Jiejie Dai

Preliminary investigation of viruses to the wild tree shrews(Tupaia belangeri chinese)

Virological testing and monitoring is a fundamental part of quality control of experimental animals. However, there are few papers regarding the spectrum and status of natural infection in wild tree shrews with human and animal pathogenic viruses. Using enzyme-linked immunosorbent adsorption assay (ELISA), we tested sixty wild tree shrews captured from Qinglong, an outskirt region of Kunming, Yunnan Province, China for eleven viruses, including herpes simplex virus, coxsackie virus, influenza virus, HAV, HBV, HCV, HDV, dengue virus, hemorrhagic fever virus and measles virus. Our results showed that, in the serum samples, 22/60 (36.7%) and 1/60 (1.67%) were antibody positive for herpes simplex virus and coxsackie virus, respectively, and 4/60 (6.7%) were antigen positive for rotavirus in the feces. The remaining species of viruses were negative in these tree shrews. Based on these results, we propose that herpes simplex virus, coxsackie virus and cotavirus should be listed as top priority for routine virological monitoring of tree shrews.

[Analysis of the molecular characteristics and cloning of full-length coding sequence of interleukin-2 in tree shrews].

While the tree shrew (Tupaia belangeri chinensis) is an excellent animal model for studying the mechanisms of human diseases, but few studies examine interleukin-2 (IL-2), an important immune factor in disease model evaluation. In this study, a 465 bp of the full-length IL-2 cDNA encoding sequence was cloned from the RNA of tree shrew spleen lymphocytes, which were then cultivated and stimulated with ConA (concanavalin). Clustal W 2.0 was used to compare and analyze the sequence and molecular characteristics, and establish the similarity of the overall structure of IL-2 between tree shrews and other mammals. The homology of the IL-2 nucleotide sequence between tree shrews and humans was 93%, and the amino acid homology was 80%. The phylogenetic tree results, derived through the Neighbour-Joining method using MEGA5.0, indicated a close genetic relationship between tree shrews, Homo sapiens, and Macaca mulatta. The three-dimensional structure analysis showed that the surface charges in most regions of tree shrew IL-2 were similar to between tree shrews and humans; however, the N-glycosylation sites and local structures were different, which may affect antibody binding. These results provide a fundamental basis for the future study of IL-2 monoclonal antibody in tree shrews, thereby improving their utility as a model.

Experimental studies on infant Tupaia belangeri chineses with EV71 infection

Tupaia belangeri are small mammals with a squirrel-like appearance; they were formerly classified under the primates order despite the lack of derived features characteristic of primates. Given that T. belangeri are easy to raise, cheap to maintain, and have a small body size, a high reproductive rate, and close affinity to primates, these animals would be used as an alternative to primates in biomedical research. Three-month old T. belangeri chineses were infected with enterovirus 71 (EV71) via three different routes, namely, oral administration, nasal dripping, and tail intravenous injection, to study the infection in infant T. belangeri and find a feasible scheme to make them an ideal animal model of EV71 in place of primates. Daily activities were regularly observed, body temperatures were measured, and blood tests were conducted. Blood and fecal samples were regularly collected. The infection was examined via the neutralizing antibody test, reverse transcription polymerase chain reaction (RT-PCR), Real-Time PCR, and pathological analysis. The temperature, as well as the white blood cell count and the number of lymphocytes, increased four days after infection. Virus loads were determined in all three groups, and the peak appeared on, before, or after the tenth day, respectively. Thus, oral administration proved to be the best route. The highest serum antibody titer obtained was 1:16. Acute paralysis with urinary retention manifested after about two weeks, and pathological changes were observed in the brain, heart, lung, spleen, kidney, and other tissues. In conclusion, T. belangeri chineses can infected with EV71 via oral administration, nasal dripping, and tail intravenous injection. Therefore, T. belangeri are potential EV71 animal models for further studies on the mechanism of pathogenesis or vaccine evaluation.

Different obesity phenotypes correlated with the PI3K-AKT signaling pathway in tree shrews

Objective To identify the meaningful co-expressed gene network in mRNA extracted from adipose tissue representing different obesity phenotypes in a new tree shrew model. Furthermore, to locate the potential drug target based on analyzing the possible pathways and hub genes responsible for obesity. Methods Ten tree shrews were selected from F1 populations and divided into 3 groups based on their Lee’s index for mRNA sequencing. We identified clusters of highly correlated genes (modules) by weighted gene co-expression network analysis (WGCNA). Results Three modules were strongly correlated with not less than one obesity phenotype (associations ranging from −0.94 to 0.85, P < 0.01). The ribosome, lysosome and ubiquitin-mediated proteolysis pathways were the most enriched pathways of the blue (including 481 genes), brown (389 genes) and turquoise (1781 genes) modules, respectively. The hub genes were determined, including UBA52 in the blue module, AKT1 in the brown module and LRRK2 in the turquoise module. Conclusions We characterized different obesity phenotypes in tree shrews for the first time. The most represented gene AKT1 indicated the vital role of the PI3K-AKT pathway through interactions with downstream pathways and differentially expressed genes (DEGs). The work will help provide new insight into the prevention and treatment strategies of obesity.

Regeneration of islet β-cells in tree shrews and rats

Current understanding of injury and regeneration of islet β‐cells in diabetes is mainly based on rodent studies. The tree shrew is now generally accepted as being among the closest living relatives of primates, and has been widely used in animal experimentation. However, there are few reports on islet cell composition and regeneration of β‐cells in tree shrews.

CircRNAs in the tree shrew (Tupaia belangeri) brain during postnatal development and aging.

Circular RNAs (circRNAs) are a novel type of non-coding RNA expressed across different species and tissues. At present, little is known about the expression and function of circRNAs in the tree shrew brain. In this study, we used RNA-seq to identify 35,007 circRNAs in hippocampus and cerebellum samples from infant (aged 47–52 days), young (aged 15–18 months), and old (aged 78–86 months) tree shrews. We observed no significant changes in the total circRNA expression profiles in different brain regions over time. However, circRNA tended to be downregulated in the cerebellum over time. Real-time RT-PCR analysis verified the presence of circRNAs. KEGG analysis indicated the occurrence of ubiquitin-mediated proteolysis, the MAPK signaling pathway, phosphatidylinositol signaling system, long-term depression, the rap1 signaling pathway, and long-term potentiation in both brain regions. We also observed that 29,087 (83.1%) tree shrew circRNAs shared homology with human circRNAs. The competing endogenous RNA networks suggested novel_circRNA_007362 potential functions as a 24-miRNAs sponge to regulate UBE4B expression. Thus, we obtained comprehensive circRNA expression profiles in the tree shrew brain during postnatal development and aging, which might help to elucidate the functions of circRNAs during brain aging and in age-related diseases.

Characterization of tree shrew (Tupaia belangeri) interleukin-6 and its expression pattern in response to exogenous challenge

Tree shrews, one of the closest relatives of primates, have attracted increasing attention as a model of human diseases, particularly for viral infections. As the first line of defense against microbial pathogens, the innate immune system is crucial in tree shrews. Interleukin-6 (IL-6) is important in the pathophysiology of infection, inflammation and cancer, where it promotes disease development or sustains immune reactions. The present study aimed to obtain further insight into the tree shrew IL-6 (tsIL-6) system, and the function of tsIL-6 in the antiviral and antibacterial response. In the present study, the mRNA and genomic sequence of the tsIL-6 gene were characterized, and the tissue distribution and expression profile of this gene were analyzed in response to lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (poly I:C) treatment. The full-length tsIL-6 mRNA consisted of 1,152 bp with an open reading frame of 627 bp encoding 208 amino acids, a 5′-untranslated region (UTR) of 62 bp, and a 3′-UTR of 436 bp. The genome sequence of the tsIL-6 gene was 5,265 bp in length, comprising of five exons and four introns. The predicted tsIL-6 protein contained a 25-amino-acid-long signal peptide and a conserved IL-6 domain. Phylogenetic analysis based on the coding sequences revealed that tsIL-6 was closely related to IL-6 in humans. Residues crucial for receptor binding were completely conserved in the tree shrew protein. Reverse transcription-polymerase chain reaction analysis revealed that tsIL-6 mRNA was expressed in all examined tissues of healthy tree shrews, with high levels in the muscle and spleen. Following poly I:C challenge, the expression levels of tsIL-6 were upregulated in four tissues associated with immune system, the liver, spleen, kidney and intestine. Taken together, the molecular and bioinformatics analyses based on the IL-6 sequence revealed that the tree shrew has a close phylogenetic association with humans. These results provide insight for future investigations on the structure and function of tsIL-6.