Factors influencing long-term hepatitis B virus infection of the tree shrew (Tupaia belangeri chinensis) as an in vivo model of chronic hepatitis B / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To determine the methods for establishing an in vivo model of long-term hepatitis B virus (HBV) infection in the Chinese tree shrew (Tupaia belangeri chinensis).</p><p><b>METHODS</b>Seventy-seven neonate (1-3 days old) and 49 young adult (2 weeks to 1 year old) tree shrews were inoculated with different HBV sources (chronic hepatitis B (CHB) human patient serum, single or pooled; HBV-infected tree shrew serum, single only; HBV-infected HepG2.2.15 cells' culture medium supernatant; HBV genome-transfected HepG2.2.15 cells' culture medium supernatant) through various routes of injection (subcutaneous, intraperitoneal, and direct liver via abdominal skin; adults also received intravenous and indirect liver via spleen). Serum and liver biopsies were collected from the animals at various time points post-inoculation for detection of HBV markers by fluorescence quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, time-resolved immunofluorescence, Southern blotting, dot blotting, immunohistochemistry, and microscopy.</p><p><b>RESULTS</b>Among the neonatal group of tree shrews, six (7.8%) were confirmed as HBV-infected for more than 72 (up to 228) weeks after inoculation and another seven (9.1%) were suspected of persistent infections. None of the young adult tree shrews developed persistent infection. Inoculation with single-source serum from either CHB humans or tree shrews were responsible for the most cases of infections, and the subcutaneous injection produced more infections than the other inoculation routes. The most reliable methods of determining HBV infection status were detection of serum HBV immunoreactive markers and intrahepatic HBV DNA.</p><p><b>CONCLUSION</b>In order to establish an in vivo model of CHB in the tree shrew, the animals should be inoculated in the neonatal period using subcutaneous injection.</p>

Proteomic characteristics of the liver and skeletal muscle in the Chinese tree shrew (Tupaia belangeri chinensis)

Valid animal models are useful for studying the pathophysiology of specific disorders, such as neural disease, diabetes and cancer. Previous molecular phylogeny studies indicate that the tree shrew is in the same order as (or a close sister to) primates, and thus may be an ideal model in which to study human disease. In this study, the proteome of liver and muscle tissue in tree the shrew was identified by combining peptide fractionation and LC-MS/MS identification. In total, 2146 proteins were detected, including 1759 proteins in liver samples and 885 proteins in skeletal muscle samples from the tree shrew. Further sub-source analysis revealed that nearly half of the identified proteins (846 proteins and 418 proteins) were derived from human database. In this study, we are the first to describe the characteristics of the proteome from the liver and skeletal muscle of the tree shrew. Phylogenetic tree analysis based on these proteomic data showed that the tree shrew is closer to primates (human) than to glires (the mouse and rat).

Infection of tupaia hepatocytes with hepatitis C virus in vitro / 中华肝脏病杂志

<p><b>OBJECTIVE</b>Tupaia belangeri (tree shrew) has a close phylogenetic relationship with primates and has been shown to be susceptible to a variety of human viruses. This study was conducted to investigate whether or not hepatitis C virus (HCV) could infect primary tupaia hepatocytes (PTHs) in vitro.</p><p><b>METHODS</b>Serum-derived HCV was cultivated with PTHs, and then positive and negative strand HCV RNA in PTHs, as well as the encapsidated HCV RNA in the culture medium were detected to evaluate the infection. Virus from the culture medium of the infected PTHs was passed to naïve PTHs, and the quasispecies of HCV were compared among the inoculum and PTHs after infection and passage.</p><p><b>RESULTS</b>Both positive and negative strand HCV RNA were detected in PTHs after infection. The negative strand RNA was detectable from day 5 to day 10 after infection, while the positive strand RNA was positive up to day 14. HCV RNA, which was RNase resistant, could be detected from the culture medium of the infected PTHs from day 3 to day 14. Production of infectious virons of PTH were demonstrated by passage HCV to naïve PTHs. Compared analysis of HCV quasispecies after infection and passage showed that PTHs were selectively infected with defined HCV quasispecies, and new quasispecies emerged in PTHs after passage.</p><p><b>CONCLUSION</b>The present study strongly indicates that PTHs could be infected by HCV and support HCV replication in vitro. Our results would be helpful for the establishment of a tupaia model of HCV infection.</p>