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A NOVEL VIRUS (HaNIV) CAUSES LYSIS OF THE TOXIC BLOOM-FORMING ALGA HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE)
Article first published online: 1 MAY 2002
Journal of Phycology
Volume 37, Issue 2, pages 216–222, April 2001
How to Cite
Lawrence, J. E., Chan, A. M. and Suttle, C. A. (2001), A NOVEL VIRUS (HaNIV) CAUSES LYSIS OF THE TOXIC BLOOM-FORMING ALGA HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE). Journal of Phycology, 37: 216–222. doi: 10.1046/j.1529-8817.2001.037002216.x
- Issue published online: 1 MAY 2002
- Article first published online: 1 MAY 2002
- 1 Received 22 December 1999. Accepted 4 December 2000.
- algal virus;
- Heterosigma akashiwo;
We describe a previously unknown virus that causes lysis of the toxic bloom-forming alga Heterosigma akashiwo (Hada) Hara et Chihara (Raphidophyceae). Heterosigma akashiwo nuclear inclusion virus (HaNIV) does not resemble other algal viruses described to date. HaNIV is small (ca. 30 nm diameter), is assembled in the nucleus, and forms crystalline arrays. We estimate that approximately 105 HaNIV particles are released during lysis of a cell. During a time-course experiment, TEM revealed the first signs of HaNIV infection 24 h after viral addition, and by 74 h 98% of observed cells were visibly infected. The onset of cell lysis, as indicated by a decrease in the relative fluorescence of the cultures, was apparent by 42 h postinfection. The heterochromatin of infected cells is frequently found at the margin of the nucleoplasm, which is consistent with virus-mediated programmed cell death, or apoptosis. HaNIV is clearly different from other described viruses that infect algae, including other viral pathogens of H. akashiwo. These results indicate that viruses other than Phycodnaviridae are pathogens and cause mortality of microalgae in marine systems. It is likely that HaNIV plays an integral role in the population dynamics of H. akashiwo.