Lymphocystis Disease Virus (Iridoviridae) Enters Flounder (Paralichthys olivaceus) Gill Cells via a Caveolae-Mediated Endocytosis Mechanism Facilitated by Viral Receptors.

Abstract

In previous research, voltage-dependent anion channel protein 2 (VDAC2) and the receptor of activated protein C kinase 1 (RACK1) in flounder (Paralichthys olivaceus) were confirmed as functional receptors for lymphocystis disease virus (LCDV) entry; however, the underlying mechanism of VDAC2- and RACK1-mediated LCDV entry remains unclear. In this study, we elucidated the endocytosis pathway of LCDV entry into flounder gill (FG) cells by treatment with specific inhibitory agents, siRNAs, and co-localization analysis. LCDV entry was significantly inhibited by the disruption of caveolae-mediated endocytosis, dynamin, and microtubules, and the knockdown of caveoline-1 and dynamin expression, but was not inhibited by the disruption of clathrin-mediated endocytosis, micropinocytosis, or low-pH conditions. The disruption of caveolae-mediated and clathrin-mediated endocytosis was verified by the internalization of cholera toxin subunit B (CTB) and transferrin, respectively. Confocal immunofluorescence assay demonstrated that LCDV was co-localized with VDAC2 and RACK1, CTB was co-localized with VDAC2 and RACK1 and partially with LCDV, but transferrin was not co-localized with LCDV, VDAC2, or RACK1, indicating that LCDV utilized the same pathway as CTB, i.e., caveolae-mediated endocytosis. This was different from the pathway of transferrin, which used clathrin-mediated endocytosis. Furthermore, caveolin-1 was co-localized with LCDV, VDAC2, and RACK1, suggesting that caveolin-1 was involved in LCDV entry. These results revealed for the first time that LCDV entered into FG cells via caveolae-mediated endocytosis facilitated by VDAC2 and RACK1 receptors, relying on dynamin and microtubules in a pH-independent manner, which provided new insight into the molecular mechanisms of LCDV entry and potential for the development of antiviral agents, expanding our understanding of iridovirus infection.

• Authors: Xiuzhen Sheng, Ying Zhong, Jing Zeng, Xiaoqian Tang, Jing Xing, Heng Chi, Wenbin Zhan
• Journal: International journal of molecular sciences (Int J Mol Sci) Vol. 21 Issue 13 (Jul 02 2020) ISSN: 1422-0067 [Electronic] Switzerland
• PMID: 32630682 (Publication Type: Journal Article)

Chemical References

• ASC1 protein, S cerevisiae
• Adaptor Proteins, Signal Transducing
• Receptors, Virus
• Saccharomyces cerevisiae Proteins
• Voltage-Dependent Anion Channel 2
• GTP-Binding Proteins

Topics

• Adaptor Proteins, Signal Transducing (metabolism)
• Animals
• Caveolae (metabolism)
• DNA Virus Infections (virology)
• Endocytosis (physiology)
• Fish Diseases (virology)
• Flounder (metabolism, virology)
• GTP-Binding Proteins (metabolism)
• Gills (metabolism, virology)
• Iridoviridae (metabolism, pathogenicity, physiology)
• Receptors, Virus (physiology)
• Saccharomyces cerevisiae Proteins (metabolism)
• Virus Replication (physiology)
• Voltage-Dependent Anion Channel 2 (metabolism)