A nonstructural protein encoded by a rice reovirus induces an incomplete autophagy to promote viral spread in insect vectors

PLoS Pathog. 2022 May 9;18(5):e1010506. doi: 10.1371/journal.ppat.1010506. eCollection 2022 May.

Abstract

Viruses can hijack autophagosomes as the nonlytic release vehicles in cultured host cells. However, how autophagosome-mediated viral spread occurs in infected host tissues or organs in vivo remains poorly understood. Here, we report that an important rice reovirus, rice gall dwarf virus (RGDV) hijacks autophagosomes to traverse multiple insect membrane barriers in the midgut and salivary gland of leafhopper vector to enhance viral spread. Such virus-containing double-membraned autophagosomes are prevented from degradation, resulting in increased viral propagation. Mechanistically, viral nonstructural protein Pns11 induces autophagy and embeds itself in the autophagosome membranes. The autophagy-related protein 5 (ATG5)-ATG12 conjugation is essential for initial autophagosome membrane biogenesis. RGDV Pns11 specifically interacts with ATG5, both in vitro and in vivo. Silencing of ATG5 or Pns11 expression suppresses ATG8 lipidation, autophagosome formation, and efficient viral propagation. Thus, Pns11 could directly recruit ATG5-ATG12 conjugation to induce the formation of autophagosomes, facilitating viral spread within the insect bodies. Furthermore, Pns11 potentially blocks autophagosome degradation by directly targeting and mediating the reduced expression of N-glycosylated Lamp1 on lysosomal membranes. Taken together, these results highlight how RGDV remodels autophagosomes to benefit viral propagation in its insect vector.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagosomes / metabolism
  • Autophagy
  • Insect Vectors
  • Insecta / metabolism
  • Orthoreovirus*
  • Oryza* / metabolism
  • Reoviridae* / metabolism
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / metabolism
  • Virus Replication

Substances

  • Viral Nonstructural Proteins

Grants and funding

This project was supported by funds from the National Natural Science Foundation of China to TW under grant number 31920103014 (http://www.nsfc.gov.cn/), the National Natural Science Foundation of China to DJ under grant number 31970160 (http://www.nsfc.gov.cn/), the Natural Science Foundation of Fujian Province to DJ under grant number 2020J06015 (http://xmgl.kjt.fujian.gov.cn/loginSignout.do), the Science, Technology and Innovation Fundation of Fujian Agriculture and Forestry University to TW under grant number CXZX2019004K (https://kyy.fafu.edu.cn/), the Science, Technology and Innovation Fundation of Fujian Agriculture and Forestry University to DJ under grant number CXZX2019021G (https://kyy.fafu.edu.cn/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.