Pandoravirus

Pandoravirus

Pandoravirus particles under electron microscopy

Pandoravirus is a genus of very large viruses, first discovered in 2013. These viruses are notable for their large size and complex genomes, which are larger than those of some small bacteria. Pandoraviruses are part of the family Pandoraviridae and are known for their unique characteristics that challenge the traditional definitions of viruses.

Discovery

Pandoraviruses were first identified in 2013 by a team of researchers led by Jean-Michel Claverie and Chantal Abergel. The initial discovery was made in water samples collected from a freshwater pond in Chile and a shallow marine sediment off the coast of Australia. The discovery of Pandoravirus was significant because it expanded the known size range of viruses and provided new insights into viral evolution.

Structure

Pandoraviruses are among the largest viruses known, with sizes reaching up to 1 micrometer in length. They have an ovoid shape and are enclosed in a thick protein shell. The large size of Pandoravirus particles allows them to be visible under a light microscope, which is unusual for viruses.

Genome

The genome of Pandoravirus is composed of double-stranded DNA and is remarkably large, containing approximately 2.5 million base pairs. This genome size is larger than that of many bacteria and archaea. The Pandoravirus genome encodes a large number of genes, many of which have no known homologs in other organisms, suggesting a unique evolutionary history.

Replication

Pandoraviruses replicate within the cytoplasm of their host cells. They infect amoebae, such as Acanthamoeba, and utilize the host's cellular machinery to replicate their DNA and produce new viral particles. The replication cycle of Pandoravirus is complex and involves the formation of large viral factories within the host cell.

Evolutionary Significance

The discovery of Pandoravirus has significant implications for our understanding of viral evolution. The large genome and unique gene content of Pandoravirus suggest that it may represent a distinct lineage of viruses that evolved from a common ancestor with cellular life. This challenges the traditional view of viruses as simple entities and suggests that they may have played a more active role in the evolution of life on Earth.

Related pages

• Mimivirus
• Megavirus
• Acanthamoeba
• Viral evolution