Pithovirus

Pithovirus is a genus of giant virus that was first discovered in 2014. It is notable for its large size and complex structure, which challenges traditional definitions of viruses. The only species currently classified under this genus is Pithovirus sibericum.

Discovery

Pithovirus was discovered in a 30,000-year-old permafrost sample from Siberia. The discovery was made by a team of French scientists led by Jean-Michel Claverie and Chantal Abergel. The virus was found to infect amoebas, specifically the species Acanthamoeba castellanii.

Structure

Pithovirus is one of the largest viruses ever discovered, with a length of approximately 1.5 micrometers and a diameter of about 0.5 micrometers. Its size is comparable to that of some small bacteria, such as Mycoplasma. The virus has a unique amphora-shaped structure with a thick protein shell and a dense lipid membrane.

Genome

The genome of Pithovirus is composed of double-stranded DNA and is approximately 600 kilobase pairs in length. Despite its large size, the genome encodes only about 500 proteins, which is fewer than expected for a virus of its size. This suggests that Pithovirus relies heavily on the host cell's machinery for replication.

Replication

Pithovirus replicates within the cytoplasm of its host, Acanthamoeba castellanii. Upon infection, the virus releases its genetic material into the host cell, where it hijacks the host's cellular machinery to produce viral components. These components are then assembled into new viral particles, which are released upon the lysis of the host cell.

Significance

The discovery of Pithovirus has significant implications for our understanding of viral evolution and the potential for ancient viruses to be revived from permafrost. It also raises questions about the diversity of viruses and their role in ecosystems.

Also see

• Giant virus
• Pandoravirus
• Mimivirus
• Acanthamoeba castellanii
• Permafrost

References

• Claverie, J.-M., & Abergel, C. (2014). "The discovery of Pithovirus: A new giant virus from the Siberian permafrost." Proceedings of the National Academy of Sciences.
• Legendre, M., et al. (2014). "Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology." Proceedings of the National Academy of Sciences.