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TED-Ed, How do viruses jump from animals to humans? - Ben Longdon

How do viruses jump from animals to humans? - Ben Longdon

At a Maryland country fair in 2017,

the prize pigs were not looking their best.

Farmers reported feverish hogs with inflamed eyes and running snouts.

But while fair officials worried about the pigs,

the Maryland department of health was concerned about a group of sick fairgoers.

Some had pet the pigs, while others had merely been near their barns;

but soon, 40 of these attendees would be diagnosed with swine flu.

More often than not, sick animals don't infect humans.

But when they do, these cross-species infections,

or viral host jumps,

have the potential to produce deadly epidemics.

So how can pathogens from one species infect another,

and what makes host jumps so dangerous?

Viruses are a type of organic parasite infecting nearly all forms of life.

To survive and reproduce, they must move through three stages:

contact with a susceptible host, infection and replication,

and transmission to other individuals.

As an example, let's look at human influenza.

First, the flu virus encounters a new host

and makes its way into their respiratory tract.

This isn't so difficult, but to survive in this new body,

the virus must mount a successful infection

before it's caught and broken down by an immune response.

To accomplish this task,

viruses have evolved specific interactions with their host species.

Human flu viruses are covered in proteins

adapted to bind with matching receptors on human respiratory cells.

Once inside a cell, the virus employs additional adaptations

to hijack the host cell's reproductive machinery

and replicate its own genetic material.

Now the virus only needs to suppress or evade the host's immune system

long enough to replicate to sufficient levels and infect more cells.

At this point, the flu can be passed on to its next victim

via any transmission of infected bodily fluid.

However, this simple sneeze also brings the virus in contact with pets,

plants, or even your lunch.

Viruses are constantly encountering new species and attempting to infect them.

More often than not, this ends in failure.

In most cases, the genetic dissimilarity between the two hosts is too great.

For a virus adapted to infect humans,

a lettuce cell would be a foreign and inhospitable landscape.

But there are a staggering number of viruses circulating in the environment,

all with the potential to encounter new hosts.

And because viruses rapidly reproduce by the millions,

they can quickly develop random mutations.

Most mutations will have no effect, or even prove detrimental;

but a small proportion may enable the pathogen to better infect a new species.

The odds of winning this destructive genetic lottery increase over time,

or if the new species is closely related to the virus' usual host.

For a virus adapted to another mammal,

infecting a human might just take a few lucky mutations.

And a virus adapted to chimpanzees,

one of our closest genetic relatives, might barely require any changes at all.

It takes more than time and genetic similarity

for a host jump to be successful.

Some viruses come equipped to easily infect a new host's cells,

but are then unable to evade an immune response.

Others might have a difficult time transmitting to new hosts.

For example, they might make the host's blood contagious,

but not their saliva.

However, once a host jump reaches the transmission stage,

the virus becomes much more dangerous.

Now gestating within two hosts,

the pathogen has twice the odds of mutating into a more successful virus.

And each new host increases the potential for a full-blown epidemic.

Virologists are constantly looking for mutations

that might make viruses such as influenza more likely to jump.

However, predicting the next potential epidemic is a major challenge.

There's a huge diversity of viruses that we're only just beginning to uncover.

Researchers are tirelessly studying the biology of these pathogens.

And by monitoring populations to quickly identify new outbreaks,

they can develop vaccines and containment protocols to stop these deadly diseases.

How do viruses jump from animals to humans? - Ben Longdon ||вирусы||||||| ||Viren|||||||Longdon |||||||||Longdon Wie springen Viren von Tieren auf Menschen über? - Ben Longdon ¿Cómo saltan los virus de los animales a los humanos? - Ben Longdon Comment les virus passent-ils de l'animal à l'homme ? - Ben Longdon Come fanno i virus a passare dagli animali all'uomo? - Ben Longdon ウイルスはどのようにして動物からヒトに感染するのか？- ベン・ロングドン Kaip virusai iš gyvūnų persikelia į žmones? - Benas Longdonas Jak wirusy przenoszą się ze zwierząt na ludzi? - Ben Longdon Como é que os vírus passam dos animais para os humanos? - Ben Longdon Как вирусы переходят от животных к человеку? - Бен Лонгдон Virüsler hayvanlardan insanlara nasıl geçer? - Ben Longdon 病毒是如何从动物传播到人类的？ - Ben Longdon 病毒如何從動物傳染給人類？ ——本·朗登

At a Maryland country fair in 2017, |||land|beurs| На ярмарку в Меріленді в 2017 році

the prize pigs were not looking their best.

Farmers reported feverish hogs with inflamed eyes and running snouts. ||лихорадочных|||||||носов ||fiebrige|Schweine||||||Schnauzen Фермеры сообщили о лихорадочных свиньях с воспаленными глазами и текущими рылами. Фермери повідомили про лихоманкових свиней із запаленими очима та бігаючими мордами.

But while fair officials worried about the pigs, Но пока чиновники ярмарки беспокоились о свиньях,

the Maryland department of health was concerned about a group of sick fairgoers. ||||||||||||посетителей ярмарки ||||||||||||Messebesucher ||||||||||||bezoekers van de beurs ||||||||||||フェアの来場者 мэрилендское министерство здравоохранения беспокоилось о группе больных посетителей ярмарки.

Some had pet the pigs, while others had merely been near their barns; ||||||||||||Scheunen Sommigen||de varkens aa|||||||||| Деякі гладили свиней, а інші просто були біля своїх сараїв;

but soon, 40 of these attendees would be diagnosed with swine flu. |||||||||свиного| ||||Teilnehmer|||||Schweine-|Grippe але незабаром у 40 із цих відвідувачів буде поставлено діагноз «свинячий грип».

More often than not, sick animals don't infect humans. |||||||infizieren|

But when they do, these cross-species infections,

or viral host jumps,

have the potential to produce deadly epidemics. ||||||Epidemien

So how can pathogens from one species infect another,

and what makes host jumps so dangerous? |||хозяин|||

Viruses are a type of organic parasite infecting nearly all forms of life. ||||||паразит|||||| ||||||Parasit|infizieren|||||

To survive and reproduce, they must move through three stages:

contact with a susceptible host, infection and replication, |||||||Replikation контакт із сприйнятливим господарем, інфекція та реплікація,

and transmission to other individuals.

As an example, let's look at human influenza. |||||||influenza Як приклад розглянемо людський грип.

First, the flu virus encounters a new host Спочатку вірус грипу зустрічає нового господаря

and makes its way into their respiratory tract. ||||||дыхательных| |maakt||||||kanaal і потрапляє в їхні дихальні шляхи.

This isn't so difficult, but to survive in this new body,

the virus must mount a successful infection ||moet||||

before it's caught and broken down by an immune response.

To accomplish this task,

viruses have evolved specific interactions with their host species.

Human flu viruses are covered in proteins

adapted to bind with matching receptors on human respiratory cells. адаптированный||||||||| пристосований для зв'язування з відповідними рецепторами на дихальних клітинах людини.

Once inside a cell, the virus employs additional adaptations Потрапляючи в клітину, вірус використовує додаткові адаптації

to hijack the host cell's reproductive machinery |похитить|||||машину ||||Zelle|| |hijack||||| щоб захопити репродуктивний механізм клітини-господаря

and replicate its own genetic material.

Now the virus only needs to suppress or evade the host's immune system ||||||||umgehen||Wirts|| ||||||||evade|||| Тепер вірусу потрібно лише придушити або уникнути імунної системи господаря

long enough to replicate to sufficient levels and infect more cells.

At this point, the flu can be passed on to its next victim

via any transmission of infected bodily fluid.

However, this simple sneeze also brings the virus in contact with pets, Однак це просте чхання також приносить вірус контакту з домашніми тваринами,

plants, or even your lunch.

Viruses are constantly encountering new species and attempting to infect them. |||встречая||||||| Віруси постійно зустрічаються з новими видами і намагаються їх заразити.

More often than not, this ends in failure.

In most cases, the genetic dissimilarity between the two hosts is too great. |||||Ungleichheit||||||| У більшості випадків генетична відмінність між двома господарями занадто велика.

For a virus adapted to infect humans,

a lettuce cell would be a foreign and inhospitable landscape. ||||||||негостеприимный| |Salat|||||||| Eine Blattsalat-Zelle wäre eine fremde und unfreundliche Landschaft. клітина салату була б чужим і негостинним краєвидом.

But there are a staggering number of viruses circulating in the environment, ||||поразительное||||||| Aber es gibt eine erstaunliche Anzahl von Viren, die in der Umwelt zirkulieren, Але в навколишньому середовищі циркулює приголомшлива кількість вірусів,

all with the potential to encounter new hosts. alle mit dem Potenzial, neue Wirte zu begegnen.

And because viruses rapidly reproduce by the millions,

they can quickly develop random mutations.

Most mutations will have no effect, or even prove detrimental; ||||||или||оказаться|вредным |||||||||有害な Більшість мутацій не матимуть ефекту або навіть виявляться згубними;

but a small proportion may enable the pathogen to better infect a new species. |||||||патоген|||||| але невелика частка може дозволити патогену краще інфікувати новий вид.

The odds of winning this destructive genetic lottery increase over time, шансы|||||||||| |||||破壊的な||||| Шанси виграти в цій руйнівній генетичній лотереї з часом зростають,

or if the new species is closely related to the virus' usual host.

For a virus adapted to another mammal,

infecting a human might just take a few lucky mutations.

And a virus adapted to chimpanzees,

one of our closest genetic relatives, might barely require any changes at all. один із наших найближчих генетичних родичів, може майже не потребувати будь-яких змін.

It takes more than time and genetic similarity

for a host jump to be successful.

Some viruses come equipped to easily infect a new host's cells,

but are then unable to evade an immune response. но||||||||

Others might have a difficult time transmitting to new hosts.

For example, they might make the host's blood contagious, ||||||||заразной ||||||||感染性の Наприклад, вони можуть зробити кров господаря заразною,

but not their saliva.

However, once a host jump reaches the transmission stage,

the virus becomes much more dangerous.

Now gestating within two hosts, |развиваясь||| |Jetzt in zwei||| |妊娠中||| Jetzt, der sich in zwei Wirten entwickelt, Зараз вагітність у двох господарях,

the pathogen has twice the odds of mutating into a more successful virus. |||||||sich verändern||||| hat der Erreger doppelt so hohe Chancen, sich in ein erfolgreicheres Virus zu verwandeln. збудник має вдвічі більше шансів мутувати в більш успішний вірус.

And each new host increases the potential for a full-blown epidemic. ||||||Potenzial||||| Und jeder neue Wirt erhöht das Potenzial für eine umfassende Epidemie.

Virologists are constantly looking for mutations Virologen||||| Вірусологи постійно шукають мутації

that might make viruses such as influenza more likely to jump.

However, predicting the next potential epidemic is a major challenge. |vorhersagen||||||||

There's a huge diversity of viruses that we're only just beginning to uncover. Існує величезна різноманітність вірусів, які ми тільки починаємо відкривати.

Researchers are tirelessly studying the biology of these pathogens. ||unermüdlich|||||| Дослідники невтомно вивчають біологію цих патогенів.

And by monitoring populations to quickly identify new outbreaks, ||мониторингом|||||| І, спостерігаючи за населенням, щоб швидко виявляти нові спалахи,

they can develop vaccines and containment protocols to stop these deadly diseases. |||вакцины||сдерживание|||||| |||Impfstoffe||Eindämmung|||||| ||||||||阻止||| вони можуть розробити вакцини та протоколи стримування, щоб зупинити ці смертоносні хвороби. 他们可以开发疫苗和控制方案来阻止这些致命疾病。