Virophage

Virophage is a type of virus that infects other viruses. The term "virophage" was first coined in 2008 when the Sputnik virophage was discovered. Virophages are unique in that they require the co-infection of a host cell with a larger virus to replicate.

Discovery

The first virophage, the Sputnik virophage, was discovered in 2008 in a water cooling tower in Paris, France. The discovery was made by a team of scientists led by Didier Raoult. The Sputnik virophage was found to infect the mamavirus, a type of giant virus.

Characteristics

Virophages are small, with a diameter of about 50 nanometers. They have a circular double-stranded DNA genome. The genome of a virophage is much smaller than that of the viruses they infect. For example, the Sputnik virophage has a genome of only 18,343 base pairs, while the mamavirus has a genome of over 1.2 million base pairs.

Virophages replicate by hijacking the replication machinery of larger viruses. When a host cell is co-infected with a virophage and a larger virus, the virophage uses the larger virus's replication machinery to replicate its own genome. This can inhibit the replication of the larger virus, leading to fewer virus particles being produced.

Examples

In addition to the Sputnik virophage, several other virophages have been discovered. These include the Mavirus, which infects the Cafeteria roenbergensis virus, and the Organic Lake virophage, which infects the Phycodnaviridae.

Impact on Host Cells

The impact of virophages on their host cells is not fully understood. However, it is believed that they may play a role in controlling the populations of larger viruses. By inhibiting the replication of larger viruses, virophages may help to prevent the destruction of host cells.

See Also

• Virus
• Giant virus
• Sputnik virophage
• Mavirus
• Organic Lake virophage