Sanada Takahiro, Tsukiyama-Kohara Kyoko, Kohara Michinori
Viral Infection Control Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
Transboundary Animal Diseases Center, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.
Infect Genet Evol. 2025 Aug;132:105778. doi: 10.1016/j.meegid.2025.105778. Epub 2025 Jun 2.
The northern tree shrew (Tupaia belangeri) is recognized as a valuable animal model for studying hepatitis B and C viruses (HCV). However, natural infections of tree shrews remain to be fully characterized. In this study, we identified tree shrew hepaciviruses 1 and 2 and tree shrew pegivirus in liver samples and determined their complete genome sequences. The sequences of these viruses encoded a single large polyprotein, similar to other Flaviviridae viruses. In the 5' untranslated region, tree shrew hepaciviruses possesses miR-122 binding sites, which is involved in liver tropism of HCV, whereas tree shrew pegivirus did not. Genetic analysis revealed 58 % amino acid homology between the polyproteins of tree shrew hepaciviruses 1 and 2. Tree shrew hepacivirsues were genetically close to the rodent hepacivirus (Hepacivirus P) detected in long-tailed ground squirrels, and tree shrew pegivirus was close to Pegivirus scotophili detected in bats. Analysis of viral infections revealed that, among the 37 tree shrews tested, 26 were positive for tree shrew hepacivirus 1, of which 15 were also positive for tree shrew hepacivirus 2. Only one tree shrew was positive for the pegivirus. These data indicate that the tree shrews used as experimental animals were infected with various viruses and that viral genomic characterizations are essential for classifying viral species and understanding viral characteristics and evolution. Furthermore, this study will be useful for screening viral infections to establish the tree shrew as a more stable experimental animal.
北树鼩（Tupaia belangeri）被认为是研究乙型和丙型肝炎病毒（HCV）的一种有价值的动物模型。然而，树鼩的自然感染情况仍有待全面描述。在本研究中，我们在肝脏样本中鉴定出了树鼩肝炎病毒1型和2型以及树鼩pegivirus，并确定了它们的完整基因组序列。这些病毒的序列编码一种单一的大的多聚蛋白，与其他黄病毒科病毒相似。在5'非翻译区，树鼩肝炎病毒拥有miR-122结合位点，这与HCV的肝脏嗜性有关，而树鼩pegivirus则没有。遗传分析显示，树鼩肝炎病毒1型和2型的多聚蛋白之间有58%的氨基酸同源性。树鼩肝炎病毒在基因上与在长尾地松鼠中检测到的啮齿动物肝炎病毒（Hepacivirus P）接近，而树鼩pegivirus与在蝙蝠中检测到的嗜暗pegivirus接近。病毒感染分析显示，在测试的37只树鼩中，26只树鼩肝炎病毒1型呈阳性，其中15只树鼩肝炎病毒2型也呈阳性。只有一只树鼩的pegivirus呈阳性。这些数据表明，用作实验动物的树鼩感染了多种病毒，并且病毒基因组特征对于病毒种类的分类以及理解病毒特征和进化至关重要。此外，本研究将有助于筛选病毒感染，从而将树鼩确立为一种更稳定的实验动物。
