Most viruses are miniscule, The influenza virus measures about 100 nanometers across, and has just 13 genes.In the past decade larger viruses have been found. French researchers recently discovered a giant virus which has a volume larger than the flu virus by a thousand-fold, and contains 2,556 genes. Interestingly the genes found only match 6% of the known genes on earth.
Viruses were discovered on tobacco plants in the 1800s by scientists. Infected leaves were mashed up with water and passed through a filter. The resultant clear liquid had the ability to infect other tobacco plants. Martinus Beijerinck a Dutch botanists called it a "contagious living fluid." The advent of powerful new microscopes in the 1930s allowed viruses to become observable. It was found that viruses hijacked other cells to reproduce.
In 2003 French scientists discovered the first giant virus, which they originally thought was a bacterium. It contained 979 genes, and was found living inside amoebae that dwelled in a water cooling tower. They named the viruses pandoraviruses. Once it was found scientists began to search for other giant viruses.
In 2009 Didier Raoult and a team of researchers discovered Marseillevirus in an amoeba. The virus is 250 nanometers in diameter and has a chimeric genome with DNA & RNA present consisting of 368,000 base pairs.
In 2011, Dr. Claverie and a team of researchers found megaviruses with 1,120 genes in the ocean near Chile. Digging further down into the sediment they discovered pandoraviruses with over double the amount of genes present in megaviruses. Claverie speculates the viruses evolved from microbes the branched off from other life forms several billion years ago.
Amoeba are eukaryotic cells that live in water & damp soils. Some amoebae are parasitic organisms. Amobea are capable of digesting a...