Viral DNA Accumulation Regulates Replication Efficiency of Chlorovirus OSy-NE5 in Two Closely Related Chlorella variabilis Strains

Ahmed Esmael; Irina V Agarkova; David D Dunigan; You Zhou; James L Van Etten

doi:10.3390/v15061341

Viral DNA Accumulation Regulates Replication Efficiency of Chlorovirus OSy-NE5 in Two Closely Related Chlorella variabilis Strains

Viruses. 2023 Jun 9;15(6):1341. doi: 10.3390/v15061341.

Authors

Ahmed Esmael^{1

2}, Irina V Agarkova^{1

3}, David D Dunigan^{1

3}, You Zhou⁴, James L Van Etten^{1

3}

Affiliations

¹ Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA.
² Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt.
³ Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA.
⁴ Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.

Abstract

Many chloroviruses replicate in Chlorella variabilis algal strains that are ex-endosymbionts isolated from the protozoan Paramecium bursaria, including the NC64A and Syngen 2-3 strains. We noticed that indigenous water samples produced a higher number of plaque-forming viruses on C. variabilis Syngen 2-3 lawns than on C. variabilis NC64A lawns. These observed differences led to the discovery of viruses that replicate exclusively in Syngen 2-3 cells, named Only Syngen (OSy) viruses. Here, we demonstrate that OSy viruses initiate infection in the restricted host NC64A by synthesizing some early virus gene products and that approximately 20% of the cells produce a small number of empty virus capsids. However, the infected cells did not produce infectious viruses because the cells were unable to replicate the viral genome. This is interesting because all previous attempts to isolate host cells resistant to chlorovirus infection were due to changes in the host receptor for the virus.

Keywords: Chlorella variabilis; DNA accumulation; OSy-NE5; algal viruses; chloroviruses; intracellular resistance; restriction.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Chlorella*
DNA, Viral / genetics
Paramecium*
Phycodnaviridae* / genetics
Viral Proteins / genetics

Substances

DNA, Viral
Viral Proteins

Grants and funding

Funding for this study was partially provided by the NSF-EPSCoR under grant 1736030 (JVE and DDD), the University of Nebraska—Lincoln Agricultural Research Division and the Office of Research and Economic Development (DDD), the University of Nebraska Foundation Algal Virus Research Funds (JVE), and Egyptian Ministry of Higher Education and Scientific Research (AE).