Hijacking of an autophagy-like process is critical for the life cycle of a DNA virus infecting oceanic algal blooms

Daniella Schatz, Adva Shemi, Shilo Rosenwasser, Helena Sabanay, Sharon G. Wolf, Shifra Ben-Dor, Assaf Vardi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

Summary: Marine photosynthetic microorganisms are the basis of marine food webs and are responsible for nearly 50% of the global primary production. Emiliania huxleyi forms massive oceanic blooms that are routinely terminated by large double-stranded DNA coccolithoviruses. The cellular mechanisms that govern the replication cycle of these giant viruses are largely unknown. We used diverse techniques, including fluorescence microscopy, transmission electron microscopy, cryoelectron tomography, immunolabeling and biochemical methodologies to investigate the role of autophagy in host-virus interactions. Hallmarks of autophagy are induced during the lytic phase of E. huxleyi viral infection, concomitant with up-regulation of autophagy-related genes (ATG genes). Pretreatment of the infected cells with an autophagy inhibitor causes a major reduction in the production of extracellular viral particles, without reducing viral DNA replication within the cell. The host-encoded Atg8 protein was detected within purified virions, demonstrating the pivotal role of the autophagy-like process in viral assembly and egress. We show that autophagy, which is classically considered as a defense mechanism, is essential for viral propagation and for facilitating a high burst size. This cellular mechanism may have a major impact on the fate of the viral-infected blooms, and therefore on the cycling of nutrients within the marine ecosystem.

Original languageAmerican English
Pages (from-to)854-863
Number of pages10
JournalNew Phytologist
Volume204
Issue number4
DOIs
StatePublished - 1 Dec 2014
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2014 New Phytologist Trust.

Keywords

  • Algal blooms
  • Atg8
  • Autophagy
  • Coccolithophores
  • Emiliani huxleyi
  • Emiliania huxleyi virus
  • Nucleocytoplasmic large DNA virus

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