Cold-Active Viruses

Virus-like particles (VLP) are abundant in the aquatic biosphere, typically ranging between 10⁵ and 10⁸ ml⁻¹, including in the cold environments of the deep sea, polar oceans, sea ice and high-latitude lakes. In these places, viruses play important ecological roles, e.g., equaling or surpassing grazers as agents of bacterial mortality in some Arctic waters (Steward et al. 1996; Wells and Deming 2006a). Systematic investigations of viral ecology in snow, permafrost or glaciers are only beginning, but viruses are present, preserved or even active there (e.g., Castello et al. 1999; Säwström et al. 2007b). Yet, despite the prevalence on Earth of environments ≤4°C and the high abundance of viruses in them, little is known about corresponding viral characteristics or ecology. Instead, viral studies have largely been restricted to higher temperatures convenient for experimenters but of little ecological or evolutionary relevance to many viruses.