Ad Infinitum

Fact: Viruses can get viruses.

We are just cells, and parasites that we call viruses (or phage) that kill those cells in order to replicate. In exactly the same way, bacteria have viruses too – those care called bacteriophage. When it starts to get spinny is when you realise that viruses themselves have viruses – the tiny virophage.

These meta-viruses were discovered infecting the largest known virus – the mamavirus family (as far as viruses go, mamaviruses are really really big – larger even than the world’s smallest bacterium). These virophages hijack the mamavirus to produce copies of itself, and the mamavirus even gets ‘sick’ as the virophage steals valuable nutrients and energy. The host virus dies 70% of the time after it gets infected. That’s the same mortality rate as Ebola.

For those confused by the title, it’s taken from a poem by Jonathan Swift (1733):

So, naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite ’em,
And so proceed ad infinitum.

It means ‘to infinity’. How right he was.

‘Another one of Mr Shaunak’s Little Bites of Science’
Image under Creative Commons license, taken by NIH NIAID from


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