Placeholder Image

字幕列表 影片播放

  • Riemsan island in the Bay of Greifswald

  • in northeast Germany.

  • It measures just 1-point-3 kilometers long

  • and three hundred meters wide

  • and is home to the oldest virological research institute

  • in the world.

  • The Friedrich Loeffler Institute.

  • The FLI is unique in Europe

  • and one of just three facilities world-wide

  • where research is carried out on large animals

  • at the highest level of biosecurity.

  • 80 different animal diseases are under investigation here,

  • including pathogens requiring

  • the strictest level of containment.

  • And those deadly germs cannot be allowed

  • to escape from the lab under any circumstances.

  • Climate change and globalization

  • are among the factors driving the advance of diseases,

  • such as the West Nile Virus spread by mosquitoes,

  • and Borna Disease.

  • Researchers work in laboratories and animals sheds

  • that are hermetically sealed off from the outdoors.

  • Working under the highest biosafety conditions, BSL-4,

  • their aim is to protect animals from deadly diseases.

  • They need to strike a delicate balance

  • between immediate animal welfare

  • and the long-term necessities of research.

  • But the impact of diseases on humans is, of course,

  • also an issue.

  • That's why the experts are doing all they can

  • to gain insights into the waysor vectors

  • via which the pathogens spread.

  • It's a battle against an invisible enemy

  • as well as a race against time.

  • In October 2020 Sandra Blome, laboratory supervisor

  • at the FLI's Institute of Diagnostic Virology,

  • received a package with extremely hazardous contents.

  • The delivery had to be handled with the utmost caution.

  • It contained tissue samples from a dead wild boar.

  • It was possible the animal had died from a plague

  • that has recently been spreading in Germany.

  • The ominous news first came in September 2020.

  • The carcass of a wild boar was discovered to the east of Berlin,

  • close to the Polish border.

  • The animal seemed to have died of a disease

  • that infects domestic and wild pigs

  • and is nearly always fatal.

  • The news came as a shock, but not as a surprise.

  • It's a virus that has been rampaging

  • in Eastern Europe for years, including in Poland.

  • Tens of thousands of domestic and wild pigs

  • had already died from it.

  • The virus was African Swine Fever, or ASF.

  • For humans: it's not a threat.

  • In Africa, ASF is transmitted by ticks from warthogs

  • and bush pigs to domestic pigs.

  • The animals become infected through direct contact,

  • mainly via the blood of infected members

  • of the same species.

  • Viruses of this kind are comprised only of a protein shell

  • and their genetic materialso from DNA or RNA.

  • They aren't able to reproduce on their own.

  • To do that, they need a living hostsuch as a pig.

  • The pathogen penetrates what is called thehost cell”.

  • Once inside, the genetic material then

  • programs the cell to produce more, new viruses.

  • The cell dies and releases thousands of pathogens

  • that go in search of new host cells.

  • Frequently, the animal can ward off the invader

  • and only becomes slightly illif at all.

  • But sometimes, the virus encounters a host

  • whose immune system is overwhelmed by the virus.

  • The disease is one among many in Africa

  • that might make warthogs and bush pigs sick

  • but not fatally so.

  • But Eurasian pigs have yet to adapt to the pathogen.

  • If an animal becomes infected,

  • it will die in practically every case.

  • The new tissue sample from the dead wild boar

  • in Germany was analyzed in the lab.

  • If it turned out to be positive for the virus,

  • that meant the disease was spreading further westward.

  • And the sample was positive.

  • The disease was on the march.

  • The virus's journey to Europe began in 2007.

  • A freighter from East Africa was heading for Georgia.

  • In the port of Poti, it unloaded meat scraps

  • at a rubbish dump.

  • Soon, more and more domestic pigs in the region

  • were becoming seriously sick.

  • And a short time later, wild boars

  • here marked in bluefell ill as well.

  • Since then the plague has spread relentlessly

  • via Russia and the Baltic states toward Western Europe.

  • In Germany, alarm bells started ringing in 2019,

  • when the first cases were detected in western Poland.

  • To prevent the virus spreading further,

  • the authorities set up electric fencing

  • near the border to keep out wild boars.

  • But by 2018, the virus had already reached Belgium

  • after seeminglyjumpingover Germany.

  • And even today, France is disease-free.

  • Humans likely made a contribution to the pathogen

  • skipping certain countries in Europe.

  • Researchers suspect that the virus spreads in food

  • because the ASF is particularly stable.

  • Even in processed pork, it can remain infectious for months.

  • But there is still no definitive proof.

  • Nevertheless, it's highly probable the disease

  • reached Belgium in just that way

  • via left-over meat transported by humans.

  • Wild boars are omnivorous

  • and don't turn their snouts up at meaty scraps.

  • And there was a conspicuously higher rate of

  • outbreaks of ASF along transregional routes.

  • In the end, the precautions failed to help.

  • African Swine Fever reached the eastern

  • German states of Brandenburg and Saxony in September ...

  • and October 2020.

  • Up to now, the disease has only spread

  • among wild boar in Germany,

  • but the risk is great that the virus will eventually infect

  • hog fattening farms.

  • An outbreak would be an economic disaster for Germany,

  • which is the world's third largest producer of pork.

  • But how can the further spread of ASF be prevented?

  • Because of a warm winter and an increase in available fodder,

  • the numbers of wild boar in Europe have mushroomed.

  • There are more than 90 thousand of them

  • in Brandenburg alone.

  • Authorities there have been relying on a radical strategy

  • to stem the tide of wild boarsvia culling ...

  • and using unconventional methods.

  • By the end of April 2020,

  • ASF had been raging for months

  • on the Polish side of the river Oder

  • which infected animals were able to cross

  • without too much trouble.

  • Egbert Gleich is a wildlife biologist

  • who works for the local authorities in Brandenburg.

  • He's also an expert in very specialhuntingtechniques.

  • The method he uses is ideally suited

  • to rapidly decimating wild boar populations

  • like the one overrunning the Oder Valley.

  • He's one of the few specialists

  • who hunt with cage traps.

  • Trapping is controversial.

  • But criticism takes a back seat

  • given the spread of the plague

  • and the unmatched effectiveness of the method.

  • Here in these areas, we want to get the wild boar

  • population down as low as possible.

  • So we've got to take measures that for now

  • essentially mean the elimination

  • of the wild boar population.

  • Thinning out the wild boar population is vital

  • in the bid to slow the spread of the virus.

  • But ultimately, ASF can only really be stopped

  • by a vaccine for wild boars and domestic pigs.

  • There have been years of research, but so far in vain.

  • The virus that causes African Swine Fever

  • is a tough and tricky foe.

  • ASF is a very large virus

  • with a very, very, complex structure.

  • The virus isas I always tell students

  • a battleship.

  • It's loaded with factors that allow it to alter

  • the immune system in favor of the virus.

  • That makes it all extremely difficult.

  • So ... Sandra Blome and her team

  • are investing their hopes in a new strategy.

  • They're using genetically altered viruses.

  • We've taken certain characteristics

  • from the viruses we're using as vaccine candidates.

  • For one, they outwit the immune system,

  • making it difficult for the immune system

  • to recognize the virus.

  • Then there arevirulence factors”, which are

  • or we hope they are

  • what ultimately makes the animal sick.

  • The pathogen that causes ASF has tools

  • that prevent the immune system from recognizing it.

  • They're called immune modulators,

  • and allow the virus to reproduce unhindered.

  • To create a vaccine,

  • the researchers are using genetically altered viruses

  • with the help of thiscamouflage”.

  • The resultafter just a short time,

  • the immune defenses recognized the altered viruses.

  • They block multiplication

  • and form immune cells and anti-bodies.

  • When the body is then confronted with genuine pathogens,

  • the immune system has learned to dodge the ruse

  • and strike back.

  • The potential vaccine has proved to be

  • very promising in the lab.

  • The next step: trials on live pigs.

  • It's the only way Sandra Blome and her team

  • can find out if the vaccine really does protect animals

  • from the virus.

  • With camera teams not allowed in the bio-secure lab,

  • the scientists filmed the experiments themselves.

  • Half of the pigs were injected

  • with the genetically altered virus.

  • A control group was left unvaccinated.

  • Three weeks later, the researchers would infect

  • the animals with the genuine

  • and up to now deadly virus.

  • Egbert Gleich has been waiting for two hours

  • to sight wild boars in the Lower Oder Valley.

  • And suddenly, they appear.

  • The morsels of grain have lured eight specimens into the trap.

  • The young animals still don't suspect a thing.

  • Now Egbert Gleich has to move fast,

  • so that their suffering is kept to a minimum.

  • It takes him less than two minutes to get from the car

  • to the trap.

  • A minute later the animals are dead.

  • This is nothunting.” It's execution.

  • But the wild boars' speedy demise

  • could save thousands of their taxonomic cousins

  • from an otherwise agonizing death caused by ASF.

  • Egbert Gleich and a colleague now check

  • whether the wild boars that have been killed

  • are indeed carrying the African Swine Fever virus.

  • They draw blood from the cadavers

  • and take the samples to the local veterinary inspection office.

  • What counts for the researchers, however,

  • is the appearance of the internal organs.

  • They indicate whether the animal was sick or not.

  • The spleen is totally flat, with normal coloring.

  • If swollen, the color would tend to be darker.

  • And here we have the kidneys.

  • Usually they're light-colored,

  • and there would be loads of little spots on them.

  • So there aren't any noticeable signs in this animal.

  • Back at the institute on Riems,

  • three weeks have gone by ...

  • Sandra Blome and her team are getting ready

  • to infect pigs, who've been vaccinated once:

  • with the real, deadly virus.

  • The virus kills almost all unprotected domestic hogs

  • after days of torment from high fever, diarrhea,

  • breathing difficulties and hemorrhaging.

  • Most of the vaccinated pigs show no symptoms

  • while the unvaccinated animals in the control group

  • become severely ill.

  • Sandra Blome has also tested vaccines on wild boars.

  • But another strategy is needed to prevent

  • the spread of the virus in the wild.

  • You can't really tell wild boars

  • that they've got an appointment to be vaccinated,

  • so we always need a vaccine

  • that can be administered orally.

  • We need a safe live virus vaccine

  • that is nevertheless effective,

  • so the genetically altered organisms