The biggest virus, based on capsid diameter, is Mamavirus, with a capsid diameter of 500 nanometers, as noted in the provided references. While some viruses might have larger genome sizes, the capsid diameter is a key measure of overall virus size.
Giant Viruses and Their Size
Giant viruses, like those listed below, are known for being unusually large compared to other viruses. These viruses are large enough to be seen using a light microscope. Below is a comparison of some of the biggest known giant viruses, showing their genome length and capsid diameter:
| Giant virus name | Genome Length | Capsid diameter (nm) |
|---|---|---|
| Megavirus chilensis | 1,259,197 | 440 |
| Mamavirus | 1,191,693 | 500 |
| Mimivirus | 1,181,549 | 500 |
| M4 (Mimivirus variant) | 981,813 | 390 |
Key Points about Giant Viruses
- Size matters: These viruses are significantly larger than most other viruses, blurring the lines between viruses and bacteria.
- Complex Genomes: Giant viruses typically have very large genomes, encoding for a wide range of proteins.
- Light Microscope Visibility: Their size allows them to be viewed under a regular light microscope, whereas most viruses require an electron microscope.
While Megavirus chilensis has the largest genome, Mamavirus and Mimivirus have a bigger capsid, meaning they take up more space physically. Therefore, when asking about the "biggest virus", it typically refers to the capsid diameter, in which case Mamavirus takes the title.
