1. Academic Validation
  2. White Spot Syndrome Virus Benefits from Endosomal Trafficking, Substantially Facilitated by a Valosin-Containing Protein, To Escape Autophagic Elimination and Propagate in the Crustacean Cherax quadricarinatus

White Spot Syndrome Virus Benefits from Endosomal Trafficking, Substantially Facilitated by a Valosin-Containing Protein, To Escape Autophagic Elimination and Propagate in the Crustacean Cherax quadricarinatus

  • J Virol. 2020 Nov 23;94(24):e01570-20. doi: 10.1128/JVI.01570-20.
Chuang Meng 1 Ling-Ke Liu 1 Dong-Li Li 1 Rui-Lin Gao 1 Wei-Wei Fan 1 Ke-Jian Wang 1 Han-Ching Wang 2 Hai-Peng Liu 3 4
Affiliations

Affiliations

  • 1 State Key Laboratory of Marine Environmental Science, State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China.
  • 2 Department of Biotechnology and Bioindustry Sciences, College of Biosciences and Biotechnology, National Cheng Kung University, Tainan, Taiwan.
  • 3 State Key Laboratory of Marine Environmental Science, State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China haipengliu@xmu.edu.cn.
  • 4 Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
Abstract

As the most severely lethal viral pathogen for crustaceans in both brackish water and freshwater, white spot syndrome virus (WSSV) has a mechanism of Infection that remains largely unknown, which profoundly limits the control of WSSV disease. By using a hematopoietic tissue (Hpt) stem Cell Culture from the red claw crayfish Cherax quadricarinatus suitable for WSSV propagation in vitro, the intracellular trafficking of live WSSV, in which the acidic-pH-dependent endosomal environment was a prerequisite for WSSV fusion, was determined for the first time via live-cell imaging. When the acidic pH within the endosome was alkalized by chemicals, the intracellular WSSV virions were detained in dysfunctional endosomes, resulting in appreciable blocking of the viral Infection. Furthermore, disrupted valosin-containing protein (C. quadricarinatus VCP [CqVCP]) activity resulted in considerable aggregation of endocytic WSSV virions in the disordered endosomes, which subsequently recruited autophagosomes, likely by binding to CqGABARAP via CqVCP, to eliminate the aggregated virions within the dysfunctional endosomes. Importantly, both autophagic sorting and the degradation of intracellular WSSV virions were clearly enhanced in Hpt cells with increased autophagic activity, demonstrating that Autophagy played a defensive role against WSSV Infection. Intriguingly, most of the endocytic WSSV virions were directed to the endosomal delivery system facilitated by CqVCP activity so that they avoided Autophagy degradation and successfully delivered the viral genome into Hpt cell nuclei, which was followed by the propagation of progeny virions. These findings will benefit anti-WSSV target design against the most severe viral disease currently affecting farmed crustaceans.IMPORTANCE White spot disease is currently the most devastating viral disease in farmed crustaceans, such as shrimp and crayfish, and has resulted in a severe ecological problem for both brackish water and freshwater aquaculture areas worldwide. Efficient Antiviral control of WSSV disease is still lacking due to our limited knowledge of its pathogenesis. Importantly, research on the WSSV Infection mechanism is also quite meaningful for the elucidation of viral pathogenesis and virus-host coevolution, as WSSV is one of the largest animal viruses, in terms of genome size, that infects only crustaceans. Here, we found that most of the endocytic WSSV virions were directed to the endosomal delivery system, strongly facilitated by CqVCP, so that they avoided autophagic degradation and successfully delivered the viral genome into the Hpt cell nucleus for propagation. Our data point to a virus-sorting model that might also explain the escape of other enveloped DNA viruses.

Keywords

antiviral immunity; autophagy; endosomal trafficking; valosin-containing protein; white spot syndrome virus.

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