Love thy virus

Bacteria are getting more and more resistant to antibiotics like penicillin. A way around this might be to use viruses to attack bacteria.
26 August 2014

Interview with 

Heather Hendrickson, Massey University


Pseudomonas bacteria


Antibiotics were first discovered in the 1920s.  They've since save millions of lives, but within just a few years of them being introduced, resistant bacteria were already cropping up.  Now, we're at a stage where there are some infections afflicting humans here on Earth that we just can't treat.  But Heather Hendrickson who's lecturer in molecular biosciences at Massey University is exploring how we might be able to go back and use an older technology to solve this more modern day problem.

Heather -  The older idea that you're talking about in fact is, instead of thinking about using chemicals that bacteria and other microorganisms have been using against one another, let's just try using something like a microorganism.  And so, the idea here is that there are bacterial viruses.  So, viruses that exclusively infect bacteria and that if we can find targeted groups of bacteriophages which is the name for these viruses that only infect bacteria, then maybe we could come up with cocktails of bacteriophages that would be effective treatments.  We could actually take them as a therapeutic agent instead of taking something like an antibiotic.

Chris -   It's ironic to think that bacteria can catch a cold than humans.

Simon -   Yeah.

Heather -   It's much worse than a cold.

Chris -   So, what happens to it?

Heather -   Yeah, so what happens with a bacteriophage infecting a bacterial cell is that in fact, the bacteriophage will adhere to the bacterial cell and then many of them actually have this like, injector core tail.  So they're basically like - bacteriophages are just protein capsules and they have a little tail and they have like a little spider-like end often.  They kind of attach onto the cell and inject this core down into these cells and it just flood the cell with their copy of their DNA.  Usually, this is only like 50 genes, so pretty small.  But that 50 genes or so that's injected in allows the bacteriophage to take over the machinery of the bacterial cell, build hundreds, often, copies of itself and then ultimately, it explodes the bacterial cell, releasing hundreds of copies of itself.  So, it's a lot worse than a cold.

Simon -   Wow!  So, the tail, this injection thing is like the phages going in there and taking over the photocopier in the office, getting all the printer and just print all this weird stuff.

Heather -   Really very similar.  That's a great analogy, yeah.

Chris -   Photocopying your bottom.

Heather -   How did I not think of that before?

Chris -   Nice to hear about Radio New Zealand National office party.  So, when they do this, they get into the cell, they make hundreds of copies of the bacteriophage, burst the bacterial cell, and what those new copies, would then go off and track down and kill more of the same bacteria.

Heather -   Right and I think that one thing to remember is that they don't actually - this is a real problem actually with online videos of these things.  They often look like they're kind of swimming.  They're out seeking for their next lunch or their next parasitism candidate.  But actually, they're completely inert.  So, they're just these protein shells with a little bit of DNA inside and there's like very lethal-looking tail, little spidery bit.  But they are completely inert.  They don't have any ability to generate ATP.  They don't have any energy source or anything.  So, they just kind of bump into the next cell.  It's really about the particular molecular identity of the bacterial cell and the bacteriophage that allows them to be specific.  Actually, it's that specificity that's one of the things that make them really interesting in terms of therapeutic agents in the future.

Chris -   You mean as in, that they can only get into bacterial cells.

Heather -   Well, only bacterial cells and all of the bacteriophage that we've ever found have very specific bacterial targets.  And so, if I find a bacteriophage that's really good at infecting some kind of pseudomonas, it's not very likely that that's going to be able to infect some kind of mycobacterium or some kind of E. coli.  The reason that that's really cool, especially when we compare it to this antibiotics.  And the things that we're going through in terms of antibiotics is that antibiotics are often very like broad spectrum which means that you dump antibiotics into your system, you've got lots of really good for you kinds of bacteria in your system, and that antibiotic almost goes off like a small nuclear bomb, right?  And so, it just kills tons of these bacteria, tons of bacteria that are really good for you.  The thing about a bacteriophage is because it's so targeted, if you can figure out what's making you ill and you can take a cocktail of these bacteriophages that are making you ill, then they'll only kill the bacteria that are making you ill.  And that's really powerful actually, compared to what we've been dealing with.

Simon -   So, why haven't we got them today?  What's going on?

Heather -   What's that?  What had happened?

Simon -   Why haven't we got them in action today?  What's stopping you?

Heather -   So actually, I should say that there was a time in Russia and in Russian Georgia where phage therapy was the 'done' thing.  And so, phage therapy has been used for human therapeutics in the past, but it's not currently approved right now.  And so, one of the things that I'm doing at Massey University is, I have a class of undergraduates and we're trying to find new bacteriophages.

Chris -   And you're using them as victims.

Heather -   I'm using them as scientists.

Chris -   Just checking.

Heather -   I have a group of undergraduates and they go out and they bring us soil samples and then they take the soil samples and they search for bacteriophages.  So far, we've found about a half-dozen bacteriophages.  We've sequenced 3 and what the students are able to do is find their very own bacteriophage, completely unique, it's never been seen before.  They're able to name them and then we sequenced the genome of each of these bacteriophages.  And so, the students actually get the opportunity to look at the DNA of a completely novel organism and using the kinds of bioinformatic tools that we have access to today.  Figure out where the genes are and what the genes are in this completely new entity.  The undergraduates in my class are going to be publishing a paper with me on this.

Chris -   Will they be potentially therapeutic, any of these?  Will they attack human infecting bacteria or are they just infecting soil bacteria?

Heather -   So, it's all about the target organism that you use and we happen to be using a pseudomonad.  So, this is a safe pseudomonas.

Chris -   It's another kind of bacteria, isn't it - pseudomonas?

Heather -   Yes.  So this is a pseudomonas that's like really beneficial to plants, but it's very closely related to Pseudomonas originosa which is the really problematic agent in cystic fibrosis.  It's also very closely related to Pseudomonas Syringae actinidiae which is the kiwifruit pathogen.  And so, we're hoping that in the future, we can find bacteriophages that you would be able to - for example, if you had a big load of pollen that was headed on into the kiwifruit industry here in New Zealand.  you could spread these bacteriophages onto...

Chris -   Because you import pollen to fertilise crops, don't you?

Heather -   Yeah.  It's a really important part of the way the kiwifruit industry works here because of the male female bias in the orchards for example.

Chris -   So of course, if you brought in pollen that was contaminated with a pathogen, obviously, New Zealand may have very good buyer security at the airport but if you've got some microscopic freeloader in your pollen then you could infect your crops here and this would be devastating.  But you're saying, you could have a bacteriophage, a virus that would attack any bacteria that are in the pollen and wipe them out.

Heather -   And it would be very specific.  The other nice thing about bacteriophage is if you have those kinds of entities then they of course degrade.  They're made out of protein in DNA and they're delicious to lots of organisms.  So you sprayed them on the pollen.  They infect anything that's there and then they're basically going to be recycled.


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