Scientists have revived a 30,000 year-old virus from Siberian ice. This virus, named Pithovirus sibericum, even resumed its infectious activity after being thawed out. It is also a very large virus, measuring 1.5 micrometers (that's larger than some bacteria).
http://www.scientificamerican.com/article/giant-virus-resurrected-from-30000-year-old-ice/
