Defensive symbiosis against giant viruses in amoebae

Author(s): Patrick Arthofer, Vincent Delafont, Anouk Willemsen, Florian Panhölzl, Matthias Horn
Abstract: Protists are important regulators of microbial communities and key components in food webs with impact on nutrient cycling and ecosystem functioning. In turn, their activity is shaped by diverse intracellular parasites, including bacterial symbionts and viruses. Yet, bacteria-virus interactions within protists are poorly understood. Here, we studied the role of bacterial symbionts of free-living amoebae in the establishment of infections with nucleocytoplasmic large DNA viruses (Nucleocytoviricota). To investigate these interactions in a system that would also be relevant in nature, we first isolated and characterized a giant virus (Viennavirus, family Marseilleviridae) and a sympatric potential Acanthamoeba host infected with bacterial symbionts. Subsequently, coinfection experiments were carried out, using the fresh environmental isolates as well as additional amoeba laboratory strains. Employing fluorescence in situ hybridization and qPCR, we show that the bacterial symbiont, identified as Parachlamydia acanthamoebae, represses the replication of the sympatric Viennavirus in both recent environmental isolates as well as Acanthamoeba laboratory strains. In the presence of the symbiont, virions are still taken up, but viral factory maturation is inhibited, leading to survival of the amoeba host. The symbiont also suppressed the replication of the more complex Acanthamoeba polyphaga mimivirus and Tupanvirus deep ocean (Mimiviridae). Our work provides an example of an intracellular bacterial symbiont protecting a protist host against virus infections. The impact of virus-symbiont interactions on microbial population dynamics and eventually ecosystem processes requires further attention.
Organisation(s): Department of Microbiology and Ecosystem Science
External organisation(s): Université de Poitiers
Journal: Proceedings of the National Academy of Sciences of the United States of America
Volume: 119
No. of pages: 3
ISSN: 0027-8424
DOI: https://doi.org/10.1073/pnas.2205856119
Publication date: 08-2022
Peer reviewed: Yes
Austrian Fields of Science 2012: 106026 Ecosystem research, 106022 Microbiology
Keywords
ASJC Scopus subject areas: General
Portal url: https://ucrisportal.univie.ac.at/en/publications/defensive-symbiosis-against-giant-viruses-in-amoebae(4e7fb229-bd19-45ee-b6ee-b76fc50012d6).html