Isolation and Characterization of a Single-Stranded DNA Virus Infecting Chaetoceros lorenzianus Grunow

Abstract

Diatoms are one of the most significant primary producers in the ocean, and the importance of viruses as a potential source of mortality for diatoms has recently been recognized. Thus far, eight different diatom viruses infecting the genera Rhizosolenia and Chaetoceros have been isolated and characterized to different extents. We report the isolation of a novel diatom virus (ClorDNAV), which causes the lysis of the bloomforming species Chaetoceros lorenzianus, and show its physiological, morphological, and genomic characteristics. The free virion was estimated to be ϳ34 nm in diameter. The arrangement of virus particles appearing in cross-section was basically a random aggregation in the nucleus. Occasionally, distinctive formations such as a ring-like array composed of 9 or 10 spherical virions or a centipede-like array composed of rod-shaped particles were also observed. The latent period and the burst size were estimated to be <48 h and 2.

First evidence for the existence of pennate diatom viruses

“…Previously reported centric diatom ssRNA and ssDNA viruses accumulate in their host cytoplasm and nucleus, respectively (Tomaru et al, 2009;Tomaru et al, 2011b), which agrees to the present observations. On the basis of the above results, we concluded that the particles in the host cells and in the lysates were viruses.…”

Isolation and characterization of a single-stranded DNA virus infecting the marine planktonic diatom Chaetoceros sp. (strain TG07-C28)

“…The major protein bands of these three viruses are located between 22 and 46 kDa (Nagasaki et al 2005, Tomaru et al 2011b). Furthermore, ClorDNAV infecting Chaetoceros lorenzianus Grunow contains just a single major polypeptide of 225 kDa (Tomaru et al 2011c), which differed to that of the virus isolated in the present study.…”

“…3C). Both the virion assemblage site and particle diameter were similar to that of ssDNA diatom viruses, CtenDNAV (Tomaru et al 2011b) and ClorDNAV (Tomaru et al 2011c). Since (i) the algicidal pathogen was transferable to a fresh algal culture, (ii) VLPs were observed in the lysed culture, and (iii) VLPs were not found in healthy cultures, we concluded that the 32-34 nm particles observed within the infected cells and in the algal lysates comprised a highly plausible virus that is pathogenic to Chaetoceros sp.…”

“…strain TG07-C28. To date, four different ssDNA viruses that infect Chaetoceros species have been reported; specifically, CsalDNAV, CdebDNAV, CtenDNAV, and ClorDNAV (Nagasaki et al 2005, Tomaru et al 2011b, Tomaru et al 2011c. The virus identified in this study is the fifth case of an ssDNA virus infecting the genus Chaetoceros.…”

Morphological characters of Chaetoceros lorenzianus (Bacillariophyceae) isolated from North Arabian Sea after Tasman Spirit oil spill

“…This species was studied by a number of scientists (Cupp 1943, Subrahmanyan 1946, Hendey 1964, Moazzam 1973, Hasle & Syvertsen 1997, Shevchenko et al 2006, Sunesen et al 2008, Tabassum & Saifullah 2010. Moreover the lysis of this species by a single stranded DNA virus has also been investigated (Tomaru et al 2011). The occurrence of Chaetoceros lorenzianus has been discussed from various parts of the world ocean (Cupp 1943, Sunesen et al 2008, Shevchenko et al 2006, Wood 1963, Subrahmanyan 1946, Rajasekar et al 2010, Hendey 1964 It is known from North Arabian Sea bordering Pakistan (Moazzam 1973, Saifullah & Chaghtai 2005, Tabassum & Saifullah 2010.…”