNAs modulating MEV infection in F81 cells, providing further insight into the mechanisms of viral infection, and may be useful in development of naturally-occurring miRNAs antiviral strategies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0081515PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3859502PMC
September 2014

Porcine reproductive and respiratory syndrome virus activates inflammasomes of porcine alveolar macrophages via its small envelope protein E.

Virology 2013 Aug 8;442(2):156-62. Epub 2013 May 8.

Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei, Hebei Engineering and Technology Research Center of Veterinary Biological Products, Baoding, China.

Porcine reproductive and respiratory syndrome virus (PRRSV) infection results in extensive tissue inflammation and damage, which are believed to be responsible for increased susceptibility to secondary infection and even for death. However, its pathogenic mechanisms are not fully understood. To explore the mechanism underlying the PRRSV-induced tissue inflammation and damage, we investigated whether PRRSV activates porcine alveolar macrophage (PAM) inflammasomes which mediate por-IL-1β maturation/release and subsequently induce tissue inflammation and injury. Our results showed that PRRSV and its small envelope protein E significantly increased IL-1β release from LPS-primed PAMs; however, only PRRSV not protein E significantly increased IL-1β release from no-LPS-primed PAMs, which indicates PRRSV can activate inflammasomes of PAMs by its encoded protein E. These results provide a molecular basis for the pathogenic mechanism of PRRSV on inducing extensive tissue inflammation and damage, and suggest that the inflammasome may provide a potential therapeutic target for PRRS prevention and treatment.
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http://dx.doi.org/10.1016/j.virol.2013.04.007DOI Listing
August 2013
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