Molecular Characterization and Function of the Nogo-66 Receptor (NgR1) Gene in the Chinese Tree Shrew.

BACKGROUND: Nogo-66 receptor (NgR1) is a glycosylphosphatidylinositol-linked cell surface receptor with high affinity for Nogo-66. The binding of Nogo-66 to NgR1 plays a key role in inhibiting neurite growth, limiting synaptic plasticity and mediating Mammalian Reovirus (MRV) infection. The Chinese tree shrew (Tupaia belangeri chinensis) is, a new and valuable experimental animal that is widely used in biomedical research. Although susceptible to MRV, little is known about tree shrew NgR1 and its role in MRV infection. METHODS: In this study, we cloned NgR1 form the Chinese tree shrew by RACE technology and analyzed its characteristics, spatial structure and its tissue expression. We also examined the expression pattern of NgR1 in the response of tree shrew primary nerve cells (tNC) to MRV1/TS/2011 infection. RESULTS: Tree shrew NgR1 was found to have a closer relationship to human NgR1 (90.34%) than to mouse NgR1. Similar to the protein structure of human NgR1, the tree shrew NgR1 has the same leucine-rich repeat (LRR) domain structure that is capped by C-terminal and N-terminal cysteine-rich modules. The tree shrew NgR1 mRNAs were predominantly detected in the central nervous system (CNS), and tree shrew NgR1 can mediate infection by MRV1/TS/2011. CONCLUSIONS: Taken together, these results help to elucidate the function of NgR1 and provide a basis for using the tree shrew as an animal model for studies of the nervous system and infectious diseases.

Identification of SEC14 like lipid binding 2(SEC14L2) sequence and expression profiles in the Chinese tree shrew (Tupaia belangeri chinensis).

BACKGROUND: The product of the SEC14L2 (SEC14 Like Lipid Binding 2) gene belongs to a family of lipid-binding proteins including Sec14p, alpha-tocopherol transfer protein, and cellular retinol-binding protein. SEC14L2 expression enables replication of clinical hepatitis C virus (HCV) isolates in several hepatoma cell lines, and mutations in SEC14L2 may enhance HCV replication in vitro. The Chinese tree shrew (Tupaia belangeri chinensis) is a potential animal model for studying HCV replication, however, the cDNA sequence, protein structure, and expression of the Chinese tree shrew SEC14L2 gene have yet to be characterized. METHODS AND RESULTS: In the present study, we cloned the full-length cDNA sequence of the SEC14L2 in the Chinese tree shrew by using rapid amplification of cDNA ends technology. This led us to determine that, this is 2539 base pairs (bp) in length, the open reading frame sequence is 1212 bp, and encodes 403 amino acids. Following this, we constructed a phylogenetic tree based on SEC14L2 molecules from various species and compared SEC14L2 amino acid sequence with other species. This analysis indicated that the Chinese tree shrew SEC14L2 protein (tsSEC14L2) has 96.28% amino acid similarity to the human protein, and is more closely related to the human protein than either mouse or rat protein. The Chinese tree shrew SEC14L2 mRNA was detected in all tissues, and showed highest expression levels in the pancreas, small intestine and trachea, however the tsSEC14L2 protein abundance was highest in the liver and small intestine. CONCLUSION: The Chinese tree shrew SEC14L2 gene was closer in evolutionary relation to humans and non-human primates and expression of the tsSEC14L2 protein was highest in the liver and small intestine. These results may provide useful information for tsSEC14L2 function in HCV infection.

Molecular cloning and characterization of NPC1L1 in the Chinese tree shrew (Tupaia belangeri chinensis).

BACKGROUND: The Niemann-Pick C1-Like 1 protein, a multi-transmembrane domain molecule, is critical for intestinal cholesterol absorption, and is the entry factor for hepatitis C virus (HCV). The Chinese tree shrew (Tupaia belangeri chinensis) is closer to primates in terms of genetic evolution than rodents. Previous studies indicated that the tree shrew was suitable for HCV research; however, little is known about tree shrew NPC1L1. METHODS AND RESULTS: TsNPC1L1 cDNA was amplified by rapid amplification of cDNA ends (RACE) technology. The cDNA sequence, its encoded protein structure, and expression profile were analyzed. Results indicated that the tsNPC1L1 mRNA is 4948 bp in length and encodes a 1326 amino acid protein. TsNPC1L1 possesses 84.97% identity in homology to human NPC1L1 which is higher than both mouse (80.37%) and rat (81.80%). The protein structure was also similar to human with 13 conserved transmembrane helices, and a sterol-sensing domain (SSD). Like human NPC1L1, the tsNPC1L1 mRNA transcript is highly expressed in small intestine, but it was also well-expressed in the lung and pancreas of the tree shrew. CONCLUSION: The homology of tree shrew NPC1L1 was closer to human than that of rodent NPC1L1. The expression of tsNPC1L1 was the highest in small intestine, and was detectable in lung and pancreas. These results may be useful in the study of tsNPC1L1 function in cholesterol absorption and HCV infection.

Zika Virus Infection in Tupaia belangeri Causes Dermatological Manifestations and Confers Protection against Secondary Infection.

Animal models of Zika virus (ZIKV) infection have recently been established in mice, guinea pigs, and nonhuman primates. Tree shrews (Tupaia belangeri) are an emerging experimental animal in biomedical applications, but their susceptibility to ZIKV infection has not been explored. In the present study, we show that subcutaneous inoculation of ZIKV led to rapid viremia and viral secretion in saliva, as well as to typical dermatological manifestations characterized by massive diffuse skin rash on the trunk. Global transcriptomic sequencing of peripheral blood mononuclear cells isolated from ZIKV-infected animals revealed systematic gene expression changes related to the inflammatory response and dermatological manifestations. Importantly, ZIKV infection readily triggered the production of high-titer neutralizing antibodies, thus preventing secondary homologous infection in tree shrews. However, neonatal tree shrews succumbed to ZIKV challenge upon intracerebral infection. The tree shrew model described here recapitulates the most common dermatological manifestations observed in ZIKV-infected patients and may greatly facilitate the elucidation of ZIKV pathogenesis and the development of novel vaccines and therapeutics.IMPORTANCE The reemergence of Zika virus (ZIKV) has caused a global public health crisis since 2016, and there are currently no vaccines or antiviral drugs to prevent or treat ZIKV infection. However, considerable advances have been made in understanding the biology and pathogenesis of ZIKV infection. In particular, various animal models have been successfully established to mimic ZIKV infection and its associated neurological diseases and to evaluate potential countermeasures. However, the clinical symptoms in these mouse and nonhuman primate models are different from the common clinical manifestations seen in human ZIKV patients; in particular, dermatological manifestations are rarely recapitulated in these animal models. Here, we developed a new animal model of ZIKV infection in tree shrews, a rat-sized, primate-related mammal. In vitro and in vivo characterization of ZIKV infection in tree shrews established a direct link between ZIKV infection and the immune responses and dermatological manifestations. The tree shrew model described here, as well as other available animal models, provides a valuable platform to study ZIKV pathogenesis and to evaluate vaccines and therapeutics.

Response of the gut microbiota during the Clostridioides difficile infection in tree shrews mimics those in humans.

BACKGROUND: Clostridioides difficile is a major cause of antibiotic associated diarrhea. Several animal models are used to study C. difficile infection (CDI). The tree shrew has recently been developed as a model of primate processes. C. difficile infection has not been examined in tree shrews. We infected tree shrews with hyper-virulent C. difficile strains and examined the alterations in gut microbiota using 16S rRNA gene sequencing. RESULTS: C. difficile colonized the gastrointestinal tract of tree shrew and caused diarrhea and weight loss. Histopathologic examination indicated structures and mucosal cell destruction in ileal and colonic tissues. The gut microbial community was highly diversity before infection and was dominated by Firmicutes, Fusobacteria, Bacteroidetes, and Proteobacteria. Antibiotic administration decreased the diversity of the gut microbiota and led to an outgrowth of Lactobacillus. The relative abundance of Proteobacteria, Gammaproteobacteria, Enterobacteriales, Lachnospiraceae, Enterobacteriaceae, Escherichia, Blautia, and Tyzzerella increased following C. difficile infection. These taxa could be biomarkers for C. difficile colonization. CONCLUSIONS: In general, the disease symptoms, histopathology, and gut microbiota changes following C. difficile infection in tree shrews were similar to those observed in humans.

Tree shrew bone marrow-derived mesenchymal stem cells express CD81, OCLN, and miR-122, facilitating the entire hepatitis C virus life cycle.

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and associated cirrhosis, and hepatocellular carcinoma worldwide. At present, there is no prophylactic vaccine against HCV due to the lack of in vivo and in vitro model systems. Although most recombinants of all major HCV genotypes replicate in Huh-7 cell line and derivatives, these cells are human hepatoma-derived cell line. Therefore, the development of un-tumor-derived cell systems facilitating the entire HCV life cycle is urgently needed. In this study, we aimed to establish a novel tree shrew-derived bone marrow-derived mesenchymal stem cell (BM-MSC) system to reconstruct the HCV life cycle. We transduction cluster of differentiation 81 (CD81), occludin (OCLN), and microRNA-122 (miR-122) into BM-MSCs, then used a well-established HCV, produced from the J6/JFH1-Huh7.5.1 culture system, to infect the cells. We observed that BM-MSCs transduction with CD81/OCLN or CD81/OCLN/miR-122 support HCV RNA replication and infectious virus production. We also found that the addition of exogenous vascular endothelial growth factor (VEGF) can enhance HCV infectivity in BM-MSCs, with HCV virus load up to 105 copies/mL. In conclusion, we identified the minimum essential factors required for HCV replication in tree shrew-derived nonhuman nonhepatic BM-MSCs. Further, we identified that exogenous addition of VEGF, and exogenous expression of CD81, OCLN, and miR-122, facilitates efficient viral replication and production of infectious particles. Our results describe a novel cell system capable of supporting the entire HCV life cycle, which may provide an essential tool for anti-HCV drug discovery, vaccine development, and study of pathogenesis.

Isolation and identification of two new strains of mammalian orthoreovirus from Chinese tree shrews.

Chinese tree shrews have been used extensively in studies of different types of cancer and for the modeling of viral infections. In the present study, we report the isolation and characterization of two strains of mammalian orthoreovirus (MRV), MRV1/TS/2011 and MRV3/TS/2012, which were isolated from the feces of tree shrews in Yunnan, China. These two strains of MRV were isolated and cultured in both primary tree shrew intestinal epithelial cells (pTIECs) and primary tree shrew alveolar epithelial cells (pTAECs). A neutralization test using immunofluorescence was employed to determine the subtype of each isolate. Viral RNA was extracted and analyzed by polyacrylamide gel electrophoresis (PAGE), and the sequence was determined by next-generation sequencing for construction of a phylogenetic tree and analysis of gene polymorphism. Electron microscopy examination revealed the presence of virus particles with the typical morphological characteristics of MRV. Serotype analysis showed that strain MRV1/TS/2011 was of type I and strain MRV3/TS/2012 was of type III. A sequence comparison showed that the isolates were 25.4% identical in the S1 gene.

The characteristics of gut microbiota and commensal Enterobacteriaceae isolates in tree shrew (Tupaia belangeri).

BACKGROUND: Tree shrew is a novel laboratory animal with specific characters for human disease researches in recent years. However, little is known about its characteristics of gut microbial community and intestinal commensal bacteria. In this study, 16S rRNA sequencing method was used to illustrate the gut microbiota structure and commensal Enterobacteriaceae bacteria were isolated to demonstrate their features. RESULTS: The results showed Epsilonbacteraeota (30%), Proteobacteria (25%), Firmicutes (19%), Fusobacteria (13%), and Bacteroidetes (8%) were the most abundant phyla in the gut of tree shrew. Campylobacteria, Campylobacterales, Helicobacteraceae and Helicobacter were the predominant abundance for class, order, family and genus levels respectively. The alpha diversity analysis showed statistical significance (P < 0.05) for operational taxonomic units (OTUs), the richness estimates, and diversity indices for age groups of tree shrew. Beta diversity revealed the significant difference (P < 0.05) between age groups, which showed high abundance of Epsilonbacteraeota and Spirochaetes in infant group, Proteobacteria in young group, Fusobacteria in middle group, and Firmicutes in senile group. The diversity of microbial community was increased followed by the aging process of this animal. 16S rRNA gene functional prediction indicated that highly hot spots for infectious diseases, and neurodegenerative diseases in low age group of tree shrew (infant and young). The most isolated commensal Enterobacteriaceae bacteria from tree shrew were Proteus spp. (67%) and Escherichia coli (25%). Among these strains, the antibiotic resistant isolates were commonly found, and pulsed-field gel electrophoresis (PFGE) results of Proteus spp. indicated a high degree of similarity between isolates in the same age group, which was not observed for other bacteria. CONCLUSIONS: In general, this study made understandings of the gut community structure and diversity of tree shrew.

Molecular characteristics of Staphylococcus aureus isolates from food surveillance in southwest China.

BACKGROUND: Staphylococcal food poisoning (SFP) is one of the most common food-borne diseases in the world. Pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and spa typing methods were used to characterize Staphylococcus aureus isolates from food surveillance during 2013-2015 in southwest China, and Staphylococcal cassette chromosome mec (SCCmec) typing was used for methicillin-resistant S. aureus (MRSA). Isolates were also examined for their antibiotic resistance and carriage of virulence genes. RESULTS: Isolation rate of S. aureus was 2.60% during the three years' surveillance and 29.50% of them were MRSA. All the S. aureus had hla genes (100%), 14.34% of the strains had tst, and 16.73% had PVL. 163 PFGE-SmaI patterns, 41 ST types and 36 spa types were obtained for all the S. aureus. Among them, ST6-t701 (13.15%), ST7-t091 (12.75%), ST59-t437 (9.96%) and ST5-t002 (7.57%) were the prevalent genotypes. Most of MRSA in this study belonged to SCCmec IV and V, accounted for 74.32% and 20.27% respectively. ST6-SCCmec IV-t701 (36.50%) was the most prevalent clone among isolates from food, followed by ST59-SCCmec V-t437 (20.30%), ST5-SCCmec IV-t002 (12.20%) and ST59-SCCmec IV-t437 (12.20%). Some strains had the identical PFGE patterns, ST and spa types with isolates from patients. CONCLUSIONS: S. aureus isolated from food in southwest China displayed heterogeneity. Isolates had the same genotype profiles with isolates from patients, indicating high homology.

Tree shrew, a potential animal model for hepatitis C, supports the infection and replication of HCV in vitro and in vivo.

The tree shrew (Tupaia belangeri chinensis), a small animal widely distributed in Southeast Asia and southwest China, has the potential to be developed as an animal model for hepatitis C. To determine the susceptibility of the tree shrew to hepatitis C virus (HCV) infection in vitro and in vivo, a well-established HCV, produced from the J6/JFH1-Huh7.5.1 culture system, was used to infect cultured primary tupaia hepatocytes (PTHs) and tree shrews. The in vitro results showed that HCV genomic RNA and HCV-specific nonstructural protein 5A (NS5A) could be detected in the PTH cell culture from days 3-15 post-infection, although the viral load was lower than that observed in Huh7.5.1 cell culture. The occurrence of five sense mutations [S391A, G397A, L402F and M405T in the hypervariable region 1 (HVR1) of envelope glycoprotein 2 and I2750M in NS5B] suggested that HCV undergoes genetic evolution during culture. Fourteen of the 30 experimental tree shrews (46.7 %) were found to be infected, although the HCV viremia was intermittent in vivo. A positive test for HCV RNA in liver tissue provided stronger evidence for HCV infection and replication in tree shrews. The results of an immunohistochemistry assay also demonstrated the presence of four HCV-specific proteins (Core, E2, NS3/4 and NS5A) in the hepatocytes of infected tree shrews. The pathological changes observed in the liver tissue of infected tree shrews could be considered to be representative symptoms of mild hepatitis. These results revealed that the tree shrew can be used as an animal model supporting the infection and replication of HCV in vitro and in vivo.

In Vivo Confocal Microscopic Evaluation of Corneal Endothelial Dysfunction Induced by Phacoemulcification in Rhesus Monkey Models.

OBJECTIVE: To observe the characteristic morphological changes of corneal endothelial dysfunction induced by phacoemulcification in rhesus monkey models under confocal microscope. METHODS: The corneal endothelial dysfunction models were established by phacoemulcification power on the central corneal of 7 to 9 mm diameter in the right eyes of 4 rhesus monkeys (the modeling group). The left eyes of 4 rhesus monkeys were set as blank control group. The structural changes in different corneal layers were evaluated by slit lamp microscope and in vivo confocal microscope before surgery and 1, 2, 3, and 4 weeks after surgery. SPSS 19.0 software was applied to analyze data. Paired-t test was used to compare the number of nerve plexus in Bowman's layer and corneal endothelial cell density. Analysis of variance (ANOVA) was used to analyze corneal thickness. RESULTS: After phacoemulcification, the changes of cornea occurred gradually in the endothelial layer, stroma, Bowman's membrane, and basal epithelial layer. In the early stage, the interspace of corneal endothelial cells enlarged and few activated stromal cells were detected in the stroma. The cell morphology of stroma altered. The thickness of stroma increased. Two weeks after surgery, the nerve plexus in Bowman's layer decreased and edema of stroma and endothelial layer increased. Three weeks after surgery, the interspace of basal epithelial cells increased with a few Langerhans' cells infiltration and edema of stroma and endothelial layer increased. Four weeks after the surgery, a large amount of Langerhans' cells presented in basal epithelial layer. Only a few nerve lexus could be seen in Bowman's layer. The stroma and endothelial cells had severe edema. A large number of activated stromal cells could be found in stromal layer. Two weeks after the surgery, the number of nerve plexus in Bowman's layer (t=6.9192, P=0.002) and corneal endothelial cell density (t=7.8936, P<0.0001) in the modeling group were significantly lower than that in control group. Compared with corneal thickness in control group, it was significantly larger in the modeling group at 1 (t=28.31, P<0.0001), 2 (t=63.56, P<0.0001), 3 (t=123.22, P<0.0001), and 4 weeks (t=180.80, P<0.0001) after the surgery. CONCLUSIONS: The changes in corneal endothelial dysfunction induced by phacoemulcification in rhesus monkey models can be clearly shown under in vivo confocal microscope. Gradual increase of endothelial cells interspace, activated stromal cells, increase of Langerhans' cells, and decrease of plexus in Bowman's layer are the main changes.

Phylogenetic analysis of dengue virus reveals the high relatedness between imported and local strains during the 2013 dengue outbreak in Yunnan, China: a retrospective analysis.

BACKGROUND: An outbreak of dengue virus (DENV) occurred in Yunnan province. More than 2,000 individuals were infected from August to November 2013. In this study, we aimed to characterize the origin and prevalence of DENV in Dehong prefecture of Yunnan province using phylogenetic and evolutionary analyses of DENV strains collected from local patients and foreign travelers. METHODS: A total of 41 DENV-positive serum samples were randomly collected from travelers who entered China at Ruili port or local patients with dengue fever in Dehong prefecture of Yunnan province, China. The envelope (E) gene of DENV was amplified and sequenced. The distributions and evolutionary characteristics of different genotypes were elucidated by phylogenetic and Bayesian analyses. RESULTS: Phylogenetically, all of the 41 DENV-positive samples could be classified into genotype I (43.9%) of serotype DENV-1 and the Asian I genotype (56.1%) of serotype DENV-2. DENV strains derived from local patients and foreign travelers were scattered equally within these two clusters. Furthermore, the DENV strains from the two populations exhibited high relatedness based on evolutionary characteristics. CONCLUSIONS: These results suggested that imported and local DENV strains occurring during the dengue outbreak in 2013 were highly related. Additionally, these data may suggest that this dengue outbreak was caused by a newly imported infection from the neighboring country of Myanmar.

Bone-marrow mesenchymal stem cell transplantation to treat diabetic nephropathy in tree shrews.

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. We used a new DN model in tree shrews to validate the use of bone-marrow mesenchymal stem cell (BM-MSC) transplantation to treat DN. The DN tree shrew model was established by a high-sugar and high-fat diet and four injections of streptozotocin. 4',6-Diamidino-2-phenylindole labelled BM-MSCs were injected into tree shrews. The DN tree shrew model was successfully established. Blood glucose was significantly increased ( p < 0.01) during the entire experiment. DN tree shrews showed dyslipidemia, insulin resistance and increased 24-h proteinuria. At 21 days after BM-MSC transplantation, glucose and levels of triglycerides, total cholesterol and 24-h urine volume were lower than in tree shrews with DN alone ( p < 0.01) but were still higher than control values ( p < 0.01). Levels of creatinine and urea nitrogen as well as 24-h proteinuria were lower for DN tree shrews with BM-MSCs transplantation than DN alone ( p < 0.05). High-sugar and high-fat diet combined with STZ injection can induce a tree shrew model of DN. BM-MSCs injection can home to damaged kidneys and pancreas, for reduced 24-h proteinuria and improved insulin resistance.

Motor Function in MPTP-Treated Tree Shrews (Tupaia belangeri chinensis).

The tree shrew, a new experimental animal model, has been used to study a variety of diseases, especially diseases of the nervous system. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is the gold standard for toxin-based animal models of Parkinson's disease (PD) because MPTP treatment replicates almost all of the pathological hallmarks of PD. Therefore, in this study, the effects of MPTP on the motor function of the tree shrew were examined. After five daily injections of a 3 mg/kg dose of MPTP, the motor function of MPTP-injected tree shrews decreased significantly, and the classic Parkinsonian symptoms of action and resting tremor, bradykinesia, posture abnormalities, and gait instability were observed in most MPTP-injected tree shrews. HPLC results also showed significantly reduced striatal dopamine and 3,4-dihydroxyphenylacetic acid levels in tree shrews after MPTP injection. Increased oxidative stress levels are usually considered to be the cause of dopaminergic neuron depletion in the presence of MPTP and were observed in the substantia nigra of MPTP-treated tree shrews, as indicated by a significant reduction in superoxide dismutase and glutathione peroxidase activity and increased levels of malondialdehyde. In addition, elevated α-synuclein mRNA levels in the midbrain of MPTP-treated tree shrews were observed. Furthermore, MPTP-treated tree shrews showed the classic Parkinsonian symptoms at a lower MPTP dosage compared with other animal models. Thus, the MPTP-treated tree shrew may be a potential animal model for studying the pathogenesis of PD.

Transplantation of bone marrow mesenchymal stem cells for the treatment of type 2 diabetes in a macaque model.

Bone marrow mesenchymal stem cells (BMSCs) are self-renewing, multipotent cells that can migrate to pathological sites and thereby provide a new treatment in diabetic animals. Superparamagnetic iron oxide/4',6-diamidino-2-phenylindole (DAPI) double-labeled BMSCs were transplanted into the pancreatic artery of macaques to treat type 2 diabetes mellitus (T2DM). The treatment efficiency of BMSCs was also evaluated. After successful induction of the T2DM model, the treatment group received double-labeled BMSCs via the pancreatic artery. Six weeks after BMSC transplantation, the fasting blood glucose and blood lipid levels measured in the treatment group were significantly lower (p < 0.05) than in the model group, although they were not reduced to normal levels (p < 0.05). Additionally, the serum C-peptide levels were significantly increased (p < 0.05). An intravenous glucose tolerance test and C-peptide release test had significant changes to the area under the curve. Within 14 days of the transplantation of labeled cells, the pancreatic and kidney tissue of the treatment group emitted a negative signal that was visible on magnetic resonance imaging (MRI). Six weeks after transplantation, DAPI signals appeared in the pancreatic and kidney tissue, which indicates that the BMSCs were mainly distributed in damaged tissue. Labeled stem cells can be used to track migration and distribution in vivo by MRI. In conclusion, the transplantation of BMSCs for the treatment of T2DM is safe and effective.

miR-204-3p downregulates KRT16 and promotes corneal repair in tree shrew fungal keratitis model.

OBJECTIVES: Corneal repair is critical for the treatment and recovery of corneal injuries. However, the molecular mechanism underlying corneal repair remains unclear. METHODS: A tree shrew model of corneal fungal infection was established by injecting Fusarium solani into the corneal stroma to study the role of miR-204-3p in repairing corneal injury induced by fungal keratitis and to explore the potential mechanisms underlying the repair process. RESULTS: miR-204-3p expression was significantly downregulated, while KRT16 expression was significantly upregulated after F. solani infection in the cornea of tree shrews. Moreover, miR-204-3p injection promoted corneal injury repair post-infection, potentially by downregulating KRT16 expression. Results of a luciferase reporter gene assay showed that miR-204-3p had a targeted relationship with KRT16. KRT16 protein expression levels decreased after miR-204-3p injection into the cornea with fungal keratitis, reducing the degree of corneal injury. CONCLUSIONS: In this study, we report for the first time that miR-204-3p and KRT16 influence the repair of corneal injury. In addition, their effects on the repair of corneal injury were studied in a tree shrew model, providing an experimental basis for the study of pathogenesis of human fungal keratitis.

Molecularly cloned SHIV-CN97001: a replication-competent, R5 simian/human immunodeficiency virus containing env of a primary Chinese HIV-1 clade C isolate.

BACKGROUND: The increasing prevalence of human immunodeficiency virus type 1 (HIV-1) subtype C infection worldwide calls for efforts to develop a relevant animal model for evaluating AIDS candidate vaccines. In China, the prevalent HIV strains comprise a circulating recombinant form, BC (CRF07_BC), in which the envelope belongs to subtype C. METHODS: To evaluate potential AIDS vaccines targeting Chinese viral strains in non-human primate models, we constructed a simian/human immunodeficiency virus (SHIV) carrying most of the envelope sequence of a primary HIV-1 clade C strain isolated from an HIV-positive intravenous drug user from YunNan province in China. Furthermore, to determine whether in vivo adaptation would enhance the infectivity of SHIV-CN97001, the parental infectious strain was serially passaged through eight Chinese rhesus macaques. RESULTS: Infection of six Chinese rhesus macaques with SHIV-CN97001 resulted in a low level of viremia and no significant alteration in CD4+ T-lymphocyte counts. However, the hallmarks of SHIV infectivity developed gradually, as shown by the increasingly elevated peak viremia with each passage. CONCLUSION: These findings establish that the R5-tropic SHIV-CN97001/Chinese rhesus macaque model should be very useful for the evaluation of HIV-1 subtype C vaccines in China.

Comparing the hippocampal miRNA expression profiles of wild and domesticated Chinese tree shrews (Tupaia belangeri chinensis).

BACKGROUND: The domestication of tree shrews represents an important advance in the development of standardized laboratory animals. Little is known regarding the miRNA changes that accompany the transformation of wild tree shrews into domestic tree shrews. RESULTS: By performing miRNA-seq analysis on wild and domestic tree shrews, we identified 2410 miRNAs and 30 differentially expressed miRNAs in the hippocampus during tree shrew domestication. A KEGG analysis of the differentially expressed genes showed that the differentially expressed miRNAs were associated with ECM-receptor interaction, the phosphatidylinositol signaling system, protein digestion and absorption, inositol phosphate metabolism, lysine degradation, fatty acid degradation and focal adhesion. Most of these pathways could be classified under environmental information processing, organismal systems and metabolism. The miRNAs exclusively expressed in wild and tame tree shrews GO enriched in terms of divergent functions. The miRNA-mRNA networks suggested that novel-m1388-5p and novel-m0746-5p might play regulatory roles in domestication of tree shrews. Real-time RT-PCR analysis was employed to verify the presence of these miRNAs. CONCLUSION: We identified a number of candidate miRNA-regulated domestication genes that may represent targets for selection during the domestication of tree shrews.

First report of Schistosoma sinensium infecting Tupaia belangeri and Tricula sp. LF.

Schistosoma sinensium belongs to the Asian Schistosoma and is transmitted by freshwater snails of the genus Tricula. Rodents are known definitive hosts of S. sinensium. In 2016, suspected schistosome eggs were found in the feces of the northern tree shrew (Tupaia belangeri) in a field in Lufeng County (latitude, 25°04'50″ N; longitude, 102°19'30″ E; altitude 1820 m), Yunnan Province, China. Morphological analysis suggested that the schistosome was S. sinensium. 18S, 12S and CO1 genes sequencing and phylogenetic analysis showed that this species had the highest similarity to and occupied the same evolutionary branch as S. sinensium from Mianzhu, Sichuan, China. Meanwhile, based on 16S and 28S rDNA sequencing and morphological identification, the snail intermediate host was identified as a species of Tricula, and was found in irrigation channels. Phylogeny indicated that Tricula sp. LF was a sister taxon to T. bambooensis, T. ludongbini. The S. sinensium was able to experimentally infect the captive-bred Tupaia belangeri, and Schistosoma eggs were recovered from all Tupaia belangeri exposed. In this study, we report the infection of Tupaia belangeri and Tricula sp. LF with S. sinensium in Lufeng, Yunnan, southwest China. These findings may improve our understanding of the host range, evolution, distribution, and phylogenetic position of S. sinensium.