Publications by authors named "Xiaoyu Sang"

31 Publications

Comparative analysis of ketone body metabolism in BALB/c mice infected with Trypanosoma evansi and Toxoplasma gondii.

Res Vet Sci 2021 Dec 20;143:134-141. Epub 2021 Dec 20.

Key Laboratory of Livestock Infectious Diseases, Ministry of Education, China; College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang 110866, China. Electronic address:

KBs (ketone bodies), i.e., acetoacetate, acetone, and (R)-3-Hydroxybutanoate, constitute the intermediate products of the incomplete oxidative degradation of fatty acids. These KBs are used as a source of energy in the hosts' brain, skeletal muscles, and heart. Additionally, they regulate inflammation and oxidative stress of the host by acting as signaling mediators. Parasitic infection is known to result in abnormal physiological and biochemical metabolism, ketoacidosis, and other damage to the host. In this study, we investigated the effects of Trypanosoma evansi and Toxoplasma gondii on ketone body metabolism in mice, as well as the KB levels in the brain, liver, and peripheral blood. T. gondii was found to significantly increase the KB levels, resulting in ketonemia; T. evansi was found to stabilize KB levels in mice. Further investigations showed that T. evansi downregulated the expression of genes encoding enzymes involved in KBs synthesizing pathway and enhanced KBs synthesizing to eliminate ketonemia. Conversely, T. gondii significantly increased the expression of genes encoding enzymes involved in KBs synthesizing pathway and decreased KBs metabolism pathway ones and resulting in increased KBs levels in peripheral blood, culminating in ketonemia. These findings elucidate the differences in the KBs metabolism resulting from infection with T. evansi and T. gondii.
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http://dx.doi.org/10.1016/j.rvsc.2021.12.016DOI Listing
December 2021

Protein Lactylation Critically Regulates Energy Metabolism in the Protozoan Parasite .

Front Cell Dev Biol 2021 14;9:719720. Epub 2021 Oct 14.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.

Lysine lactylation has been recognized as a novel post-translational modification occurring on histones. However, lactylation in non-histone proteins, especially in proteins of early branching organisms, is not well understood. Energy metabolism and the histone repertoire in the early diverging protozoan parasite , the causative agent of African trypanosomiasis, markedly diverge from those of conventional eukaryotes. Here, we present the first exhaustive proteome-wide investigation of lactylated sites in . We identified 387 lysine-lactylated sites in 257 proteins of various cellular localizations and biological functions. Further, we revealed that glucose metabolism critically regulates protein lactylation in although the parasite lacks lactate dehydrogenase. However, unlike mammals, increasing the glucose concentration reduced the level of lactate, and protein lactylation decreased in a unique lactate production pathway. In addition to providing a valuable resource, these foregoing data reveal the regulatory roles of protein lactylation of trypanosomes in energy metabolism and gene expression.
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http://dx.doi.org/10.3389/fcell.2021.719720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8551762PMC
October 2021

Lipophosphoglycan Induces the Formation of Neutrophil Extracellular Traps and Reactive Oxygen Species Burst Toll-Like Receptor 2, Toll-Like Receptor 4, and c-Jun N-Terminal Kinase Activation.

Front Microbiol 2021 28;12:713531. Epub 2021 Jul 28.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Key Laboratory of Zoonosis, Ministry of Education, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.

is the causative agent of African animal trypanosomosis, which mainly parasitizes the blood of the host. Lipophosphoglycan (LPG), a polymer anchored to the surface of the parasites, activates the host immune response. In this study, we revealed that LPG stimulated neutrophils to form neutrophil extracellular traps (NETs) and release the reactive oxygen species (ROS). We further analyzed the involvement of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) and explored the activation of signaling pathway enzymes in response to LPG stimulation. During the stimulation of neutrophils by LPG, the blockade using anti-TLR2 and anti-TLR4 antibodies reduced the phosphorylation of c-Jun N-terminal kinase (JNK), the release of DNA from the NETs, and the burst of ROS. Moreover, the addition of JNK inhibitor and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor exhibited similar effects. Our data suggest that LPG activates the phosphorylation of JNK through TLR2 and TLR4 recognition, which causes the formation of NETs and the burst of ROS.
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http://dx.doi.org/10.3389/fmicb.2021.713531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8355521PMC
July 2021

Protein Modification Characteristics of the Malaria Parasite Plasmodium falciparum and the Infected Erythrocytes.

Mol Cell Proteomics 2021 24;20:100001. Epub 2020 Nov 24.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Shenyang Agricultural University, Shengyang, China; The Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, Shenyang, China. Electronic address:

Malaria elimination is still pending on the development of novel tools that rely on a deep understanding of parasite biology. Proteins of all living cells undergo myriad posttranslational modifications (PTMs) that are critical to multifarious life processes. An extensive proteome-wide dissection revealed a fine PTM map of most proteins in both Plasmodium falciparum, the causative agent of severe malaria, and the infected red blood cells. More than two-thirds of proteins of the parasite and its host cell underwent extensive and dynamic modification throughout the erythrocytic developmental stage. PTMs critically modulate the virulence factors involved in the host-parasite interaction and pathogenesis. Furthermore, P. falciparum stabilized the supporting proteins of erythrocyte origin by selective demodification. Collectively, our multiple omic analyses, apart from having furthered a deep understanding of the systems biology of P. falciparum and malaria pathogenesis, provide a valuable resource for mining new antimalarial targets.
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http://dx.doi.org/10.1074/mcp.RA120.002375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857547PMC
November 2020

TatD DNases of African trypanosomes confer resistance to host neutrophil extracellular traps.

Sci China Life Sci 2021 Apr 8;64(4):621-632. Epub 2021 Jan 8.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866, China.

African trypanosomatid parasites escape host acquired immune responses through periodic antigenic variation of their surface coat. In this study, we describe a mechanism by which the parasites counteract innate immune responses. Two TatD DNases were identified in each of Trypanosoma evansi and Trypanosoma brucei. These DNases are bivalent metal-dependent endonucleases localized in the cytoplasm and flagella of the parasites that can also be secreted by the parasites. These enzymes possess conserved functional domains and have efficient DNA hydrolysis activity. Host neutrophil extracellular traps (NETs) induced by the parasites could be hydrolyzed by native and recombinant TatD DNases. NET disruption was prevented, and the survival rate of parasites was decreased, in the presence of the DNase inhibitor aurintricarboxylic acid. These data suggest that trypanosomes can counteract host innate immune responses by active secretion of TatD DNases to degrade NETs.
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http://dx.doi.org/10.1007/s11427-020-1854-2DOI Listing
April 2021

Enhanced Antimalarial Efficacy Obtained by Targeted Delivery of Artemisinin in Heparin-Coated Magnetic Hollow Mesoporous Nanoparticles.

ACS Appl Mater Interfaces 2021 Jan 24;13(1):287-297. Epub 2020 Dec 24.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China.

Malaria is one of the deadliest infectious diseases threatening half of the world population. With the deterioration of the parasiticidal effect of the current antimalarials, novel approaches such as screening of more specific inhibitors and targeted delivery of drugs have been under intensive research. Herein, we prepare hollow mesoporous ferrite nanoparticles (HMFNs) of 200 nm with ferromagnetic properties using a one-pot hydrothermal reaction. A magnetically targeted drug-delivery system coloaded with artemisinin in the inner magnetite shell and heparin on the outer mesoporous shell ([email protected]@HEP) is developed. Specific targeting of the magnetic nanoparticles to the parasite-infected erythrocytes is achieved by the attraction between the HMFNs and hemozoin (paramagnetic), a vital metabolite of plasmodium in the erythrocytic stage. With the hemozoin production reaching the maximum during the schizont period of the parasite, [email protected]@HEPs are adsorbed to the infected red blood cells (iRBCs), which not only interferes with the release of merozoites but also significantly enhances the inhibitory efficacy due to the increased local concentration of artemisinin. Subsequently, the heparin coated on the surface of the nanoparticles can efficiently interfere with the invasion of freshly released merozoites to new RBCs through the specific interaction between the parasite-derived ligands and heparin, which further increases the inhibitory effect on malaria. As a cluster of heparin, heparin-coated nanoparticles provide stronger blocking capability than free heparin, resulting from multivalent interactions with surface receptors on merozoite. Thus, we have developed a HMFN-based delivery system with considerable antimalarial efficacy, which is a promising platform for treatment against malaria.
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http://dx.doi.org/10.1021/acsami.0c20070DOI Listing
January 2021

Interaction Analysis of a PHISTa-like Protein and PfEMP1 Proteins.

Front Microbiol 2020 13;11:611190. Epub 2020 Nov 13.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, Shenyang Agricultural University, Shenyang, China.

extensively remodels host cells by translocating numerous proteins into the cytoplasm of red blood cells (RBCs) after invasion. Among these exported proteins, members of the helical interspersed subtelomeric (PHIST) family are crucial for host cell remodeling and host-parasite interactions, and thereby contribute to malaria pathogenesis. Herein, we explored the function of PF3D7_1372300, a member of the PHIST/PHISTa-like subfamily. PF3D7_1372300 was highly transcribed and expressed during the blood stage of , and distributed throughout RBCs, but most abundant at the erythrocyte membrane. Specific interaction of PF3D7_1372300 with the cytoplasmic tail of erythrocyte membrane protein 1 (PfEMP1) was revealed by immunofluorescence assay, intermolecular interaction assays. The interaction sites of PF3D7_1372300 with PfEMP1 ATS domain were found involved more than 30 amino acids (aa) at several positions. The findings deepen our understanding of host-parasite interactions and malaria pathogenesis.
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http://dx.doi.org/10.3389/fmicb.2020.611190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7691434PMC
November 2020

Determination of lumefantrine as an effective drug against infection - and study.

Parasitology 2021 01 22;148(1):122-128. Epub 2020 Oct 22.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Dongling Road 120, 110866Shengyang, China.

Toxoplasma gondii is an obligate intracellular protozoan parasite, which can infect almost all warm-blooded animals, including humans, leading to toxoplasmosis. Currently, the effective treatment for human toxoplasmosis is the combination of sulphadiazine and pyrimethamine. However, both drugs have serious side-effects and toxicity in the host. Therefore, there is an urgent need for the discovery of new anti-T. gondii drugs with high potency and less or no side-effects. Our findings suggest that lumefantrine exerts activity against T. gondii by inhibiting its proliferation in Vero cells in vitro without being toxic to Vero cells (P ≤ 0.01). Lumefantrine prolonged mice infected with T. gondii from death for 3 days at the concentration of 50 μg L-1 than negative control (phosphate-buffered saline treated only), and reduced the parasite burden in mouse tissues in vivo (P ≤ 0.01; P ≤ 0.05). In addition, a significant increase in interferon gamma (IFN-γ) production was observed in high-dose lumefantrine-treated mice (P ≤ 0.01), whereas interleukin 10 (IL-10) and IL-4 levels increased in low-dose lumefantrine-treated mice (P ≤ 0.01). The results demonstrated that lumefantrine may be a promising agent to treat toxoplasmosis, and more experiments on the protective mechanism of lumefantrine should be undertaken in further studies.
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http://dx.doi.org/10.1017/S0031182020002036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808861PMC
January 2021

Landscapes of Protein Posttranslational Modifications of African Trypanosoma Parasites.

iScience 2020 May 18;23(5):101074. Epub 2020 Apr 18.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China; The Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang 110866, China. Electronic address:

Proteins of all living cells undergo a myriad of post-translational modifications (PTMs) that are critical to multifarious life processes. In this study, we describe the first comprehensive multiple PTM-omics atlas in parallel with quantitative proteome analyses of two representative species of African trypanosomes, Trypanosoma brucei and Trypanosoma evansi. Ten PTM types with approximately 40,000 modified sites and 150 histone marks with a fine map on each protein of the two African trypanosomes were accomplished. The two biologically different trypanosomal species displayed distinct PTM-omic features, regulation pathways, and networks. Modifications in the proteins involved in the redox system were mainly upregulated in T. brucei, whereas proteins associated with motility were predominantly modified in T. evansi. The establishment of a database of multiple PTMs in the two parasites provides us with a deep insight into the biological mechanisms that underpin life processes in trypanosomes with different life cycles.
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http://dx.doi.org/10.1016/j.isci.2020.101074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218301PMC
May 2020

The Putative TCP-1 Chaperonin Is an Important Player Involved in Sialic Acid-Dependent Host Cell Invasion by .

Front Microbiol 2020 21;11:258. Epub 2020 Feb 21.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.

Host cell invasion by is crucial for the survival and proliferation of parasite. The process of tachyzoite invasion requires interaction between parasite proteins and receptors on the surface of host cells. Sialic acid is one of the important receptors for host cell invasion by . However, the parasite-derived proteins interacting with sialic acid have not been well characterized. In this study, a novel protein named putative TCP-1 chaperonin (TGME49_318410) in (TgTCP-1) was targeted and characterized. TgTCP-1 protein colocalized with MIC3 protein, which could be secreted from tachyzoites, and this protein showed a specific binding activity to sialic acid, and DC and Vero cells . The binding of TgTCP-1 protein to DC and Vero cells were inhibited by either pre-incubation with free sialic acid or neuraminidase treatment of the cells. Moreover, a significant reduction of invasion in Vero cells was observed after pre-incubation of the cells with recombinant TgTCP-1 protein. These results illustrated that TgTCP-1 is an important molecule involved in sialic acid-dependent host cell invasion by .
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http://dx.doi.org/10.3389/fmicb.2020.00258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047128PMC
February 2020

A Sialic Acid-Binding Protein SABP1 of Toxoplasma gondii Mediates Host Cell Attachment and Invasion.

J Infect Dis 2020 06;222(1):126-135

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, Shenyang Agricultural University, Shenyang, China.

Many obligate intracellular apicomplexan parasites have adapted a distinct invasion mechanism involving a close interaction between the parasite ligands and the sialic acid (SA) receptor. We found that sialic acid binding protein-1 (SABP1), localized on the outer membrane of the zoonotic parasite Toxoplasma gondii, readily binds to sialic acid on the host cell surface. The binding was sensitive to neuraminidase treatment. Cells preincubated with recombinant SABP1 protein resisted parasite invasion in vitro. The parasite lost its invasion capacity and animal infectivity after the SABP1 gene was deleted, whereas complementation of the SABP1 gene restored the virulence of the knockout strain. These data establish the critical role of SABP1 in the invasion process of T. gondii. The previously uncharacterized protein, SABP1, facilitated T. gondii attachment and invasion via sialic acid receptors.
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http://dx.doi.org/10.1093/infdis/jiaa072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296849PMC
June 2020

Tim-3 signaling blockade with α-lactose induces compensatory TIGIT expression in Plasmodium berghei ANKA-infected mice.

Parasit Vectors 2019 Nov 11;12(1):534. Epub 2019 Nov 11.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866, China.

Background: Malaria, one of the largest health burdens worldwide, is caused by Plasmodium spp. infection. Upon infection, the host's immune system begins to clear the parasites. However, Plasmodium species have evolved to escape the host's immune clearance. T-cell immunoglobulin and mucin domain 3 (Tim-3), a surface molecule on most immune cells, is often referred to as an exhaustion marker. Galectin (Gal)-9 is a Tim-3 ligand and the T helper (Th) 1 cell response is inhibited when Gal-9 binds to Tim-3. In the present study, dynamic expression of Tim-3 on key populations of lymphocytes during infection periods of Plasmodium berghei and its significance in disease resistance and pathogenesis were explored.

Methods: Tim-3 expression on critical lymphocyte populations and the proportion of these cells, as well as the levels of cytokines in the sera of infected mice, were detected by flow cytometry. Further, in vitro anti-Tim-3 assay using an anti-Tim-3 antibody and in vivo Tim-3-Gal-9 signaling blockade assays using α-lactose (an antagonist of Gal-9) were conducted. An Annexin V Apoptosis Detection Kit with propidium iodide was used to detect apoptosis. In addition, proteins associated with apoptosis in lung and spleen tissues were confirmed by Western blotting assays.

Results: Increased Tim-3 expression on splenic CD8 and splenic CD4, and circulatory CD4 T cells was associated with a reduction in the proportion of these cells. Furthermore, the levels of interleukin (IL)-2, IL-4, IL-6, IL-22, and interferon (IFN)-γ, but not that of tumor necrosis factor alpha (TNF-α), IL-10, and IL-9, increased to their highest levels at day 4 post-infection and decreased thereafter. Blocking Tim-3 signaling in vitro inhibited lymphocyte apoptosis. Tim-3-Gal-9 signaling blockade in vivo did not protect the mice, but induced the expression of the immunosuppressive molecule, T cell immunoreceptor with Ig and ITIM domains (TIGIT), in Plasmodium berghei ANKA-infected mice.

Conclusions: Tim-3 on lymphocytes negatively regulates cell-mediated immunity against Plasmodium infection, and blocking Tim-3-galectin 9 signaling using α-lactose did not significantly protect the mice; however, it induced the compensatory expression of TIGIT. Further investigations are required to identify whether combined blockade of Tim-3 and TIGIT signaling could achieve a better protective effect.
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http://dx.doi.org/10.1186/s13071-019-3788-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849286PMC
November 2019

Global Lysine Crotonylation and 2-Hydroxyisobutyrylation in Phenotypically Different Parasites.

Mol Cell Proteomics 2019 11 5;18(11):2207-2224. Epub 2019 Sep 5.

Key Laoratory of Animal Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110166, China. Electronic address:

is a unicellular protozoan parasite of the phylum Apicomplexa. The parasite repeatedly goes through a cycle of invasion, division and induction of host cell rupture, which is an obligatory process for proliferation inside warm-blooded animals. It is known that the biology of the parasite is controlled by a variety of mechanisms ranging from genomic to epigenetic to transcriptional regulation. In this study, we investigated the global protein posttranslational lysine crotonylation and 2-hydroxyisobutyrylation of two strains, RH and ME49, which represent distinct phenotypes for proliferation and pathogenicity in the host. Proteins with differential expression and modification patterns associated with parasite phenotypes were identified. Many proteins in were crotonylated and 2-hydroxyisobutyrylated, and they were localized in diverse subcellular compartments involved in a wide variety of cellular functions such as motility, host invasion, metabolism and epigenetic gene regulation. These findings suggest that lysine crotonylation and 2-hydroxyisobutyrylation are ubiquitous throughout the proteome, regulating critical functions of the modified proteins. These data provide a basis for identifying important proteins associated with parasite development and pathogenicity.
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http://dx.doi.org/10.1074/mcp.RA119.001611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823851PMC
November 2019

Dihydroartemisinin regulates the immune system by promotion of CD8 T lymphocytes and suppression of B cell responses.

Sci China Life Sci 2020 May 8;63(5):737-749. Epub 2019 Jul 8.

Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, Shenyang Agricultural University, Shenyang, 110866, China.

Artemisia annua is an anti-fever herbal medicine first described in traditional Chinese medicine 1,000 years ago. Artemisinin, the extract of A. annua, and its derivatives (dihydroartemisinin (DHA), artemether, and artesunate) have been used for the treatment of malaria with substantial efficacy. Recently, DHA has also been tested for the treatment of lupus erythematosus, indicating that it may function to balance the immune response in immunocompromised individuals. In the present study, the regulatory effect of artemisinin on the murine immune system was systematically investigated in mice infected with two different protozoan parasites (Toxoplasma gondii and Plasmodium berghei). Our results revealed that the mouse spleen index significantly increased (spleen enlargement) in the healthy mice after DHA administration primarily due to the generation of an extra number of lymphocytes and CD8 T lymphocytes in both the spleen and circulation. DHA could increase the proportion of T helper cells and CD8 T cells, as well as decrease the number of splenic and circulatory B cells. Further, DHA could reduce the production of proinflammatory cytokines. Our study revealed that apart from their anti-parasitic activity, artemisinin and its derivatives can also actively modulate the immune system to directly benefit the host.
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http://dx.doi.org/10.1007/s11427-019-9550-4DOI Listing
May 2020

In-depth analysis of the genome of Trypanosoma evansi, an etiologic agent of surra.

Sci China Life Sci 2019 Mar 24;62(3):406-419. Epub 2019 Jan 24.

Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866, China.

Trypanosoma evansi is the causative agent of the animal trypanosomiasis surra, a disease with serious economic burden worldwide. The availability of the genome of its closely related parasite Trypanosoma brucei allows us to compare their genetic and evolutionarily shared and distinct biological features. The complete genomic sequence of the T. evansi YNB strain was obtained using a combination of genomic and transcriptomic sequencing, de novo assembly, and bioinformatic analysis. The genome size of the T. evansi YNB strain was 35.2 Mb, showing 96.59% similarity in sequence and 88.97% in scaffold alignment with T. brucei. A total of 8,617 protein-coding genes, accounting for 31% of the genome, were predicted. Approximately 1,641 alternative splicing events of 820 genes were identified, with a majority mediated by intron retention, which represented a major difference in post-transcriptional regulation between T. evansi and T. brucei. Disparities in gene copy number of the variant surface glycoprotein, expression site-associated genes, microRNAs, and RNA-binding protein were clearly observed between the two parasites. The results revealed the genomic determinants of T. evansi, which encoded specific biological characteristics that distinguished them from other related trypanosome species.
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http://dx.doi.org/10.1007/s11427-018-9473-8DOI Listing
March 2019

Genotype Determines Tim-3 Expression Levels in Splenic and Circulatory T Cells in Mice.

Front Microbiol 2018 4;9:2967. Epub 2018 Dec 4.

Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.

is an obligatory intracellular parasite that causes a common infection in many warm-blooded animals. During infection, the host's immune system plays an important role in confining the dissemination of the parasites in the hosts. T cell immunoglobulin- and mucin domain-containing molecule 3 (Tim-3) has been characterized as an important regulator in cell-mediated immune responses in various infections. Here, we compared Tim-3 expression on splenic and circulatory T, B cells and a few cytokines in the sera of mice infected with the more virulent type I (RH) vs. the low virulent type II (ME49) strain. Tim-3 expression on the splenic and circulatory T cells of mice infected with (RH strain) was higher than that in mice infected with (ME49 strain). infection reduced the proportion of splenic helper T cells (Th) and cytotoxic T cells (Tc) and increased Tim-3 expression. Further, serum levels of interleukin (IL)-2, interferon γ, tumor necrosis factor (TNF)-α, IL-12p70, IL-22, IL-17A, and IL-5 increased significantly after infection. Mice infected with (ME49 strain) showed higher levels of TNF-α, IL-17A, IL-12p70, and IL-22 than that infected by the RH strain. Our study revealed that strains may have their inherent ability in triggering different host immune responses, which may explain the clinical variation in diseases severity after infection.
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http://dx.doi.org/10.3389/fmicb.2018.02967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288189PMC
December 2018

Expression and functional analysis of the TatD-like DNase of Plasmodium knowlesi.

Parasit Vectors 2018 Dec 12;11(1):629. Epub 2018 Dec 12.

Key Laboratory of Zoonosis, Shenyang Agricultural University, Dongling Road 120, Shenyang, 110866, China.

Background: In recent years, human infection by the simian malaria parasite Plasmodium knowlesi has increased in Southeast Asia, leading to growing concerns regarding the cross-species spread of the parasite. Consequently, a deeper understanding of the biology of P. knowlesi is necessary in order to develop tools for control of the emerging disease. TatD-like DNase expressed at the surface of P. falciparum has recently been shown to counteract host innate immunity and is thus a potential malaria vaccine candidate.

Methods: The expression of the TatD DNase of P. knowlesi (PkTatD) was confirmed by both Western-blot and immunofluorescent assay. The DNA catalytic function of the PkTatD was confirmed by digestion of DNA with the recombinant PkTatD protein in the presence of various irons.

Results: In the present study, we investigated the expression of the homologous DNase in P. knowlesi. The expression of TatD-like DNase in P. knowslesi (PkTatD) was verified by Western blot and indirect immunofluorescence assays. Like that of the P. falciparum parasite, PkTatD was also found to be located on the surface of erythrocytes infected by the parasites. Biochemical analysis indicated that PkTatD can hydrolyze DNA and this activity is magnesium-dependent.

Conclusions: We identified that PkTatD expressed on the surface of P. knowlesi-infected RBCs is a Mg-dependent DNase and exhibits a stronger hydrolytic capacity than TatD from P. falciparum. The data support our previous findings that TatD-like DNase is a unanimously expressed virulence factor of Plasmodium parasites.
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http://dx.doi.org/10.1186/s13071-018-3251-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291984PMC
December 2018

Inclusion of membrane-anchored LTB or flagellin protein in H5N1 virus-like particles enhances protective responses following intramuscular and oral immunization of mice.

Vaccine 2018 09 30;36(40):5990-5998. Epub 2018 Aug 30.

Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, Jilin Province, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province, China; Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, Jilin Province, China. Electronic address:

We previously demonstrated that intramuscular immunization with virus-like particles (VLPs) composed of the haemagglutinin (HA), neuraminidase (NA), and matrix (M1) proteins of A/meerkat/Shanghai/SH-1/2012 (clade 2.3.2.1) protected mice from lethal challenge with viruses from other H5 HPAI clades. The inclusion of additional proteins that can serve as immunological adjuvants in VLPs may enhance adaptive immune responses following vaccination, and oral vaccines may represent the safest choice. Here, we report the generation of H5N1 VLPs composed of the viral HA, NA, and M1 proteins and membrane-anchored forms of the Escherichia coli heat-labile enterotoxin B subunit protein (LTB) or the Toll-like receptor 5 ligand flagellin (Flic). Mice intramuscularly or orally immunized with VLPs containing LTB or Flic generated greater humoural and cellular immune responses than those administered H5N1 VLPs without LTB or Flic. Intramuscular immunization with VLPs protected mice from lethal challenge with homologous or heterologous H5N1 viruses irrespective of whether the VLPs additionally included LTB or Flic. In contrast, oral immunization of mice with LTB- or Flic-VLPs conferred substantial protection against lethal challenge with both homologous and heterologous H5N1 influenza viruses, whereas mice immunized orally with VLPs lacking LTB and Flic universally succumbed to infection. Mice immunized orally with LTB- or Flic-VLPs showed 10-fold higher virus-specific IgG titres than mice immunized with H5N1-VLPs lacking LTB or Flic. Collectively, these results indicate that the inclusion of immunostimulatory proteins, such as LTB and Flic, in VLP-based vaccines may represent a promising new approach for the control of current H5N1 HPAI outbreaks by eliciting higher humoural and cellular immune responses and conferring improved cross-clade protection.
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http://dx.doi.org/10.1016/j.vaccine.2018.08.053DOI Listing
September 2018

Identification and characterization of DNA endonucleases in Plasmodium falciparum 3D7 clone.

Malar J 2018 Jun 18;17(1):232. Epub 2018 Jun 18.

Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, People's Republic of China.

Background: Plasmodium falciparum is the most virulent parasite of the five Plasmodium species that cause human malaria, and biological analysis of the parasite is critical for the development of novel strategies for disease control. DNA endonucleases are important for maintaining the biological activity, gene stability of the parasite and interaction with host immune systems. In this study, ten sequences of DNA endonucleases were found in the genome of P. falciparum 3D7 clone, seven of them were predicted to contain an endonuclease/exonuclease/phosphatase (IPR005135) domain which plays an important role in DNA catalytic activity. The seven DNA endonucleases of P. falciparum were systematically investigated.

Methods: Plasmodium falciparum 3D7 clone was cultured in human O RBCs, RNA was extracted at 8, 16, 24, 32, 40, and 48 h post invasion and real-time quantitative PCR was carried out to analyse the transcription of the seven DNA endonuclease genes in asexual stages. Immunofluorescence assay was carried out to confirm the location of the encoded proteins expressed in the erythrocytic stages. Finally, the catalytic activity of the DNA nucleases were tested.

Results: Of the seven proteins analysed, two proteins were not soluble. Fragments derived from the rest five endonuclease sequences were successfully expressed as soluble proteins, and which were used to generate antisera for protein localization. The proteins were all located in the nucleus at ring and trophozoite stages. While at schizont stage, proteins encoded by PF3D7_1238600, PF3D7_0107200 and PF3D7_0319200 were in the punctuated forms in the parasite most likely around nuclei of the merozoites. But the proteins encoded by PF3D7_0305600 and PF3D7_1363500 were distributed around the infected erythrocyte membrane. The enzymatic activity of the recombinant GST-PF3D7_1238600 was very efficient without divalent iron, while the activity of the rest four enzymes was iron dependent. Further, divalent irons did not show any specific enhancement on the activity of GST-PF3D7_1238600, but the activity of GST-PF3D7_0107200, GST-PF3D7_1363500 and GST-PF3D7_0319200 were Cu dependent. The activity of GST-PF3D7_0305600 was dependent on Mg and Mn. Except GST-PF3D7_1363500, four of the GST tagged recombinant proteins hydrolysed the supercoiled circular plasmid DNA with or without divalent metal ions. The GST-PF3D7_1363500 protein only changed the supercoiled circular plasmid DNA into nicked plasmids, even with Cu.

Conclusions: Fragments derived from five of the endonuclease sequences of P. falciparum 3D7 clone were successfully expressed. The proteins displayed diverse cell distribution, biochemical and enzymatic activities, which indicated that they carried different biological function in the development of the parasite in the erythrocytes. The DNA repair and DNA degradation capacity of the DNA endonucleases in the biology of the parasite remained further studied.
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http://dx.doi.org/10.1186/s12936-018-2388-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6006590PMC
June 2018

Plasmodium TatD-Like DNase Antibodies Blocked Parasite Development in the Mosquito Gut.

Front Microbiol 2018 18;9:1023. Epub 2018 May 18.

Key Laboratory of Zoonosis, Jilin University, Changchun, China.

The TatD-like DNase of species has previously been characterized as a conserved antigen that plays an important role in immune evasion. Here, we found that TatD-like DNase is expressed, apart from the erythrocytic stage, throughout the developmental stages of the parasite in the mosquito vector. Antibodies to the molecule significantly blocked parasites development and transition in the mosquito gut. Further, mice immunized with recombinant TatD-like DNase showed significant resistance to parasite challenge. The antigenicity of the TatD-like antigen in combination with various adjuvants, including Freund's adjuvants, Montanide ISA 51 and 61, Alhydrogel (aluminum hydroxide), and levamisole was investigated. It was found that immunization of the recombinant TatD-like DNase in combination with Montanide ISA 51 induced strong responses that showed significant protection against parasite challenge in a mouse model. The data further support that TatD-like DNase is a functionally important molecule in the whole development cycle of the malaria parasites and a candidate for malaria vaccine development.
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http://dx.doi.org/10.3389/fmicb.2018.01023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5968200PMC
May 2018

Characterization of the Catalytic Subunits of the RNA Exosome-like Complex in Plasmodium falciparum.

J Eukaryot Microbiol 2018 11 7;65(6):843-853. Epub 2018 May 7.

Key Laboratory of Zoonosis, Shenyang Agricultural University, 120 Dongling Road, Shenyang, China.

The eukaryotic ribonucleic acid (RNA) exosome is a versatile multiribonuclease complex that mediates the processing, surveillance, and degradation of virtually all classes of RNA in both the nucleus and cytoplasm. The complex, composed of 10 to 11 subunits, has been widely described in many organisms. Bioinformatic analyses revealed that there may be also an exosome-like complex in Plasmodium falciparum, a parasite of great importance in public health, with eight predicted subunits having high sequence similarity to their counterparts in yeast and human. In this work, the putative RNA catalytic components, designated as PfRrp4, PfRrp41, PfDis3, and PfRrp6, were identified and systematically analyzed. Quantitative polymerase chain reaction (QPCR) analyses suggested that all of them were transcribed steadily throughout the asexual stage. The expression of these proteins was determined by Western blot, and their localization narrowed to the cytoplasm of the parasite by indirect immunofluorescence. The recombinant proteins of PfRrp41, PfDis3, and PfRrp6 exhibited catalytic activity for single-stranded RNA (ssRNA), whereas PfRrp4 showed no processing activity of both ssRNA and dsRNA. The identification of these putative components of the RNA exosome complex opens up new perspectives for a deep understanding of RNA metabolism in the malarial parasite P. falciparum.
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http://dx.doi.org/10.1111/jeu.12625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6282785PMC
November 2018

Intramuscular and intranasal immunization with an H7N9 influenza virus-like particle vaccine protects mice against lethal influenza virus challenge.

Int Immunopharmacol 2018 May 20;58:109-116. Epub 2018 Mar 20.

Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun 130122, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225000, China; Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China. Electronic address:

The H7N9 influenza virus epidemic has been associated with a high mortality rate in China. Therefore, to prevent the H7N9 virus from causing further damage, developing a safe and effective vaccine is necessary. In this study, a vaccine candidate consisting of virus-like particles (VLPs) based on H7N9 A/Shanghai/2/2013 and containing hemagglutinin (HA), neuraminidase (NA), and matrix protein (M1) was successfully produced using a baculovirus (BV) expression system. Immunization experiments showed that strong humoral and cellular immune responses could be induced by the developed VLPs when administered via either the intramuscular (IM) or intranasal (IN) immunization routes. Notably, VLPs administered via both immunization routes provided 100% protection against lethal infection caused by the H7N9 virus. The IN immunization with 40μg of H7N9 VLPs induced strong lung IgA and lung tissue resident memory (TRM) cell-mediated local immune responses. These results provide evidence for the development of an effective preventive vaccine against the H7N9 virus based on VLPs administered through both the IM and IN immunization routes.
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http://dx.doi.org/10.1016/j.intimp.2017.12.020DOI Listing
May 2018

Seroepidemiology and Risk Factors of Infection among the Newly Enrolled Undergraduates and Postgraduate Students in China.

Front Microbiol 2017 26;8:2092. Epub 2017 Oct 26.

Key Laboratory of Zoonosis of Liaoning Province, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.

is an obligate intracellular zoonotic parasite, infecting warm-blood animals including humans. Previous serological surveys of infection have focused on people of different occupations and special groups, such as slaughterhouse workers, AIDS patients and pregnant women. To investigate the potential impact of infection on the health of young students, the prevalence of infection and associated risk factors among the newly enrolled undergraduates and postgraduate students were investigated. A total of 3,569 newly enrolled students (age range: 15- to 37-years-old, median 26 years) from various regions of China were recruited in this study. The serum samples were tested for the presence of specific IgG by the modified agglutination test (MAT). Questionnaires were used to collect information on risk factors for infection. Sixty-five (1.82%) out of 3,569 participants were seropositive for IgG antibodies to by MAT (titer≥1:20). Four variables were found to be positively associated with infection, including primary geographical location, living in rural areas, gardening or agriculture, and drinking unboiled water by the univariate logistic regression, and only gardening or agriculture was the independent risk factor for positivity by using multivariate logistic regression in this study, which may provide information to guide future research and control policies.
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http://dx.doi.org/10.3389/fmicb.2017.02092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662622PMC
October 2017

Nutritional value, chemical composition and antioxidant activity of three Tuber species from China.

AMB Express 2017 Dec 26;7(1):136. Epub 2017 Jun 26.

College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China.

Nutritional value, chemical composition and antioxidant activity of the traditional edible truffles Tuber latisporum, T. subglobosum and T. pseudohimalayense, from China were evaluated. Powder formulations of the three truffles revealed the presence of essential nutrients, such as proteins, carbohydrates and unsaturated fatty acids, and T. latisporum presented the highest contents of total sugar (50.10 g/100 g) and monounsaturated fatty acids (265.19 mg/100 g dw); T. pseudohimalayense showed the highest content of polyunsaturated fatty acids (367.98 mg/100 g dw). They all presented a low fat content but high contents of proteins and unsaturated fatty acid, which is beneficial to human health. The methanol extract from T. pseudohimalayense showed a high radicals scavenging activity and the highest content of total phenols (735.01 mg/100 g dw); T. subglobosum presented the highest content of flavonoids (1355.43 mg/100 g dw). All these extracts could be used as potential antioxidant sources to prevent diseases related to oxidative damage.
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http://dx.doi.org/10.1186/s13568-017-0431-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484652PMC
December 2017

The innate immunity of guinea pigs against highly pathogenic avian influenza virus infection.

Oncotarget 2017 May;8(18):30422-30437

Key Laboratory of Jilin Province for Zoonosis Prevention and Control, The Military Veterinary Institute, Academy of Military Medical Science of PLA, Changchun, 130122, PR China.

H5N1 avian influenza viruses are a major pandemic concern. In contrast to the highly virulent phenotype of H5N1 in humans and many animal models, guinea pigs do not typically display signs of severe disease in response to H5N1 virus infection. Here, proteomic and transcriptional profiling were applied to identify host factors that account for the observed attenuation of A/Tiger/Harbin/01/2002 (H5N1) virulence in guinea pigs. RIG-I and numerous interferon stimulated genes were among host proteins with altered expression in guinea pig lungs during H5N1 infection. Overexpression of RIG-I or the RIG-I adaptor protein MAVS in guinea pig cell lines inhibited H5N1 replication. Endogenous GBP-1 expression was required for RIG-I mediated inhibition of viral replication upstream of the activity of MAVS. Furthermore, we show that guinea pig complement is involved in viral clearance, the regulation of inflammation, and cellular apoptosis during influenza virus infection of guinea pigs. This work uncovers features of the guinea pig innate immune response to influenza that may render guinea pigs resistant to highly pathogenic influenza viruses.
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http://dx.doi.org/10.18632/oncotarget.16503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5444753PMC
May 2017

Intranasal Immunization with Influenza Virus-Like Particles Containing Membrane-Anchored Cholera Toxin B or Ricin Toxin B Enhances Adaptive Immune Responses and Protection against an Antigenically Distinct Virus.

Viruses 2016 Apr 21;8(4):115. Epub 2016 Apr 21.

Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun 130122, China.

Vaccination is the most effective means to prevent influenza virus infection, although current approaches are associated with suboptimal efficacy. Here, we generated virus-like particles (VLPs) composed of the hemagglutinin (HA), neuraminidase (NA) and matrix protein (M1) of A/Changchun/01/2009 (H1N1) with or without either membrane-anchored cholera toxin B (CTB) or ricin toxin B (RTB) as molecular adjuvants. The intranasal immunization of mice with VLPs containing membrane-anchored CTB or RTB elicited stronger humoral and cellular immune responses when compared to mice immunized with VLPs alone. Administration of VLPs containing CTB or RTB significantly enhanced virus-specific systemic and mucosal antibody responses, hemagglutination inhibiting antibody titers, virus neutralizing antibody titers, and the frequency of virus-specific IFN-γ and IL-4 secreting splenocytes. VLPs with and without CTB or RTB conferred complete protection against lethal challenge with a mouse-adapted homologous virus. When challenged with an antigenically distinct H1N1 virus, all mice immunized with VLPs containing CTB or RTB survived whereas mice immunized with VLPs alone showed only partial protection (80% survival). Our results suggest that membrane-anchored CTB and RTB possess strong adjuvant properties when incorporated into an intranasally-delivered influenza VLP vaccine. Chimeric influenza VLPs containing CTB or RTB may represent promising vaccine candidates for improved immunological protection against homologous and antigenically distinct influenza viruses.
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http://dx.doi.org/10.3390/v8040115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4848608PMC
April 2016

Adaptation of H9N2 AIV in guinea pigs enables efficient transmission by direct contact and inefficient transmission by respiratory droplets.

Sci Rep 2015 Nov 10;5:15928. Epub 2015 Nov 10.

Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, China.

H9N2 avian influenza viruses circulate worldwide in poultry and have sporadically infected humans, raising concern whether H9N2 viruses have pandemic potential. Here, we use a guinea pig model to examine whether serial passage results in adaptive viral changes that confer a transmissible phenotype to a wild-type H9N2 virus. After nine serial passages of an H9N2 virus through guinea pigs, productive transmission by direct contact occurred in 2/3 guinea pig pairs. The efficiency of transmission by direct contact increased following the fifteenth passage and occurred in 3/3 guinea pig pairs. In contrast, airborne transmission of the passaged virus was less efficient and occurred in 1/6 guinea pig pairs and 0/6 ferret pairs after the fifteenth passage. Three amino acid substitutions, HA1-Q227P, HA2-D46E, and NP-E434K, were sufficient for contact transmission in guinea pigs (2/3 pairs). The two HA amino acid substitutions enhanced receptor binding to α2,3-linked sialic acid receptors. Additionally, the HA2-D46E substitution increased virus thermostability whereas the NP-E434K mutation enhanced viral RNA polymerase activity in vitro. Our findings suggest that adaptive changes that enhance viral receptor binding, thermostability, and replicative capacity in mammalian cells can collectively enhance the transmissibility of H9N2 AIVs by direct contact in the guinea pig model.
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http://dx.doi.org/10.1038/srep15928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639850PMC
November 2015

Newly Emergent Highly Pathogenic H5N9 Subtype Avian Influenza A Virus.

J Virol 2015 Sep 17;89(17):8806-15. Epub 2015 Jun 17.

Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China

Unlabelled: The novel H7N9 avian influenza virus (AIV) was demonstrated to cause severe human respiratory infections in China. Here, we examined poultry specimens from live bird markets linked to human H7N9 infection in Hangzhou, China. Metagenomic sequencing revealed mixed subtypes (H5, H7, H9, N1, N2, and N9). Subsequently, AIV subtypes H5N9, H7N9, and H9N2 were isolated. Evolutionary analysis showed that the hemagglutinin gene of the novel H5N9 virus originated from A/Muscovy duck/Vietnam/LBM227/2012 (H5N1), which belongs to clade 2.3.2.1. The neuraminidase gene of the novel H5N9 virus originated from human-infective A/Hangzhou/1/2013 (H7N9). The six internal genes were similar to those of other H5N1, H7N9, and H9N2 virus strains. The virus harbored the PQRERRRKR/GL motif characteristic of highly pathogenic AIVs at the HA cleavage site. Receptor-binding experiments demonstrated that the virus binds α-2,3 sialic acid but not α-2,6 sialic acid. Identically, pathogenicity experiments also showed that the virus caused low mortality rates in mice. This newly isolated H5N9 virus is a highly pathogenic reassortant virus originating from H5N1, H7N9, and H9N2 subtypes. Live bird markets represent a potential transmission risk to public health and the poultry industry.

Importance: This investigation confirms that the novel H5N9 subtype avian influenza A virus is a reassortant strain originating from H5N1, H7N9, and H9N2 subtypes and is totally different from the H5N9 viruses reported before. The novel H5N9 virus acquired a highly pathogenic H5 gene and an N9 gene from human-infecting subtype H7N9 but caused low mortality rates in mice. Whether this novel H5N9 virus will cause human infections from its avian host and become a pandemic subtype is not known yet. It is therefore imperative to assess the risk of emergence of this novel reassortant virus with potential transmissibility to public health.
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http://dx.doi.org/10.1128/JVI.00653-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4524050PMC
September 2015

Rapid emergence of a PB2-E627K substitution confers a virulent phenotype to an H9N2 avian influenza virus during adoption in mice.

Arch Virol 2015 May 19;160(5):1267-77. Epub 2015 Mar 19.

Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150000, Heilongjiang, China.

The worldwide circulation of H9N2 avian influenza virus in poultry, the greater than 2.3 % positive rate for anti-H9 antibodies in poultry-exposed workers, and several reports of human infection indicate that H9N2 virus is a potential threat to human health. Here, we found three mutations that conferred high virulence to H9N2 virus in mice after four passages. The PB2-E627K substitution rapidly appeared at the second passage and played a decisive role in virulence. Polymerase complexes possessing PB2-E627K displayed 16.1-fold higher viral polymerase activity when compared to the wild-type virus, which may account for enhanced virulence of this virus. The other two substitutions (HA-N313D and HA-N496S) enhanced binding to both α2,3-linked and α2,6-linked sialic acid receptors; however, the HA-N313D and N496S substitutions alone decreased the virulence of mouse-adapted virus. Furthermore, this mouse-adapted virus was still not transmissible among guinea pigs by direct contact (0/3 pairs). Our findings show that adaption in mice enhanced the viral polymerase activity and receptor-binding ability, which resulted in a virulent phenotype in mice but not a transmissible phenotype in guinea pigs, indicating that host factors play an important role in adaptive evolution of influenza in new hosts.
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http://dx.doi.org/10.1007/s00705-015-2383-5DOI Listing
May 2015

Lowly pathogenic avian influenza (H9N2) infection in Plateau pika (Ochotona curzoniae), Qinghai Lake, China.

Vet Microbiol 2014 Sep 12;173(1-2):132-5. Epub 2014 Jul 12.

Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, People's Republic of China; Military Veterinary Research Institute of Academy of Military Medical Sciences, Changchun, People's Republic of China. Electronic address:

Avian influenza viruses (AIVs) are globally important contagions. Several domestic mammals can be infected with AIVs and may play important roles in the adaptation and transmission of these viruses in mammals, although the roles of wild mammals in the natural ecology of AIVs are not yet clear. Here, we performed a serological survey of apparently healthy Plateau pikas at Qinghai Lake in China to assess the prevalence of exposure to AIVs. Ninety-two of 293 (31%) of wild Plateau pikas possessed serum antibodies against a lowly pathogenic avian influenza (LPAI) H9N2 virus. Experimental inoculation of Plateau pikas with a LPAI H9N2 virus resulted in productive viral replication in respiratory tissues without prior adaptation. Our findings suggest that Plateau pikas represent a natural mammalian host to H9N2 AIVs and may play a role in the ongoing circulation of H9N2 viruses at Qinghai Lake in China. Surveillance for AIV infection in Plateau pika populations and other mammals that have close contact with the Plateau pikas should be considered.
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http://dx.doi.org/10.1016/j.vetmic.2014.07.002DOI Listing
September 2014
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