The question whether biological viruses are forms of life has been debated, since they lack the respiratory and metabolic process of other accepted life forms. Naturally, different scientists have different reasons for opinions either way.

So how does the new virus-infecting-virus work?

With just 21 genes, Sputnik is tiny compared with its mama — but insidious. When the giant mamavirus infects an amoeba, it uses its large array of genes to build a ‘viral factory’, a hub where new viral particles are made. Sputnik infects this viral factory and seems to hijack its machinery in order to replicate. The team found that cells co-infected with Sputnik produce fewer and often deformed mamavirus particles, making the virus less infective. This suggests that Sputnik is effectively a viral parasite that sickens its host — seemingly the first such example.

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“It was the cause of great excitement in virology,” says Eugene Koonin at the National Center for Biotechnology Information in Bethesda, Maryland. “It crossed the imaginary boundary between viruses and cellular organisms.”

Science fiction, fantasy and the popular imagination have been fueled in recent decades by the concept of the cyborg, that fusion of machine and creature — but under the scientists’ new definition, even your laptop might be evidence of life…provided it’s infected by a computer virus.