Why Scientists Are Puzzled By This Virus

Summary

The human body hosts a vast virome, teeming with trillions of viruses that play a crucial role in maintaining our health. These bacteriophages, or phages, specialize in hunting and controlling bacterial populations, aiding in digestion, immune system balance, and even potentially combating diseases like cancer. However, some viruses can turn beneficial bacteria into harmful pathogens, causing diseases like cholera. The complex relationship between our virome and microbiome is a frontier of science, revealing potential allies within us that can manipulate our health for better or worse.

Takeaways

• 🌐 The human body is home to trillions of viruses, which are part of the human virome and play a crucial role in our health.
• 🤝 These viruses are not enemies but symbiotic partners, aiding in digestion, immune system balance, and protection against harmful bacteria.
• 🔬 Bacteriophages, or phages, are viruses that specifically target bacteria and are the most abundant type in the human virome.
• 🦠 In the gut, phages help control bacterial populations by hunting and killing bacteria, which is essential for maintaining a healthy balance.
• 🛡️ Some viruses can alter bacteria to support the host's body, such as by enhancing the gut's mucus layer or improving the breakdown of complex carbohydrates.
• 🚫 However, there's a dark side: certain viruses can turn harmless bacteria into pathogens, like the CTXφ bacteriophage with Vibrio cholerae, causing diseases.
• 🛑 The human virome can also include oncolytic viruses, which target and kill cancer cells, potentially offering a new avenue for cancer treatment.
• 🤔 The human virome is unique to each individual and is still not fully understood, with ongoing research revealing more about its complexity and importance.
• 🧬 Viruses can manipulate bacteria in ways that either support the host's health or cause harm, highlighting the delicate balance within our microbiome.
• 🌟 The potential of the human virome to combat diseases, including cancer, is an exciting frontier in science with the possibility to save millions of lives.

Q & A

What is the human virome?

The human virome refers to the collection of viruses that live in and on the human body, including bacteriophages that are specialized in hunting and killing bacteria, playing a crucial role in maintaining health.

How do viruses in the human virome contribute to our health?

Viruses in the human virome, particularly bacteriophages, help maintain a balance in the bacterial population by hunting and killing bacteria, which can prevent overgrowth of harmful bacteria and support the immune system.

What is the relationship between bacteriophages and bacteria?

Bacteriophages are viruses that infect bacteria. They can either kill bacteria by taking over their cellular machinery to replicate or integrate their DNA into the bacterial genome to remain dormant until triggered to kill the host.

How do some viruses manipulate bacteria to benefit the human body?

Some viruses can inject genes into bacteria that make them support the human body more effectively, such as by improving the gut's mucus layer, enhancing the breakdown of complex carbohydrates, or altering signals sent to immune cells to prevent allergic reactions or autoimmune diseases.

What is the potential dark side of the human virome?

Some bacteriophages can carry dangerous genes that, when integrated into bacteria, can turn harmless bacteria into harmful or even deadly pathogens, causing diseases like cholera or severe skin infections.

Can viruses in the human virome help fight cancer?

Yes, oncolytic viruses are known to target and kill cancer cells by exploiting their weaknesses against viral infections, turning cancer cells into virus production factories, and attracting immune cells to attack the tumor.

How do oncolytic viruses disrupt the cancer cell's environment?

Oncolytic viruses can disrupt the protective environment that tumors create to evade the immune system, effectively opening the gates for immune cells to attack the tumor more effectively.

What is the role of the human microbiome in our body?

The human microbiome consists of trillions of bacteria that live in symbiosis with the human body, aiding in digestion, vitamin synthesis, immune system balance, and preventing harmful bacteria from colonizing.

How do viruses in the gut virome control bacterial populations?

Viruses in the gut virome, such as bacteriophages, control bacterial populations by specifically targeting and killing bacteria, thus preventing their overgrowth and maintaining a healthy balance in the gut ecosystem.

What is the potential of oncolytic viruses in cancer treatment?

Oncolytic viruses show promise as a new tool in cancer treatment, potentially complementing chemotherapy or radiation therapy, and may become an important part of cancer treatment strategies in the future.

Outlines

00:00

🌐 The Human Virome: Guardians of Your Health

Scientists have discovered that the human body hosts trillions of viruses, which are not harmful but essential for health. These viruses, particularly bacteriophages, protect against disease and may even combat cancer. The human virome is a unique virus ecosystem that plays a symbiotic role in maintaining the balance of the human microbiome, which consists of 40 trillion bacteria that perform various beneficial functions such as breaking down meals, synthesizing vitamins, and balancing the immune system. The virome keeps bacterial populations in check, with bacteriophages specializing in hunting specific bacteria, thereby preventing overgrowth and disease. Some viruses even enhance bacterial support for the body, such as improving the gut's mucus layer or modulating immune cell signals to prevent allergic reactions and autoimmune diseases.

05:06

🦠 When Viruses Turn Bacteria into Pathogens

While the human virome is generally beneficial, some viruses can transform harmless bacteria into dangerous pathogens. For instance, the CTXφ bacteriophage infects Vibrio cholerae, integrating the cholera toxin gene into the bacteria's genome, causing severe diarrhea and dehydration. Similarly, the φSa3ms phage can arm Staphylococcus aureus with superantigens and enzymes that break down the body's defenses, leading to a highly aggressive infection. These examples illustrate the dark side of the virome, where viruses can enhance the virulence of bacteria, making them formidable threats to human health.

10:08

🛡️ Cancer-Killing Viruses: A New Frontier in Medicine

Oncolytic viruses, which target and destroy cancer cells, represent a promising area of medical research. Viruses like the Newcastle Disease virus and Reovirus primarily infect and kill tumor cells, exploiting the cancer cells' weakened defenses against viral infections. These viruses not only kill cancer cells but also disrupt the protective environment that tumors create to evade the immune system. By doing so, they attract immune cells to the tumor site, enhancing the body's natural defense against cancer. The potential integration of oncolytic viruses with chemotherapy or radiation therapy could revolutionize cancer treatment, offering a new weapon in the fight against this deadly disease.

Keywords

💡Virome

The human virome refers to the collection of viruses that live in and on the human body, particularly in the gut, skin, saliva, and other body fluids. In the video, the virome is depicted as a symbiotic ecosystem that plays a crucial role in human health by controlling bacterial populations and potentially even fighting diseases like cancer. The video emphasizes that while the presence of trillions of viruses might seem alarming, they are not enemies but rather allies that contribute to maintaining a healthy balance within our bodies.

💡Bacteriophages

Bacteriophages, or phages, are a type of virus that specifically infects bacteria. They are highlighted in the video as the majority of the human virome, with around 97% of the gut's viruses being bacteriophages. These viruses are not harmful to human cells but are essential in controlling bacterial populations by hunting and killing specific bacteria. An example from the script is the Lambda Phage, which targets Escherichia coli, a bacterium that can be both beneficial and harmful depending on its environment within the body.

💡Microbiome

The human microbiome is the community of microorganisms, including bacteria, that live in and on the human body. The video explains that these microbes have a symbiotic relationship with the human body, performing essential functions like breaking down food, synthesizing vitamins, and balancing the immune system. The microbiome and the virome are interconnected, with viruses playing a role in regulating the microbiome's composition and activity.

💡Oncolytic Viruses

Oncolytic viruses are a special class of viruses that have the ability to infect and destroy cancer cells. The video suggests that these viruses could be a promising tool in cancer therapy, as they can exploit the weaknesses of cancer cells to replicate and kill them from within. This not only destroys the cancer cells but also attracts the immune system's attention, potentially enhancing the body's natural defense against tumors.

💡Ecosystem

The term 'ecosystem' in the video is used to describe the human body as a complex environment that supports a vast array of living organisms, including bacteria and viruses. This ecosystem is characterized by a delicate balance, where each organism, including the trillions of viruses, plays a role in maintaining the health of the whole system. The video uses the ecosystem analogy to illustrate the interdependence and mutual influence among the different components of the human body's microbial and viral communities.

💡Immune System

The immune system is the body's defense mechanism against harmful pathogens and foreign substances. In the context of the video, the immune system is shown to have a complex relationship with the virome and microbiome. While it is designed to protect the body from infections, the video suggests that some viruses can actually help regulate the immune system, preventing allergic reactions and autoimmune diseases by altering the signals that bacteria send to immune cells.

💡Cholera Toxin

The cholera toxin is a poisonous substance produced by certain strains of the Vibrio cholerae bacteria, which can cause severe diarrhea and dehydration leading to death if untreated. The video explains that the toxin is actually a 'gift' from a bacteriophage (CTXφ) that infects the bacteria, turning a usually harmless strain into a deadly pathogen. This example illustrates how viruses can have profound effects on the pathogenicity of bacteria within the human body.

💡Staphylococcus aureus

Staphylococcus aureus, commonly known as staph, is a type of bacteria that can live harmlessly on the skin and in the nose but can cause serious infections if it enters the body through a wound. The video discusses how a bacteriophage named φSa3ms can alter this bacteria, making it more dangerous by providing it with genes that produce toxins and enzymes that can break down the body's defenses. This highlights the dual nature of the virome, where viruses can both protect and harm human health.

💡Superantigens

Superantigens are a type of toxin that can overstimulate the immune system, causing a massive and uncontrolled release of immune cells and inflammatory chemicals. The video uses the example of a bacteriophage that can transform Staphylococcus aureus into a more dangerous pathogen by providing it with genes that produce superantigens. This can lead to a severe and potentially life-threatening immune response.

💡Cytokines

Cytokines are small proteins that are crucial for cell signaling in the immune system, particularly in the response to infections and inflammation. The video mentions cytokines in the context of how superantigens can cause an overproduction of these proteins, leading to a massive activation of the immune system and severe inflammation. This can be harmful, as it disrupts the body's ability to fight off infections effectively.

Highlights

Scientists have discovered that your body is home to trillions of viruses, which are crucial for your health.

These viruses protect you from disease and may even have the potential to kill cancer cells.

The human virome is a new frontier in science, with unique ecosystems of viruses specific to each individual.

The human body is a complex ecosystem consisting of up to 40 trillion cells and an equal number of bacteria.

Bacteria in the human microbiome perform essential functions like breaking down meals and synthesizing vitamins.

The balance between bacteria and viruses is delicate, with viruses acting as predators to control bacterial populations.

At least ten trillion viruses are present in the human body, with thousands of different species.

Bacteriophages, or phages, are viruses that hunt and kill bacteria without infecting human cells.

Viruses in the gut help control bacterial populations and prevent the overgrowth of harmful bacteria.

Some viruses can alter bacteria to support the human body, such as by enhancing the gut's mucus layer.

The human virome can influence immune responses and potentially protect against autoimmune diseases.

Certain bacteriophages can turn harmless bacteria into harmful ones by integrating dangerous genes into their genetic code.

Viruses can transform bacteria like Vibrio cholerae into deadly pathogens by providing them with genes for toxins.

Oncolytic viruses target and kill cancer cells, exploiting their weaknesses against viral infections.

Oncolytic viruses may become an important tool in cancer treatment, complementing chemotherapy and radiation.

The human virome is a vast and complex system with trillions of potential allies that can impact health in various ways.

The study of the human virome is an exciting and growing field with significant implications for human health.

Transcripts

Very recently scientists discovered that  your body is teeming with trillions of  

the most bizarre viruses – these viruses are  not your enemies but critical to your health,  

protecting you from disease, maybe even  killing cancer. A new frontier of sci 

ence, something truly new that  we are only just beginning to  

understand. Let us dive into the  wild world of the human virome.

You are an Ecosystem

You're a living, breathing ecosystem made of up  to 40 trillion cells. This metropolis of flesh is  

home to the human microbiome, another 40 trillion  bacteria that have a contract with your body:  

They get to live here and in return they  break down your meals. They synthesise  

vitamins in your gut, neutralise acid in  your mouth, help balance your immune system,  

and they take up space preventing  harmful bacteria from getting in.

This is a fragile balance – bacteria really  only look out for themselves, multiplying  

and testing their boundaries.  To keep their numbers in check,  

your body's ecosystem needs  a group of deadly predators:

Viruses. At least ten trillion.

They're literally everywhere in your body,  tens of thousands of different species.

At least a few trillion live in your gut,  where also most of your resident bacteria  

are. At least 18 billion on your skin,  100 million in each drop of your saliva,  

dozens of millions in your urinary tract.  Even in a single drop of the cerebrospinal  

fluid surrounding your nerves and brain,  researchers found up to 10,000 viruses.

While this sounds like a horrible idea at first,  

at least in the gut, around 97% of  them are bacteriophages, or phages,  

bizarre creatures that are specialised in  hunting down and killing resident bacteria  

and are not able to infect your cells. Instead  they kill trillions of bacteria every single day.

Together these viruses make up the human  virome – a symbiotic virus ecosystem that  

is completely unique to you and that seems  to be crucial for your health. Let’s get to  

know them and see how they support you  – and what happens if things go wrong.

The Silent Mass Murderers of Your Body

Inside your gut, a stealthy Lambda Phage  floats through the buzzing crowds of bacteria,  

looking for a victim. It has six legs, a long thin  body and a big head, made of geometric shapes,  

filled with genetic material. Each species is  specialized in hunting one specific species  

of bacteria and ignores all others.  Lambda is looking for Escherichia coli.

This versatile bacteria is numerous in your  gut, usually a good boy synthesising vitamins  

for you. But it also has a dark side – some of  them would much rather live inside your flesh  

and feast on your resources. If there are too  many or if they manage to invade your tissue,  

they can cause serious diseases. So one  of the most important jobs of the virome  

is to control the numbers of different  bacteria populations. By killing them.

Lambda has found a victim. Spider-like legs get  a hold of a bacteria and grip it hard. Like an  

angry syringe it violently rams its sharp bottom  into the victim’s body and releases its DNA and

Once inside, the proteins disable the  defenses of the bacterium. It is now

a factory under new management. It  is forced to build new viruses until  

the victim is filled up and bursts open,  releasing a horde of fresh Lambda viruses.

But its goal is not genocide.

Phages need a healthy population of bacteria  to survive. So sometimes they choose a way  

more sinister tactic. Instead of killing their  victim, the virus integrates its DNA into the  

genome of the bacteria and goes to sleep. When the  bacteria multiplies, the virus DNA is multiplied  

too. Until one day the viral DNA re-awakens and  suddenly decides to kill its unsuspecting victim.

And here things become exciting – your  virome also needs you to thrive. It’s in  

its best interest that you are healthy. So some  viruses inject genes into bacteria that actively  

make them support your body. Some force their  bacteria hosts to support your gut’s mucus layer,  

break down complex carbohydrates  from your food more efficiently,  

creating substances that  protect against inflammation.

And they alter what signals bacteria send to your  immune cells. Basically they’re letting them know:  

We have things under control, you  can chill out. This may prevent  

allergic reactions or even protect  you against autoimmune diseases.

But of course, there is also a dark side to  this story. Some viruses don’t care about  

our health. Instead of helping they turn  harmless bacteria into deadly monsters.

When Viruses turn Bacteria into killers

Some species of bacteriophage carry  dangerous genes for toxic substances.  

When they take over their hosts, they  can integrate into the genetic code of  

the bacteria where they lay as a deadly gift. Like the case of the Vibrio cholerae and the  

CTXφ bacteriophage hunting them. Most  strains of the cholerae bacteria are  

harmless and billions of them may live in your  gut right now. When CTXφ infect the bacteria,  

they gift them the genes for the cholera  toxin, which permanently becomes part of  

their genetic lineage forever. It's  like handing a house cat a shotgun.

Vibrio cholerae shower these toxins at the  cells lining your gut, making them sick. They  

vomit large amounts of salt, which pulls out  a flood of water into your intestines. This  

causes explosive diarrhoea and vomiting,  draining your body of fluid. If untreated,  

about half of patients die. But for the  phage and bacteria this is great. They are  

carried out of the body to infect more humans,  spreading and multiplying further. This strain  

of Vibrio cholerae is now a dangerous  enemy of humanity thanks to this virus.

Or the bacteria Staphylococcus aureus, which is  hunted by the phage with the amazing name: φSa3ms.

Usually the bacteria is mostly harmless  and lives on your skin and inside your  

nose. It doesn’t do anything useful per  se, its main job is to take up space,  

making it harder for hostile bacteria to  colonise your body. But φSa3ms can change this  

quickly – it carries multiple dangerous genes,  like giving a cat flamethrowers and grenades.

If such a modified Staphylococcus aureus  bacteria gets into your body through a tiny cut,  

it becomes extremely dangerous. One of its new  weapons are superantigens, which basically is  

like injecting your immune cells with cocaine.  The toxin completely breaks your carefully fine  

tuned immune system. It activates all of your  T cells, all at once and makes them flip out.  

They release a tsunami of cytokines, activating  all of your defenses at once. The infection is  

flooded with cells that can’t fight the  bacteria and cause heavy inflammation.

Your broken and confused immune cells have a  really hard time fighting Staphylococcus aureus,  

which now invades, penetrating deep into your  tissue. Your body is trying to seal the wounds  

and isolate the invader, but another new  weapon it gained has the ability to just  

dissolve the barriers and penetrate even deeper.  Before the onset of antibiotics an infection  

with Staphylococcus aureus was very deadly and we  have φSa3ms to thank for making it even deadlier.

But the viruses of our virome may also  directly save your life – by killing cancer.

Cancer Killing Viruses

Oncolytic viruses specialize in hunting and  killing cancer – like the Newcastle Disease  

virus or the Reovirus, who mostly ignore your  healthy cells and instead hunt down tumors.  

Cancer cells are broken mutants that evolve  various ways to hide and fight back against  

your immune system. But as they get better  at this, they get worse at other things,  

like fighting back viruses. A weakness to  be exploited. Oncolytic viruses target the  

specific adaptations of cancer cells, hitting  them where they are not ready to be hit.

And worse for these cells, since their  internal machinery is compromised,  

they can’t defend themselves. They are taken  over and turned into virus production factories.  

Eventually the new viruses leave the cancer cell,  often killing it, and carry on infecting other  

cancer cells nearby. This death and destruction  is not subtle, and one side effect is that  

it attracts immune cells that immediately  begin attacking the tumor with full force.

What is even more impressive, these  viruses seem to disrupt the artificial  

environment that tumors create to keep  your immune system at bay. Oncolytic  

viruses are like infiltrators in a city  at siege, opening the gates while killing  

defenders left and right – helping  your immune cells to win the fight.

In 2024 we don’t know yet to what degree oncolytic  viruses are part of your virome or more of a happy  

accident. But they seem to go well together with  chemotherapy or radiation. Eventually they may  

become an important new tool to enable us to  eliminate cancer and save millions of lives.

We don’t know what we will learn in the  next few years, but we now know that there  

are trillions of potential allies within  us, killing and manipulating, for better  

or worse. What an exciting time to be alive.

Well, that was an interesting ride! Are there  

any more exciting stories? Enter our friends  from Imprint! Their app is a unique new way of  

learning concepts and ideas in a beautifully  visual, bite-sized and interactive way.

If you’re like us, you’re easily caught up in  scrolling mindlessly. Watching more videos.  

scrolling on social media... watching more  videos... – ehem. Imprint gives you an outlet  

that actually makes you feel good about your  screentime. Their library offers lessons on  

all kinds of topics like psychology, history,  philosophy, finance, productivity and more,  

spanning from quick reads that take you  two minutes to run through to 80 unit full  

lesson courses that you can complete in only 5  minutes per day as you embark on a multi-week  

learning journey. Based on the latest science  of learning, Imprint uses a beautifully animated  

and highly interactive approach to learning  to help you retain what you learn AND enjoy  

the process. We can see why it’s been named  Google’s App of the Year – honestly it’s  

the best way to build a life of learning by  turning to it whenever you are waiting in line,  

on public transport or just feel  like having a moment to yourself. 

If you want to support kurzgesagt and invest  in your mind with just a few minutes each day,  

go to the link: imprintapp.com/Kurzgesagt  to start your 7-day free trial and get  

20% off an annual membership.

The latest limited edition pin is here –

coming to you straight from the  Ducktopia Labs. It’s the Determinator 3000.

Does free will exist? Are you in charge of your  own life and free to make your own decisions? 

Do you even want to be in  charge of your own life? Or  

do you sometimes wish that some of your  daily decisions could be made for you? 

We thought so. That’s why we  created the Determinator 3000.

It uses highly advanced supertechnology to  analyze any query and calculates the best  

course of action for you. (Probably.) And what’s even better: by obeying its  

command you will put the question of  free will to rest – once and for all.

This very special limited edition pin  is available for only 72h. So head over  

to the shop and pre-order now! It’s the last  decision you’ll ever have to make on your own.

Add it to your collection or start a  new one. We will reveal the next Pin  

in the Ducktopia Collection as soon  as the Determinator 3000 tells us to.

Spin at your own discretion.