A T4 bacteriophage injecting DNA into a cell. Providing an effective mechanism for delivering human genetic therapy is one of the ways these stigmatised parasites are proving their true value to humanity. Credit: Wikimedia
As far as words with negative connotations go, it’s hard to top ‘virus’. AIDS, bird flu, Dengue fever, Ebola – and that’s just in the first few letters of the alphabet. And when Agent Smith tells Morpheus in The Matrix that he considers the human race a virus, it’s widely understood that he’s not paying a compliment.
But for a rising number of scientists, viruses aren’t sinister at all. Instead, they are at the forefront of the latest advances in genetic technology, bringing hope to those with previously incurable diseases.
Hitchhikers, hijackers & hosts
Martha Chase and Alfred Hershey used viruses to help establish that DNA, rather than protein, forms the basis of heredity. Cheap, quick to produce, and easy to modify, a core group of viruses has filled out the toolboxes of many a biologist ever since.
Their ability to entwine themselves with the host’s genome has made viruses the darlings of the field of gene therapy. The once outlandish scenario of going into a person’s cells and correcting genetic ‘typos’ is now an earnest aim of researchers, who hope intentional viral infections will one day help sufferers of diseases such as Parkinson’s and Severe Combined Immunodeficiency (SCID), also known as ‘bubble boy syndrome’, a mutation in the genome that prevents the body’s immune system from functioning.
Researchers plan to ‘hijack the hijackers’ – swapping the virus’ harmful genes for a corrected version of the patient’s defective genes and using the virus’ unique abilities to insert the gene into patient’s genome. In reality, the procedure is fraught with difficulties, not least getting the right amount of gene in the right location without side effects.
Pavel Osten from Northwestern University in Chicago, Illinois, recently co-authored a paper on the use of viruses as DNA delivery systems, or vectors. “In my view, it is most likely that this work [gene therapy] will become a mainstream treatment of some of the devastating brain disorders for which there is currently no treatment,” he wrote.
But how would you feel about being injected with a virus to cure a disease? According to Osten, the risks are low and decreasing. “The viral vectors … are in most cases stripped down to the most basic elements that are required for gene delivery, and thus in no possible way pose any risk with respect to the original disease.”
Viruses don’t attack only animal cells, however. The vast majority of viruses actually target bacteria, including the bacteria that infect humans; they are called bacteriophages, or phages for short (from the Greek phagein, to consume). “For years researchers have been looking at using this targeted bacterial killing as an alternative to antibiotics,” says Jason Clark from Moredun Research Institute in Scotland. While this might seem a bit like inviting in the barbarians, it’s also sound science; in August of last year, the U.S. Food and Drug Administration (FDA) approved a bacteriophage food spray designed to reduce the amount of illness-causing bacteria on ready-to-eat meals.
It’s a virus’ world
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Hey, agent Smith professes his theory that human beings are a disease to MORPHEUS, not Neo.
Dear Hamish,
That is a fascinating article on viruses. Thanks very much for it.
I have one picky little comment. In paragraph 5 you say viruses suicide. Suicide is a noun not a verb, and you should have said commits suicide, self destructs, or just dies. I taught English for years and this is one of my peeves.
Early on Sunday mornings, if I’m awake, I listen to ABC’s Innovations. It is a fascinating program and I wish it was broadcast later in the day. Have you ever listened to CBC’s Quirks and Quarks? Another great science program.
Best wishes to all you Aussies,
Ken Bryden
West Vancouver BC
Both corrected – thanks for pointing it out.
Bests
Wilson da Silva
Editor-in-Chief
Nice article but I have one query.
You said that it is assumed that the total number of viruses exceeds every living cell by a factor of ten. But a virus needs a host cell to exist so this would mean that on average every living cell in the world is host to 10 viruses.
Obviously not every cell in the world can be infected to this extent so my question is what is the average number of viruses in a living cell that has been affected? Or else, what is the number of viruses in the cell before it causes the cell to ‘explode’?
Not all viruses need a host cell to exist, and many can exist in the environment for long periods of time.
It may be one of your peeves, but it is technically grammatically correct.
from the Merriam-Webster Dictionary…
suicide (verb)
Definition of SUICIDE
intransitive verb
: to commit suicide
transitive verb
: to put (oneself) to death
Hello Sir,
Awesome article. I find it fascinating. The thing that has my brain in a spin though is that I favor Creation and Science together and I’d like to pick your brain regardless of your personal bias.
If Evolution did take place, as Science suggests, then what are your theories/hypothesis on why viruses have not evolved into larger organisms? Would they not have evolved around the same time? Theoretically, why aren’t we all dead or at least all infected with some kind of harmless virus?
My understanding is that viruses evolve very rapidly comparatively. My “understanding” could be the fault. It just seems to me that viruses would have already won the “Evolution race” as it were.
(Sorry. I’m asking out of genuine interest in your opinion and not trying to spark a religious debate. lol My brain instinctively asks “Why? Why? Why?” like a kid that just learned what why means.)
we do all have harmless viruses. one example is cold sores, or herpes. and yes viruses do evolve quickly. And this is ot my personal bias this is true (and maybe my personal bias)
Weird, I think. Kinda bad article. No offense, but…just telling what I say. Let’s just put it like this… just get straight to the point in your writing. I’ve seen far better articles.
There are viruses that live in the host without causing symptoms, or even in a symbiotic relationship, as part of the host’s natural life. A certain virus is necessary for the reproduction of some wasp (and it became a permanent part of it’s host’s genome!), and some other virus is 100% necessary for the reproduction of sheep (go on google for more info.) Besides, one cell can contain many viruses before it busts open and also, one cell can host many different kinds of viruses. I can’t see a problem with that factor of 10 even without thinking about viruses outside of a host cell.
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