Observation of virus-like particles in high temperature enrichment cultures from deep-sea hydrothermal vents.

A systematic search was carried out on samples collected in various geographically distant hydrothermal sites located on the East Pacific Rise (EPR 9 degrees N and 13 degrees N) and Mid-Atlantic Ridge (MAR 36 degrees N and 37 degrees N) to investigate the diversity of virus-like particles (VLPs) from deep-sea vents. Eighty-nine positive enrichment cultures were obtained from one hundred and one crude samples at 85 degrees C. VLPs were detected by electron microscopy in fifteen different enrichments. Among the different morphotypes observed, the lemon-shaped type prevailed but rods and novel pleomorphic morphologies were also observed. Several observations strongly suggested that host strains of the novel VLPs belong to the hyperthermophilic euryarchaeal order Thermococcales.