Transcribed from the video below:
Usually, an immune response will eradicate a threat within a few days. It won't always stop you from getting ill, but that's not it's purpose. It's actual job is to stop a threat from escalating to dangerous levels inside your body. And, through constant surveilance over time, the immune system provides another benefit. It helps us develop long-term immunity.
When B and T cells identify antigens, they can use that information to recognize invaders in the future. So, when a threat revisits, cells can swiftly deploy the right antibodies to tackle it, before it affects any more cells. That's how you can develop immunity to certain diseases.
The next time you catch a cold or scratch a mosquito bite, think of the immune system. We owe it our lives.
How does your immune system work?
There can be as many as 10 million ribosomes in a human cell!
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Virus infection and how the immune system stops it
The immune system can fight a virus multiple ways:
- Antibodies may interfere with virus binding to receptors.
- Antibodies may interfere with the uptake of bound virus into the cell.
- Antibodies may prevent the release of the virus' genetic material during the uncoating phase in the endosome.
- Antibodies can form aggregated virus particle clusters.
When a vertebrate is infected with a virus, antibodies are produced against multiple epitomes (recognizable bits of protein sequence) on multiple virus proteins. A subset of these antibodies can block virus infection by a process that is called neutralization. (Basically, breaking up the virus particles into pieces and getting rid of the trash that is left)
Your questions in detail
When the immune system fights a virus, antibodies bind to the virus that stop it replicating.
As you can see in the image and the text above, antibodies don't always bind to just the virus. Sometimes it binds somewhere else to stop the virus from doing so.
Does the virus remain forever in your body, but it just cannot do anything?
Usually not, unless we're talking viruses like HIV, there are plenty of antibodies that start and help along the neutralization of virus particles.
Once an antibody has bound, does this mean the virus cannot be transmitted?
Processes in your body, typically move very fast. By the time you would notice a virus has bound to a cell or an antibody, the next process in the chain will already have taken place. In the example illustrated, the virus would either have gone into the cell to start replication or be bound by the antibodies to get removed. Also, there is one virus particle in the picture, but even at "body speed", your immune system can't clear out all the viruses immediately.
Can it be transmitted? That depends on if there is any free virus left and the type of virus. If it is in your saliva and the virus is respiratory in nature, chances are it will spread when you sneeze. Ebola will still spread if people interact with your body fluids.
The risk of transmission is gone when ALL virus particles have been neutralized, not just some of them.
Source
First, let’s start with what antibodies actually do. They can do any of the following upon binding to the virus.
- Opsonization, which is a fancy word for making the virus more delicious to white blood cells so they’re more likely to attack and eat it.
- Aggregation. Antibodies are Y shaped. The bottom of the bottom of the Y (the Fc) is the delicious part. The two other prongs of the Y are identical and are “sticky” to very, very specific parts of a given virus. The same Y-shaped antibody can thus stick to more than one virus, and if it sticks to enough they form a ball that is delicious to white blood cells and is too big and unwieldy to really infect anything. This is an oversimplification but fine for our purposes.
- Blocking binding sites. Viruses can’t move on their own and are reliant on bumping into host cells in such a way that their binding sites hit the appropriate binding site on a host cell. If the viral binding partner is bound by an antibody, the virus is neutralized because it can’t bind a host (note that the virus may have multiple binding sites).
- The antibodies trigger the complement system which neutralizes the virus. The complement system basically rips a hole in target pathogens without help from white blood cells. In the cases of viruses its slightly trickier, but broadly speaking the complement system kills pathogens before white blood cells eat them.
- Antibodies can also interfere in other ways, such as preventing uncoating (the release of the virus's genetic material which is a necessary step for infection), but these are the main things that happen.
I went into this much detail because your premise was incorrect. Antibodies binding to viruses do not necessarily stop them from replicating. It’s kind of like saying that shooting a lion stops it from hunting. It can if it kills it, but that’s not the only possible outcome. Likewise a bound virus can still infect a cell if it hasn’t been neutralized by other aspects of the immune system and it isn’t bound in an ideal place.
For example, here’s a model of the flu virus.
As you can see, it has a portion of its outer membrane (more accurately, its viral envelope) that binds to sialic acid receptors on cells. It doesn’t just have one of these - it has many. Recall that the virus has no way of moving on its own - it’s just reliant on dumb luck to bump into the right cell. The more binding sites it has, the better its chances of bumping into the right cell in the right way. (As a side note, a typical virus is MUCH smaller than a typical human cell - this picture is not to scale). Remember that you’re looking at a cross-section of the virus, too - it’s actually shaped like a ball and has those receptors all over it. A single antibody attachment is not going to stop it from infecting a host cell unless:
- That antibody caused a white blood cell to eat the virus before the virus bumped into a host cell.
- The antibody happened to be blocking the exact receptor that bumped into the host cell (or else just happened to be positioned properly to prevent the virus from getting into the host).
- The antibody successfully triggers the complement system, neutralizing the virus.
- The single antibody manages to bind another virus as well, starting off aggregation.
Now, on to your questions.
It should be clear now how viruses are neutralized by antibodies (and of course that a virus that has not been neutralized can still be transmitted). What happens to a virus assuming that it’s been neutralized? White blood cells eat it, break it down into pieces, and put some of those pieces on special receptor complexes as a sort of ‘sign’ that warns the immune system that if it sees these specific parts, go attack it - it’s a pathogen.
Note that certain types of viruses called retroviruses have the ability to hide their DNA inside of your DNA. Even if all of the virus itself has been cleared, that DNA can remain inside of your DNA for literally decades. That’s why HIV is so hard to cure - even if you killed every single viral particle, a random cell of yours that was infected at some point may be triggered to read that part of its DNA and start producing HIV viruses. How do we scan every single cell’s DNA without killing them to ensure that we’ve cleared out the HIV? Figure that out and you’ll win a Nobel Prize, my friend.
Hope this helps!
When antibodies bind to something, they act as a powerful signal to the immune system to destroy that thing. In particular, cells like macrophages become highly active at grabbing on to the antibodies that are stuck to the agent, ingesting the whole glob, and destroying it in their acidic vacuoles.
When Antibodies bind to a virus, they are responsible for the production of signals which cause the cells of immune system like Macrophages to phagocytose the virus. After endulfment, the macrophages enclose the virus within endosomes which secrete various proteolytic enzymes causing degradation if the virus.
https://www.quora.com/How-do-antibodies-kill-viruses
There are a number of ways. Assuming I take the broader definition of kill.
In short antibodies either prevent infection or signal to other cell types.
Firstly, they can prevent infection if say they bind to a receptor critical for cellular invasion. Thus they prevent cell/virus contact and the virus is neutralised.
Secondly, antibodies are useful in fighting virus as they coat the virus in essentially a tag that allows other immune cells to recognise it as foreign material and subsequently remove it. although some viruses use this as a method to gain entry into a cell. So it is not always effective.
antibody | Definition, Structure, Function, & Types
Antibodies by themselves do not kill viruses.
In contact with an infectious organism, SOMETIMES the bodies immune system makes things that are parts that attach to parts of the infectious organism. (Create molecules that then attach to an infectious organism)
They are like flags that say “kill me”
Then…… other parts of the immune system know what to attack and get rid of.
How that happens, of course is very complicated.
Our body performs miracles every day, we are not aware of, or even understand how it happens.
Even though we do create a lot of antibodies, for say viruses, things like herpes, chicken pox and other viruses, the body is not able to get rid of completely.
Then the immune system just keeps in in check, but when sick or run down they reemerge again. Some viruses like that and also HIV or other viruses can cause cancer or immune system problems as the body can not get rid of them completely.
For most bacteria and viruses, fungus parasites, the body has a current library, but then it wears off.
Like having magazines in periodicals.
If the body hasn't been exposed or had it in a long time it might have worn off and not have many circulating antibodies or memory.
It works VERY well generally, in most healthy people to deal with and keep us safe from most general things we are exposed to on a day to day basis.
Some organisms or parasites, even with a healthy state, are infectious and dangerous, and set into the system and not easy to get rid of.
https://www.quora.com/How-is-it-that-the-Covid19-virus-is-relatively-easy-to-kill-on-an-outside-surface-but-nearly-impossible-once-it-enters-our-bodies
Virology: When a virus enters a human body, is it sure that it will infect the individual? If no, then how will our immune system fight it out?
Viruses have little control where they go once they leave their host. You are constantly being inundated by viruses, both from other humans, and from all the species around you -- dogs, cats, cockroaches, African violets, bacteria, amoeba, everything. And of course you are not constantly being made sick, even by the human viruses, let alone the dog or African violet viruses.
Viruses usually don't cross species very well. Even viruses that can infect multiple species are often more specialized for one or another. (There are a handful of exceptions that can infect many species, like rabies.)
There are too many reasons to go into all of them in any kind of details. Basically, a virus needs to be pretty fine tuned to the specific cell proteins. All the things a virus has to do -- enter a cell, replicate its proteins, assemble new visions, exit the cell -- all these things are built on interactions with the host cell proteins, and in many cases even a tiny change in the host cell protein completely blows out the virus's ability to interact with them.
(And of course, even closely related species, like humans and chimps, have significant differences between many of their proteins.)
Two of the most common barriers to interspecies infections are host entry and cell survival.
Viruses tend to enter cells by first binding to some surface molecule, and this binding has to be pretty precise. It's unusual to have enough similarity between two species for this entry step to work perfectly.
Most cells have built-in defenses against virus infection (viruses have been around for a long, long time, and driven a great deal of natural selection). One of the common forms of defenses in multicellular species is cell suicide. When the cell recognizes that it's been infected, it simply dies, preventing the virus from completing its replication cycle. Accordingly, most viruses have methods to block this cell suicide. But because the suicide pathways tend to be complex and redundant and to evolve rapidly (because this is an arms race with viruses), it's really hard for a virus to effective block all the pathways in more than one species.
I haven't even gotten into immunity yet, but you can see that immunity almost isn't necessary for many of these interspecies infections; the virus isn't capable of getting to the point where the immune system needs to bother. (Although the cell suicide pathways hook in to immunity very closely, and often large chunks of these pathways are considered part of the immune system, so it's a bit of a definition thing.)
No. Viruses do not infect the host (individual) always. Actually more often than not they are destroyed.
Our immunity is divided into innate (inborn) and adaptive immunity. Adaptive immunity takes charge once it is identified that individual is under attack of an offending organism (virus, bacteria etc).
Adaptive immunity has several modes of working; two commonest are B Lymphocytes and T Lymphocytes. B cells produce antibodies, which destroy the organisms. T cells also known as killer cells directly destroy the offending organisms. T cells work in one the following ways:
- they kill virus-infected cells
- they activate interferon, which inhibits replication of virus
- they activate other cells that kill virus-infected cells
The major defense against virus-infected cells is the CD8+ T-cell.
At times both the systems ( B & T) work together.
I hope it is simplified enough to understand.
Antibodies cannot “kill viruses,” per se. Viruses cannot be killed because they aren’t living; they lack the mechanisms to reproduce on their own. However, vaccines that contain antibodies or aptamers can inhibit the binding of viruses to cells, thus preventing them from entering the cells and replicating using the host cell’s machinery.
You wake up in the morning and instantly you know something’s wrong. You’re feverish, you ache all over, and you’re afraid you’re going to be sick to your stomach.
You hope you’re not coming down with something! After a few more grueling days of fighting it, you finally admit that it’s time to see the doctor - maybe he can give you a pill or something that will kill this virus.
The next day at your doctor’s office, you describe the overwhelming exhaustion you feel, the blinding headache you’ve had for days, and the aching pain all over your body.
Flushing with embarrassment, you also tell him about the more… icky symptoms you’ve been experiencing, like the vomiting, cramps, and diarrhea that has had you practically living in the bathroom between bouts of restless, feverish sleep.
“I’m desperate, Doc”, you say. “Is there a pill or an antibiotic or something I can take?” To your dismay, he shakes his head and says: “Unfortunately, an antibiotic won’t do anything to help you.
We’ll take blood and urine samples and run a culture test to be sure, but it sounds to me like you have a viral infection, and unfortunately, antibiotics don’t work on viruses.”
How Virus and Bacteria are different things?
This is news to you, so your doctor patiently explains to you exactly what a virus is, and how viral infections - like the one you apparently have - are different from bacterial ones. Viruses and bacteria are both microbes - tiny organisms that are too small to see with the naked eye.
Viruses are much smaller than bacteria - the largest virus is smaller than the tiniest bacteria - and it takes a powerful microscope to be able to observe these tiny intruders.
Both bacteria and viruses spread through contact with infected people, animals, surfaces or food, and both can cause symptoms like yours - digestive upset, muscle, and joint pain and respiratory distress.
Bacteria
But the similarities end there. Bacteria are single-celled creatures that can reproduce on their own and can survive in a huge variety of environments, living comfortably in extreme heat or cold, in radioactive waste, and even in the human body.
The fossil record shows that bacteria have been thriving on earth for more than three-and-a-half billion years. Most bacteria are harmless to us, and many are actually helpful. For example, certain strains of bacteria thrive in our digestive system where they help us break down food - no wonder probiotic yogurt has been all the rage lately.
Trillions of bacterial microorganisms live in our bodies, making themselves at home in our digestive system, on our skin and even in our eyes and nose! In fact, according to Meghan Jardine, Associate Director of Diabetes Nutrition Education at Physicians Committee, we might actually be “only ten percent human. Ninety percent of our cells are nonhuman, microbial cells.”
In recent years, scientists have put this number at closer to forty percent human cells - but that’s still pretty crazy when you think about it! Although less than one percent of all bacteria are actually harmful to people, the ones that do cause diseases can do some serious damage.
Bacteria give off toxic chemicals that can damage human tissue and make us sick. The most dramatic example of a bacterial infection is the bubonic plague in Europe in the thirteen hundreds.
As the plague spread, people throughout Europe were coming down with fevers and chills, vomiting and diarrhea, and aches and pains. They also had nasty black boils that oozed blood and pus - a gruesome symptom that earned this plague the name The Black Death.
We now know that the infection was caused by a bacteria called Yersinia pestis, but of course, people knew nothing about that in the fourteenth century.
By the time the plague subsided, it had killed an estimated twenty million people - a third of the entire population of Europe at the time. Since precise numbers are hard to come by, the death toll could have been much higher - some experts estimate that up to sixty percent of the population was wiped out by a tiny, single-celled bacteria.
Thankfully, we can now treat bacterial infections with antibiotics, which kill the bacteria causing the infection or at least slow its growth.
Antibiotics are a fairly recent discovery - the first antibiotic was used in nineteen thirty-six, and it wasn’t until the late eighteenth century that a German doctor named Robert Koch even discovered that bacteria caused diseases.
In the year nineteen hundred, before the invention of antibiotics, nearly thirty percent of all deaths worldwide could be blamed on bacterial infections that can be easily treated with antibiotics today.
Virus
Viruses are much more fragile than bacteria. The virus’s core of genetic material is protected only by a thin protein coating.
A virus can’t survive without a host, and can only reproduce by attaching itself to a host cell and inserting its genetic material into it.
Unlike bacteria, nearly all viruses cause diseases in humans. Viruses are usually programmed to target specific cells before it gets to work either replicating itself - making new viruses until the host cells burst and die - or turning normal, healthy cells into malignant ones.
Viruses are responsible for a lot of common diseases. Everything from the common cold and flu to painful conditions like the chickenpox and shingles, to serious infectious diseases like hepatitis and herpes, are all caused by viruses.
The nineteen-eighteen Spanish Flu was the deadliest pandemic in history, and it was all caused by a microscopic virus. By the time the outbreak ended in nineteen nineteen, nearly one-third of the entire global population had been infected, and as many as one hundred million people had died - three percent of the world’s population.
During the outbreak, the average life expectancy in America dropped by nearly twelve years in the course of a single year, and in 1918 more U.S. soldiers died of the flu than in combat, which is shocking considering that America was in the middle of World War One at the time.
You thank your doctor for educating you and correcting your misconceptions, but there’s still something that doesn’t make sense to you. “I don’t get it, Doc,” you say. “I got my flu shot this year, so how did I end up still getting sick?” “That’s a great question, actually,” he replies.
He goes on to explain why getting the flu shot doesn’t always guarantee that you won’t get sick. The flu shot isn’t always effective in part because there is no one single virus that’s responsible for the flu, and because viruses are constantly mutating and changing.
Vaccines are developed for the most common and most serious strains of the flu virus, but it’s impossible to predict which strains will hit in any given year, and it takes time to produce a vaccine after a new strain becomes problematic.
Even if you got the right flu shot for the right strain, you can still get sick if your body’s response to the virus isn’t fast enough or strong enough, which can happen to older people, those with suppressed immune systems, or anyone who’s had significant exposure to the virus.
Vaccines work by exposing your body to antigens, parts of an inactive version of the virus, training your immune system to release antibodies and quickly and aggressively attack the virus before it can spread. “Wow,” you say. “I had no idea how cool vaccines are! Thanks for explaining to me.
But Doc, now that I have the virus, how do I kill it!” It turns out, there are lots of ways to kill a virus. Antiviral drugs exist to treat conditions like herpes and hepatitis.
They work by interfering with an enzyme in the virus and preventing it from leaving one cell to infect another, but they don't destroy the actual virus itself. One of the most exciting developments in virus-fighting technology is the use of lasers!
Continue reading Iynk.in: Most Effective Way To Kill A Virus
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