  The first giant virus was identified in 2003 from a biofilm of an industrial
water-cooling tower in England. Later, numerous new giant viruses were found in
oceans and freshwater habitats, some of them having even 2,500 genes. We have
demonstrated their very likely presence in four soil samples taken from the
Kutch Desert (Gujarat, India). Here we describe a bioinformatics work-flow,
called the "Giant Virus Finder" that is capable to discover the very likely
presence of the genomes of giant viruses in metagenomic shotgun-sequenced
datasets. The new tool is applied to numerous hot and cold desert soil samples
as well as some tundra- and forest soils. We show that most of these samples
contain giant viruses, and especially many were found in the Antarctic dry
valleys. The results imply that giant viruses could be frequent not only in
aqueous habitats, but in a wide spectrum of soils on our planet.
