Inés: If you're not a biologist you might associate microbes with "bad germs" that make
you ill, but today I'm joined by my friend Suzie Ford.
Suzie: Hi! Inés: Who's an expert in microbial interactions
and we are going to give you a very different perspective on microbes.
[INTRO by Caro Waro & Cristina de Manuel]
Inés: You’ve probably heard of the term ‘good’ bacteria from probiotic yogurt
adverts, but what does that even mean? Suzie: Well, along with other microorganisms,
like fungi and viruses, there are thousands of species of bacteria that live on and in
your body that perform diverse functions. In your intestine, for example, there are
bacteria that digest nutrients in your diet and develop your immune system. But they don’t
just do that. Research over the last few decades has found more and more cases of microbes
that actually protect their hosts from pathogens and parasites, effectively fighting our battles
for us! Inés: As a result of these findings, scientists
are beginning to look at how we can use these microbes to control infectious diseases in
humans, animals and plants, including crops. And this is a pretty big deal.
Suzie: So how do they work? Well, most protective microbes in nature have been found to protect
host organisms by a diversity of mechanisms. Some microbes defend us directly, by feeding
on the pathogen, or producing toxic compounds that kill or make the pathogen grow slower.
Other microbes may simply compete for the same food as the pathogen, and if they’re
better at it, they will starve the pathogen to death. In some cases, these microbes can
also trigger the host’s immune system against the pathogen, or increase the host’s fitness
by other means, for example by preventing the pathogen from damaging tissues, or by
helping to repair them more quickly. Inés: This is great, and hopefully you might
be wondering, what’s in it for the microbes? How do they evolve to be helpful to their
hosts in the first place? Well, there are two main ways we think microbes can evolve
to be protective. The first is simply that they end up protecting the host as a by-product
of say, competing with a pathogen to live in the host or even by eating the pathogen
itself. The other way is where the microbe is directly selected to be protective. This
usually occurs when the microbe depends on the host being healthy to ensure their own
survival. This can be the case when the microbes are transmitted from parents to offspring,
such that their fitness depends on the host successfully reproducing. Some hosts also
select for protective microbes by punishing those that don’t cooperate.
Suzie: Yep! And one really cool example of these protective microbes is a bacterium called
Wolbachia. Basically it’s the wonder-woman of bacteria. Wolbachia live inside the cells
of insects and are found in over half of all insect species. What’s really cool about
this bacterium though is that it has been found to protect insects from infection. Now
I know you’re thinking: why the hell would we care about protecting insects from disease?
But what scientists have found is that actually by infecting mosquitoes with Wolbachia, when
normally they don’t carry Wolbachia, they can protect them against diseases like dengue
fever, malaria, yellow fever, west nile virus, chikungunya and more recently, even zika virus.
And these diseases infect us. So that’s a lot of people that can be protected.
Inés: Another thing that makes Wolbachia a really promising strategy is how it can
be introduced into a population. It’s all great having a bacterium that prevents the
transmission of mosquito-borne disease, but how do you get it into all of the mosquitoes
in the first place? Inés: Wolbachia affects how insects are able
to reproduce in a way that makes them spread very quickly without much additional help.
One of the most common ways is through what is known as cytoplasmic incompatibility. Essentially,
what this means is that if a female has Wolbachia, her eggs will always hatch and will always
contain Wolbachia, whereas if a female without Wolbachia mates with a male with Wolbachia,
her eggs won’t hatch at all. This means that over time, there will be more individuals
with Wolbachia in each generation. Suzie: So, as a result of this, Wolbachia
is strategically excellent, it is efficient, self-sustaining, and really cost-effective.
Not only this, but the strategy is environmentally friendly. So far release trials have been
carried out with really promising results, spreading Wolbachia into mosquito populations
responsible for transmitting dengue fever. With this we will soon be able to tell how
effective it could really be. Inés: And *this* is precisely what Suzie
is going to be researching in her new postdoc in Australia, so Wolbachia (we'll back-ya!)
every step of the way! ;) ;)
Suzie: [Laughter] Naff! Inés: Bo-doom-tss!
Inés: Anyway, we hoped you enjoyed this, thank you so much Suzie for being in this
episode with me today and for sharing your future research with us, and stay tuned because
we're also going to be making a video about some recent current research that Suzie's been
working on (the video) - and as always, thank you so much for watching us, and *we* will
see you in the next one! Suzie: Bye!
[Translated into {Language} by {Your Name}]