"Virus factories" and more are found in an amoeba within contact lens fluid.

In July of last year, researchers in France described a rather disturbing example of what could happen if you're not careful about cleaning your contact lenses. A 17-year-old patient had been wearing monthly lenses well past their expiration date, and rinsing them with a cleaning solution she'd diluted with tap water. The end result was an eye infection. Luckily, a bit of care managed to clear it up.

In the meantime, the people who treated her dumped some of the solution out of her contact lens case and started trying to culture any parasites that would grow out of it. In the end, they got an entire ecosystem—all contained inside a single strain of amoeba. Among the parasites-within-parasites were a giant virus, a virus that targets that virus, and a mobile piece of DNA that can end up inserting into either of them.

When they first grew the amoeba from the contact lens cleaning solution, they found it contained two species of bacteria living inside it. But they also found a giant virus, which they called Lentille virus. These viruses have been known for a while, and they tend to affect amoebas, so this wasn't a huge surprise.

More recently, however, researchers discovered these viruses can get viruses. Or, more precisely, virophages. Upon infecting an amoeba, the giant virus builds what's become called a "virus factory" within the cell, where its genetic material is copied and new viruses are built from parts encoded by its genes. The virophages can spread from amoeba to amoeba, but once they enter the cell, they head straight for the virus factory, where they get replicated.

When the scientists sequenced the genome of the Lentille virus, it had a few surprises for them. To begin with, it contained a new virophage of its own, which they called Sputnik 2. An infected amoeba would release virophage particles, suggesting that the virus could move between these organisms on its own. But the authors also found a copy of the virus inserted into the giant Lentille virus genome. And, if an amoeba were infected with one of these giant viruses, it would also start producing the virophage.

In other words, the virophage has two ways of spreading. Like any other virophage, it can spread from amoeba to amoeba, and will find a home in any that also contain a Lentille virus. But once it finds one, it inserts itself into its giant viral genome, ensuring that any future amoeba it infects gets a copy of the virophage, too. Although it has a preference to jump into the giant virus genome, it can hop elsewhere. That could potentially cause mutations and speed up the evolution of its host.

But that wasn't the only parasite the authors found in Lentille virus. A shorter sequence, one containing six genes, was also associated with the viral genome. As with the virophage, this sequence was found as both a free-standing piece of DNA and inserted into the genome of the Lentille virus. But there was a rather significant difference: none of the genes it carried encoded the sorts of proteins that are used to package a virus. Instead, it had several features normally found in transposons, mobile genetic elements that hop around the genomes of organisms ranging from bacteria to mammals.

As if there weren't enough names to deal with, the authors deemed this DNA element a "transpoviron," for a transposon that targets a virus. They showed that, shortly after an infection with a Lentille virus, its resident transpoviron would be copied out of its host genome, form into circle, and start making copies of itself. These copies were then available to insert into genomes of any other viruses that were around—there's even some evidence that a copy inserted into Sputnik 2 in the past.

By looking at the sequences of some other giant viruses, they also concluded that Lentille virus isn't alone in carrying these molecular parasites.

The authors conclude by painting a picture of the giant viruses as supporting an entire DNA-based ecosystem of mobile genetic elements, which spread to other amoebas (and other viruses) by a variety of means. Given that we've found so much so shortly after starting to look, the authors suggest that we've likely only scratched the surface of its diversity.

Promoted Comments

A lot of questions here are explained in the first link in the article Below are a few questions from the above comments with quotes from the case (which is really worth a read btw, even if you don't understand all the jargon)...

Q:

dechicago wrote:

Ok...but other than not diluting with water and not using lenses past their expiration date, is there anything contact lens wearers should know or do?

A:"...Patients should be informed of the risk for keratitis caused by water-borne, amebal-resistant pathogens. They should also be educated to avoid contact with tap water when manipulating contact lenses, to dry hands after washing them with water and soap, or to use antiseptics containing >70% alcohol for hand disinfection before contact lens manipulation."

The most important question for me...where the heck where the amoeba come from? Shouldn't tap water be clear of things like this? I've heard amoeba's can be potentially dangerous, especially if you're bathing and it gets into your ears or whatnot.

A:"Acanthamoeba spp. are ubiquitous in tap water (2,5), including that used by contact lens wearers to wash hands before manipulating the lens (8). Tap water hosts many organisms, including bacteria (2,5); large DNA viruses (9); and the recently described Sputnik virophage, a virus that infects ameba-resistant large DNA viruses (10)."

Note: I added the fluoroquinolone link to the 2nd quote in case anyone is interested in what exactly it is

92 Reader Comments

Her first mistake was diluting it with tap water. Contact solution is meant to be sterile for a reason. Diluting it with tap water just introduces a whole load of bacteria. You try looking at it under a microscope? It will certainly change the way you see it.

In the article it says they used the solution that was diluted with tap water. So is it really fair to apply this to all contact solution like the title implies?

wearing monthly lenses well past their expiration date, and rinsing them with a cleaning solution she'd diluted with tap water. The end result was an eye infection.

*sigh*

/me facepalm

I think it implies she's a moron.

Quote:

In other words, the virophage has two ways of spreading. Like any other virophage, it can spread from amoeba to amoeba, and will find a home in any that also contain a Lentille virus. But once it finds one, it inserts itself into its giant viral genome, ensuring that any future amoeba it infects gets a copy of the virophage, too.

Woah... cool. I have no idea if this is truly rare or if it's merely uncommon...?

Am I the only one who thinks this is an amazing find none the less? Granted I'm only in my second semester of medical science I still see huge potential for genetic engineering or possible even new treatments for virus infection. Think about HIV. We really can't target the virus with our own immune system. What if some virophage adds some key "markers" to the HIV genome so it does become targetable by our own immune cells?

Am I the only one that stopped reading after the first paragraph realizing it was pointless link bait?

-kpluck

Even though it was link bait, i generally liked the content which I'm guessing most people did.

To be honest, when we worked on the title, we didn't see this possible interpretation. People are really quick to assume malice when, in this case, i simply knew all the background already and interpreted this potential title through that (if you'll pardon the pun) lens.

Clearly, people had a different interpretation than i did, and it was causing confusion, so we've tried to clarify it.

Am I the only one that stopped reading after the first paragraph realizing it was pointless link bait?

-kpluck

Even though it was link bait, i generally liked the content which I'm guessing most people did.

To be honest, when we worked on the title, we didn't see this possible interpretation. People are really quick to assume malice when, in this case, i simply knew all the background already and interpreted this potential title through that (if you'll pardon the pun) lens.

Clearly, people had a different interpretation than i did, and it was causing confusion, so we've tried to clarify it.

Oh, I don't know if it was malice. All in good fun... at your expense of course! But, that's a sacrifice I'm willing to make.

Okay, so I certainly don't dilute my solution with tap water, and I dump the solution and change it daily, but I do wear my lenses way beyond a month, usually until they start bugging me, tear, etc. I know I should change this habit, but what is it that makes it more likely to have a problem after a month's usage, if it's being sanitized daily? Does this mean the solution actually leaves some stuff behind every day, and after a month's time it just can't get clean enough anymore?

Okay, so I certainly don't dilute my solution with tap water, and I dump the solution and change it daily, but I do wear my lenses way beyond a month, usually until they start bugging me, tear, etc. I know I should change this habit, but what is it that makes it more likely to have a problem after a month's usage, if it's being sanitized daily? Does this mean the solution actually leaves some stuff behind every day, and after a month's time it just can't get clean enough anymore?

Also, how did they clear up the infection? You never said.

They probably cleared the infection with antibiotics. Eye infections are relatively simple to treat assuming the infection isn't left untreated causing complications.

Title is still kind of crappy because in a certain interpretation it still implies used contact solution. Which could be implied as any solution that isn't just freshly opened contains viruses.

On the other side of the spectrum this really is a story that can be filed under duh. Anyone could tell you that diluting sterile contact solution with non sterile tap water would cause problems.

Having a title like "Tap water diluted solution is a viral oasis" would make people question the reasoning of even reporting it.

Well, take that a little further and use a title like "Tap water diluted solution becomes a Russian-doll viral oasis". I would have enjoyed the article just the same as I'm no bio expert and find that little ecosystem quite fascinating. Thanks for another interesting article, John,

I have Keratoconus so I have to wear hard contacts. I don't even want to know what kind of crap are on those things though I'm quite diligent in cleaning them (nightly and I replace the solution whenever I put them back in). I rarely put them on anymore since they really bother my eyes if I wear them for more than a 4 hours. Si as you can imagine I'm nearly blind as bat, at this moment face is about 10 inches away from the screen I'm typing this on.

Anyway, this article scared the crap out of me for those rare occasions when I want to wear my contacts.

Okay, so I certainly don't dilute my solution with tap water, and I dump the solution and change it daily, but I do wear my lenses way beyond a month, usually until they start bugging me, tear, etc. I know I should change this habit, but what is it that makes it more likely to have a problem after a month's usage, if it's being sanitized daily? Does this mean the solution actually leaves some stuff behind every day, and after a month's time it just can't get clean enough anymore?

Also, how did they clear up the infection? You never said.

They probably cleared the infection with antibiotics. Eye infections are relatively simple to treat assuming the infection isn't left untreated causing complications.

Eye infections get treated with steroids in most cases. Very few antibiotics that work well for eyes. Eye infections are never trivial - your eyes are the front end of your spinal column and infections that get into that region can plaque you for life.

Cleaning of lenses only removes a percentage of the proteins and dust. Yes, it does build up over time and can scratch the lens of your eye. .

Okay, so I certainly don't dilute my solution with tap water, and I dump the solution and change it daily, but I do wear my lenses way beyond a month, usually until they start bugging me, tear, etc. I know I should change this habit, but what is it that makes it more likely to have a problem after a month's usage, if it's being sanitized daily? Does this mean the solution actually leaves some stuff behind every day, and after a month's time it just can't get clean enough anymore?

Also, how did they clear up the infection? You never said.

They probably cleared the infection with antibiotics. Eye infections are relatively simple to treat assuming the infection isn't left untreated causing complications.

Eye infections get treated with steroids in most cases. Very few antibiotics that work well for eyes. Eye infections are never trivial - your eyes are the front end of your spinal column and infections that get into that region can plaque you for life.

Cleaning of lenses only removes a percentage of the proteins and dust. Yes, it does build up over time and can scratch the lens of your eye. .

If the reason you wear 1-day disposables is fear of amoebas with giant viruses in them, with other viruses in those, with mobile DNA in those, then i would say you're probably being over specific with your fears.

The most important question for me...where the heck where the amoeba come from? Shouldn't tap water be clear of things like this? I've heard amoeba's can be potentially dangerous, especially if you're bathing and it gets into your ears or whatnot.