Viruses possess multiple qualities associated with complex lifeforms

Viruses are able to acquire fully functional immune systems, according to a recent study, which adds to the theory that viruses are living creatures.

Scientists previously thought that viruses existed as primitive particles of RNA or DNA and lacked the sophistication of an immune system. The study, published in the journal Nature, is the first to demonstrate that a virus can have an immune system and other qualities often associated with complex lifeforms, Discovery News reports.

Andrew Camilli, the co-author of the study from Tufts University School of Medicine, said that while using a complex immune system does not prove that viruses are living beings, it contributes to the ongoing argument.

"(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," Camilli said, according to Discovery News.

The research team investigated a viral predator of cholera bacteria known as a bacteriophage. The scientists found that the viruses can possess their own immune system and steal an immune system from the bacteria they feed upon.

"The immune system allows the phage to target and destroy specific inhibitory genes of the host cell by literally cutting the target genes into pieces," Kimberley Seed, the lead author of the study, said, according to Discovery News. "(By disarming these genes), the phage essentially disarms the host cell, and can then proceed with the infection and kill the host cell."

Sylvain Moineau, a professor in the department of biochemistry, microbiology and bioinformatics at Université Laval, said that phages are among the most abundant biological entities on the planet, but whether they and other viruses should be considered living organisms remains debatable, Discovery News reports.