Natures wonders: Cell conducts anti-viral warfare (Introduction)

by David Turell , Wednesday, October 26, 2016, 23:44 (2948 days ago) @ David Turell

A single celled animal self-sacrifices itself and releases viral making protein to kill attacking virus:

https://www.newscientist.com/article/2110407-kamikaze-cells-wage-biowarfare-and-fight-v...

"The single-celled predator, Cafeteria roenbergensis, is common in coastal waters around the world, where it snacks on bacteria... But Cafeteria has a deadly enemy of its own, the giant CroV virus.

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"...giant viruses, discovered only in 2003, are more like living cells than normal viruses. They have the machinery to make proteins, which means they are vulnerable to viral attack themselves. For example, maviruses infect CroVs, forcing them to make more maviruses instead of CroVs, as Matthias Fischer, now at the Max Planck Institute in Germany, discovered in 2011.

"That, of course, is good news for Cafeteria, because mavirus halts the spread of CroV.

"And Cafeteria has evolved to exploit the concept that the enemy of my enemy is my friend. Rather than waiting for maviruses to arrive by chance when CroVs attack, it actually carries the genes that code for mavirus inside its own genome.

"These genes are usually dormant, but they get turned on when Cafeteria is invaded by CroV. “It acts as an inducible antiviral defence system,” write Fischer and his colleague Thomas Hackl in a new preprint paper.

"The infected Cafeteria cell still dies – but when it breaks apart it releases maviruses rather than CroVs, preventing the spread of the infection. This, then, is altruistic behaviour, which turns out to be surprisingly common among microbes. For instance, some bacteria kill themselves as soon as they are infected by viruses to prevent the infection spreading.

"Other microbes form spore-bearing structures, with the cells making the stalk sacrificing themselves to give the spore-forming cells at the top a chance of surviving.

"Cafeteria may not be the only animal to use living bioweapons to defend itself. A wide range of animals, from sea anemones to crocodiles, harbour genetic elements called Maverick transposons that closely resemble the mavirus genes. It’s possible that some of these organisms can also unleash viruses that attack giant viruses.

"It is common for viral genes to end up inside the genomes of animals. In fact, our genomes are littered with the mutant remains of viruses and genetic parasites.

"Many viruses deliberately insert their genes into the genomes of the animals they attack, so they can lie dormant and emerge when conditions are favourable. In response, most animals have evolved ways of shutting down genes that code for viruses.

"It is, however, extremely unusual for an animal to deliberately trigger virus production, as Cafeteria does – but then mavirus is unusual, too, because it targets another virus rather than Cafeteria itself.

Comment: Another 'how did it develop' problem. Does the Cafeteria do this to protect others of its type? Or is it simply a byproduct of getting killed. And if that is true how did it develop and get passed on to subsequent generations. Death doesn't pass on bacterial inheritance, only cell splitting to daughter cells does that. God did it?