1. Some parasitic wasps lay eggs in caterpillars, where they mature into adult wasps. The wasp eggs contain a virus, encoded in the wasp genome, which prevents the caterpillar from rejecting the eggs.
2. There are a million virus particles per milliliter of seawater – for a global total of 1030 virions! Lined up end to end, they would stretch 200 million light years into space.
3. The genetic information of viruses can be DNA or RNA; single or double stranded; one molecule or in pieces.
4. The name virus was coined from the Latin word meaning slimy liquid or poison.
5. Walter Reed discovered the first human virus, yellow fever virus, in 1901.
6. Viruses are not alive – they are inanimate complex organic matter. They lack any form of energy, carbon metabolism, and cannot replicate or evolve. Viruses are reproduced and evolve only within cells.
7. Over 1016 human immunodeficiency virus genomes are produced daily on the entire planet. As a consequence, thousands of viral mutants arise by chance every day that are resistant to every combination of antiviral compounds in use or in development.
8. The first human influenza virus was isolated in 1933. In 2005, the 1918 pandemic influenza virus strain was constructed from nucleic acid sequence obtained from victims of the disease.
9. The biggest known viruses are mimiviruses, which are 400 nanometers (0.0004 millimeters) in diameter. The viral genome is 1,200,000 nucleotides in length and codes for over 900 proteins.
10. The smallest known viruses are circoviruses, which are 20 nanometers (0.00002 millimeters) in diameter. The viral genome is 1,700 nucleotides in length and codes for two proteins.
Bonus fact: The HIV-1 genome, which is about 10,000 nucleotides long, can exist as 106020 different sequences. To put this number in perspective, there are 1011 stars in the Milky Way galaxy and 1080 protons in the universe.