00.00 (Loud
audio mosquito buzzing)
Swarming
mosquitoes
Mosquito
biting
Mosquitoes
in cage
Door
of insectary opened revealing researchers at microscopes
Guide Voice: Today in the west, the buzzing of
a mosquito is an irritation, harbinger of a painful
itch, but for the 40% of the world’s population living
in areas with malaria it can be a death knell.
Malaria infection spread by the mosquito causes more than three
million acute illnesses and at least a million deaths every year,
particularly among children under five. Malaria is a growing
threat, and with climate change could even endanger previously safe
areas around the globe.
Researchers at the Institute for Science and Technology in
Medicine at Keele University, in the West Midlands, are studying
Malaria by focusing their efforts on trying to break the
transmission cycle through which malaria is passed on, by studying
the complex relationship between the parasite and the mosquito
itself.
00.52 SOT: Paul Eggleston, Professor of Molecular
Entomology, School of Life Sciences, Keele University -
“Despite all of our best efforts, malaria is still a huge
and growing problem. It’s been estimated that malaria kills a
child in sub-Saharan Africa about once every 30 seconds. We have
growing problems with insecticide resistance – we now have
mosquitoes which are resistant to every class of insecticidal
compound that we can throw at them, the parasites themselves are
becoming resistant to all of the drugs we can use to try and tackle
the disease. So we’re starting to think about this complex
set of interactions that take placed between the mosquito and the
parasite and whether there are ways within that set of interactions
that we can tackle the transmission cycle itself.”
01.28 Seq
Mosquitoes in cages
Lined
up
Guide Voice: In the past the commonly held
belief was that the mosquito’s role was that of a
“flying syringe” merely carrying the parasite, but
research has shown that both the mosquito and the parasite affect
each other in complex ways, and this might present opportunities to
break the transmission cycle of the disease at what is already a
vulnerable point:
01.46 SOT: Hilary Hurd, Professor of Parasitology,
School of Life Sciences, Keele University - “I
think one of the surprising things is that it takes so long for the
malaria parasite to develop in the mosquito. It takes around 15
days and the mosquito in the wild often only lives that long. So
it’s very much a tight rope that the parasite’s
walking, it must keep it’s mosquito alive long enough for it
to survive to transmit it once it’s infective back into the
next person. So that time period is the key aspect of the life
cycle.”
02.11 Insectary
Mosquito
Cages
Hands
into cages to feed
Mosquitoes
fed
Guide Voice: One discovery of particular
interest is that many of the parasites contained in the blood cells
a mosquito absorbs during a blood meal, are killed off within the
mosquito’s gut within the first twenty – four
hours.
At Keele they think that one method by which this is done is a
means known as "programmed cell death", so they are
investigating how this is triggered, and whether that action could
be enhanced.
Another area of weakness they have discovered in this complex
parasitic relationship, is that the infected female mosquito
produces fewer eggs.
The likelihood is that this is a resource management strategy,
keeping more resources so the mosquito lives longer allowing
the parasite to mature to an infective stage. If the mosquito was
made to lay more eggs, it would die too early for the parasite to
mature, again breaking the transmission cycle.
02.58 SOT :Professor Hilary Hurd -
“If we can understand more about the biology and
particularly the molecules involved and that are critical to
maintaining the cycle then we can try to interfere with those
molecules perhaps by manipulating the mosquito genetically so that
a key molecule is produced in more abundance or is not produced at
all and upset this delicate balance between infection and
survival.”
03.24 Researchers
at microscopes
Embryo
injected
Genetically
modified images
Guide Voice: While some researchers in Keele
University’s Centre for Applied Entomology and Parasitology,
are studying the biology of the mosquito, others are working on
this genetic engineering approach, to see if they can inhibit the
mosquito from passing on the parasite.
By injecting mosquito embryos with different genes with
fluorescent markers that show up under ultraviolet light, they can
track the genetically modified mosquitoes as they grow, and also
see where the genes go.
While they can introduce new genes, its not a precise process,
and they can’t yet predict where they might end up in a
chromosome, or whether they could damage existing genes.
03.56 SOT Professor Paul Eggleston
-“The main limitation is simply one of
efficiency, this is a very inefficient and technically demanding
procedure so we’ve been trying at Keele in the recent past to
think up new ways, new tools to get round these limitations and
inefficiencies. One way to do that is to introduce a docking site
into the mosquito chromosome. This is simply a target into which we
can integrate any new gene of our choice and we know that if the
genes go into this target site then they are going to be reliably
expressed and we also know that they are not going to have a
negative impact on any of the normal genes within the
mosquito.”
04.29 Modified
mosquitoes
Guide Voice:Their aim is to engineer a mosquito
which is simply incapable of transmitting malaria.
04.33 SOT Professor Paul Eggleston
-“What I would like to do with our new
technology is to introduce a whole suite of trans genes, novel
genes into that mosquito so we can have what I think of as a multi
hit approach. We want to be able to tackle the parasite at several
different places within the insect all at the same time to make
sure that no parasites survive and therefore we’ve
effectively broken the transmission cycle.”
04.57 Ordinary
mosquitoes
Genetically
modified Mosquito
Guide Voice: The ultimate vision is to replace
natural populations of malaria carrying mosquitoes in disease
endemic areas, with a “genetically modified Mosquito”
incapable of carrying the malarial parasite, and freeing large
sections of the world’s population from the daily tragedy of
young lives lost to this deadly disease.
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