Study on Susceptibility and Infection Characteristics of Dengue Virus in Cells Sourced from Different Tissues of Tree Shrews

Objective To investigate the susceptibility and infection characteristics of dengue virus (DENV) in cells derived from diverse tissues of tree shrews and to provide a basis for expanding the repertoire of DENV-permissive cell models in this species.MethodsDENV was inoculated at a multiplicity of infection (MOI) of 0.02 into tree shrew skin fibroblasts (TSFs), primary tree shrew renal epithelial cells (pTRECs), tree shrew aortic endothelial cells (TAECs), tree shrew aortic smooth muscle cells (TASMCs), tree shrew hepatocytes (THs), tree shrew corneal stromal cells (TCSCs), tree shrew brain microvascular endothelial cells (TBMECs), and tree shrew retinal microvascular endothelial cells (TRMECs). C6/36, Vero, A549, and BHK-21 cells (commonly used for DENV propagation) were used as positive controls. Over 6 days post-infection, cellular cytopathic effects were monitored at 12-hour intervals using an inverted microscope, viral RNA loads in cell lysates were quantified by real-time fluorescent quantitative PCR to generate proliferation curves, and viral titers were determined by plaque assay. Results Seven types of tree shrew cells, except TRMECs, were susceptible to DENV. Prolonged infection induced pronounced cytopathic effects, including cell rounding, detachment, necrosis, and lysis, across all susceptible cells. The viral RNA loads detected in lysates of pTRECs, TBMECs, TASMCs, TAECs and THs, approached those of positive controls (≥4×10⁷ copies/μL). Infectious progeny viruses were produced by these five cell types, with three (TAECs, 3.13×105 PFU/mL; THs, 2.03×105 PFU/mL; pTRECs, 1.58×105 PFU/mL) exhibiting titers comparable to C6/36 (3.85×10⁵ PFU/mL) and earlier viral harvests.ConclusionDENV exhibits broad susceptibility to tree shrew cells of multiple tissue origins, with proliferation rates surpassing those of conventional cell lines sourced from other species. TAECs, THs, and pTRECs are particularly suitable for large-scale DENV proliferation, suggesting their potential involvement in in vivo infection.