Virus that infects larger virii

A tinsy little virus called "Sputnik" with only 21 genes preys on larger, more developed viruses, infecting them and hijacking their resources to reproduce and spread:

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.

The team suggests that Sputnik is a 'virophage', much like the bacteriophage viruses that infect and sicken bacteria. "It infects this factory like a phage infects a bacterium," Koonin says. "It's doing what every parasite can – exploiting its host for its own replication."

'Virophage' suggests viruses are alive

(via /.)