Viruses pass major test to enter ranks of living
Baku, March 1 (AZERTAC). Viruses can acquire fully functional immune systems, according to new research that bolsters the controversial theory that viruses are living creatures.
Until now, scientists thought that viruses existed only as primitive particles of DNA or RNA, and therefore lacked the sophistication of an immune system.
The study, published in the journal Nature, is the first to show that a virus can indeed possess an immune system, not to mention other qualities commonly associated with complex life forms.
The belief that viruses are living creatures “stems from the fact that viruses have their own complex genome, they replicate to make more of themselves, and they are evolving,” co-author Andrew Camilli of the Tufts University School of Medicine told Discovery News.
The use of a complex immune system “doesn’t prove” that viruses are living beings, “but it does add to the argument,” he said.
Living organisms are typically defined as being capable of vital functions, such as the ability to grow and adapt to the environment over successive generations. Viruses are now on the fence between being considered a biological entity and an actual living creature.
Camilli and his colleagues focused their investigation on a viral predator of cholera bacteria. This type of virus is known as a bacteriophage (“phage” for short).
Lead author Kimberley Seed, a postdoctoral fellow in Camilli’s lab, was analyzing DNA sequences of phages taken from stool samples of Bangladesh cholera patients. She was surprised to find genes for a functional immune system previously only found in some types of bacteria.
To verify the discovery, she and her colleagues used phages both with and without the immune system to infect a new strain of cholera bacteria. Only the virus harboring the immune system readily killed the cholera bacteria.
Not only can some viruses have an immune system; some also can steal them from bacteria.
The scientists found that viruses can capture immunity genes from bacteria during a phase when “the viral genome is being replicated into dozens of copies within the infected host cell,” Camilli explained. The virus therefore steals an immune system from the bacteria. This benefits the phage virus.
The researchers hope that this activity could battle “superbugs,” which are bacteria with a resistance to most are all current antibiotics.
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