Soft-shelled turtle iridovirus enters cells via cholesterol-dependent, clathrin-mediated endocytosis as well as macropinocytosis
- 210 Downloads
Ranaviruses are nucleoplasmic large DNA viruses that can cause major economic losses in the aquaculture industry and pose a severe threat to global ecological diversity. The available literature demonstrates that classifiable members of the genus Ranavirus enter cells via multiple and complicated routes. Here, we demonstrated the underlying cellular entry mechanism of soft-shelled turtle iridovirus (STIV) using green fluorescence tagged recombinant virus. Treatment with chlorpromazine, sucrose, ethyl-isopropyl amiloride, chloroquine or bafilomycin A1 all significantly decreased STIV infection, suggesting that STIV uses clathrin-mediated endocytosis and macropinocytosis to enter cells via a pH-dependent pathway. Depletion of cellular cholesterol with methyl-β-cyclodextrin significantly inhibited STIV entry, but neither filipin III nor nystatin did, suggesting that STIV entry was cholesterol dependent but caveola independent. Treatment with dynasore, genistein, ML-7 or cytochalasin D all significantly inhibited STIV infection, indicating that Rac GTPase and myosin II activity were required for the macropinocytosis-like pathway as well as actin polymerization. Our findings suggest that the molecular events involved in STIV entry are not identical to those of other ranavirus isolates. Our results also extend our understanding of the molecular mechanism of iridovirus entry and pathogenesis.
We thank Jianlin Zhang for his help with flow cytometry analysis.
This work was supported by grants from the National Natural Science Foundation of China (31172445), National Key R&D Program of China” (2017YFC1404504), and the Knowledge Innovation Program of the Chinese Academy of Sciences (SQ201014).
Compliance with ethical standards
Conflict of interest
All the authors have no conflict of interest to declare.
This article does not contain any studies with human participants or animals performed by any of the authors.
- 13.Guo CJ, Liu D, Wu YY, Yang XB, Yang LS, Mi S, Huang YX, Luo YW, Jia KT, Liu ZY, Chen WJ, Weng SP, Yu XQ, He JG (2011) Entry of tiger frog virus (an Iridovirus) into HepG2 cells via a pH-dependent, atypical, caveola-mediated endocytosis pathway. J Virol 85:6416–6426CrossRefPubMedPubMedCentralGoogle Scholar
- 17.Wang S, Huang X, Huang Y, Hao X, Xu H, Cai M, Wang H, Qin Q (2014) A novel marine DNA virus (Singapore grouper iridovirus, SGIV) entry into host cells occurs via clathrin-mediated endocytosis and macropinocytosis in a pH-dependent manner. J Virol 88:13047–13063CrossRefPubMedPubMedCentralGoogle Scholar
- 19.Zhu YQ, Wang XL (2016) Genetic diversity of ranaviruses in amphibians in China: 10 new isolates and their implications. Pak J. Zool 48:107–114Google Scholar
- 23.Huang YH, Huang XH, Liu H, Gong J, Ouyang ZL, Cui HC, Cao JH, Zhao Y, Wang X, Jiang YL, Qin QW (2009) Complete sequence determination of a novel reptile iridovirus isolated from soft-shelled turtle and evolutionary analysis of Iridoviridae. BMC Genomics 10:224CrossRefPubMedPubMedCentralGoogle Scholar
- 35.Raghu H, Sharma-Walia N, Veettil MV, Sadagopan S, Chandran B (2009) Kaposi’s sarcoma-associated herpesvirus utilizes an actin polymerization-dependent macropinocytic pathway to enter human dermal microvascular endothelial and human umbilical vein endothelial cells. J Virol 83:4895–4911CrossRefPubMedPubMedCentralGoogle Scholar
- 39.Haspot F, Lavault A, Sinzger C, Laib Sampaio K, Stierhof YD, Pilet P, Bressolette-Bodin C, Halary F (2012) Human cytomegalovirus entry into dendritic cells occurs via a macropinocytosis-like pathway in a pH-independent and cholesterol-dependent manner. PLoS One 7:e34795CrossRefPubMedPubMedCentralGoogle Scholar