Viruses and their role

Source: By Jaspreet Bindra: Mint

Given the panic, death and disruption caused by Covid-19, it may not surprise you that the word “virus" originated in the Sanskrit term vish, or visa, and the Zoroastrian vīša—all meaning poison. Covid-19 is caused by a coronavirus—an ordinary virus which causes the common cold and flu. This particular coronavirus, which hails from Wuhan in China, threatens to become a global pandemic.

But viruses are important to human beings and are, in fact, necessary for the survival of our species. The most numerous biological entity on earth, they are the means of transferring genes between different species, which increases genetic diversity and drives evolution—nearly 10% of the human genome is made of bits of virus DNA. “Viruses are a key part of what make us human," says Prof. Luis P. Villarreal, University of California. They can be considered to be a life form, because they carry genetic material, reproduce, and evolve through natural selection, although they lack a cell structure considered necessary to count as life. Because they possess some but not all such qualities, viruses have been described as “organisms at the edge of life". As nature’s microscopic zombies, viruses straddle the divide between the living and the dead.

Viruses have two other key characteristics: they can only live and propagate by infiltrating a host cell and they jump from species to species. Both these characteristics are what make viruses dangerous.

As we cohabit with machines, viruses have also metaphorically jumped to them, specifically to computers. It was John von Neumann who first described how a computer program could be designed to reproduce itself, and his design for a self-reproducing program is considered to be the world’s first computer virus. Since then, the internet has fuelled multiple “viral epidemics" among computers—Melissa, Iloveyou and Wannacry, among others.

Biological and computer viruses have a lot in common. Both are much simpler than their hosts; a bio virus will have a few thousand genomic base pairs, as compared to three billion of a human cell, and a computer virus may contain as few as six lines of code compared to the tens of millions of lines of codes of an operating system. Both are nothing without their host. They need a host to survive and replicate by sending copies of themselves through coughs and sneezes, or emails and messages, as the case might be. Both kill by decreasing host performance. Both conceal themselves inside their hosts, making detection very difficult from white blood cells or from basic virus detection programs.

Despite the recent bad name they have gotten, viruses can be incredibly useful for us humans. Bacteriophage—a kind of virus—actively kills harmful bacteria, especially in the mucus membranes in our noses and our guts. Biologists have engineered viruses to form vaccines against Hepatitis B, and are trying to get viruses to engineer cells that may provide cures for diseases such as emphysema and cystic fibrosis. Even CRISPR/Cas9, a technology that can be used to edit genes and could thus change the world, owes some of its origin to bacteriophage viruses.

In an innovative use of viruses, Dr Angela Belcher of the Massachusetts Institute of Technology used them to assemble a lithium-ion battery’s positive and negative electrodes, creating the world’s first “living battery". They boost battery performance and do not have the toxic residue that regular Li-ion battery electrodes have. When she first submitted this idea as a post-doctoral grant proposal, the reviewer declared it “insane".

Now, however, she has crafted viruses that work with 150 different materials for batteries, and demonstrated how this technique can be used to biologically manufacture solar cells. “The benefit of using viruses is that they already exist in this ‘nano’ form, so they are essentially a natural template or scaffold for the synthesis of battery materials," says Konstantinos Gerasopoulos of Johns Hopkins Applied Physics Laboratory. Belcher’s genetically-engineered viruses cannot differentiate between an anode and a cathode, but they don’t need to. Their DNA is only programmed to do a simple task, but when millions of viruses perform the same task together, they produce a usable material.

Belcher, in fact, dreams of zipping around in a “virus-powered car". When that inevitably happens, perhaps we will have a reverse kind of machine zoonosis, where viruses jump from a car to its driver, another point in favour of driverless cars, perhaps?