This Article Full Text Full Text (PDF) Other Versions of this Article: AEM.00509-08v1 74/13/4022    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Shirai, Y. Articles by Nagasaki, K. PubMed PubMed Citation Articles by Shirai, Y. Articles by Nagasaki, K. Agricola Articles by Shirai, Y. Articles by Nagasaki, K.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, July 2008, p. 4022-4027, Vol. 74, No. 13
0099-2240/08/$08.00+0     doi:10.1128/AEM.00509-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Isolation and Characterization of a Single-Stranded RNA Virus Infecting the Marine Planktonic Diatom Chaetoceros tenuissimus Meunier

Yoko Shirai,¹ Yuji Tomaru,^1* Yoshitake Takao,^1, Hidekazu Suzuki,² Tamotsu Nagumo,³ and Keizo Nagasaki¹

National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima 739-0452, Japan,¹ Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan,² Department of Biology, Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-9159, Japan³

Received 2 March 2008/ Accepted 23 April 2008

Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a single-stranded RNA (ssRNA) virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and 1 x 10⁴ infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this virus is its exceptionally high yields of 10¹⁰ infectious units ml^–1; this is much higher than those of any other algal viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting virus, Rhizosolenia setigera RNA virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this virus, these data strongly suggest the existence of a diatom-infecting ssRNA virus group in natural waters.

Published ahead of print on 9 May 2008.

Present address: Department of Marine Bioscience, Fukui Prefectural University, 1-1 Gakuen-cho, Obama, Fukui 917-0003, Japan.