In this interactive, you will learn how the innate immune response acts against an invading pathogen. Innate immunity can help protect us from a variety of pathogens, including the coronavirus that causes COVID, though the specifics and the efficacy of the response can differ depending on the type of pathogen. While the innate immune response is able to prevent or control some infections, it is limited in the ways in which it can react.
The adaptive immune response, which includes both B cell-based humoral immunity and T cell-based cellular immunity, reacts much more specifically and powerfully to invading pathogens. B cells produce antibodies that help to control microbial invasion in a variety of ways, as described in this interactive. With your new knowledge about antibodies, you are ready to see an example of the B cell response in action.
In this interactive, the reaction of B cells to an invading pathogen is shown, including how the antibody response arises and how it is able to control the infection. While the response to a bacterial protein is shown, the steps necessary to act against viruses such as the coronavirus that causes COVID are very similar. Antibody responses are the main way in which vaccines protect us from infection by a variety of viruses, and the absence of protective antibodies contributes to the rapid spread of new viruses in previously unexposed and unvaccinated populations.
The antibodies produced by B cells form part of the adaptive immune response and can recognize almost any molecule that might invade the body. In addition, there is a second branch to the adaptive immune system called cellular immunity. T cells form the basis of cellular immunity and can very specifically kill cells that have been infected by viruses.
This video compares the two branches of the adaptive immune response, with a particular emphasis on the antiviral effects of T cells. T cells form the second branch of the adaptive immune response. For instance, you have about 25, genes, whereas HIV has eight. Viruses must also use a host cell — and all its complex machinery — in order to replicate.
But then you could say the same thing about a head louse, and we would definitely call a louse alive. So where do we begin? First of all, you have to be really clear by what we mean by alive. Some of these discussions border on philosophy, but the easiest way is to list characteristics that all living beings share. Coming up with a list that includes all recognised life forms but excludes other replicating things like fire is tricky.
However, here is a commonly used list of features that most accepted living beings share:. Humans do all these things but viruses do, at best, four of them. Viruses do not grow, metabolise or maintain a constant internal environment.
So by this definition, viruses are not alive. Viruses are the ultimate freeloaders — they sneak into our cells, eat our food and rely on our homeostasis their favourite temperature just happens to be body temperature! Have you ever wondered what exactly is in the needle when you get a vaccine, or how that works to protect you against a disease? A vaccine against a virus actually contains virus — usually either a dead, weakened, or slightly different version of the virus it protects you against.
Deliberately injecting a virus may seem like a very strange approach to preventing infections, but is a really effective strategy, because your immune system reacts to the vaccine and makes lots of specific antibodies with the right shape for the vaccine virus. The first successful vaccine was developed in against the smallpox virus, which killed about million people in the 20th century.
The vaccine was extremely good at protecting people from infection, and was given to people around the world, so that in smallpox was officially declared to be extinct. This is an amazing example of how powerful vaccines and antibodies can be in protecting us against infection. Every day you breathe in over ,, viruses. Antibodies help your immune system fight back.
What is a virus? Fascinating facts about viruses Antibodies strike back - find out how our bodies fight viruses Understanding antibodies, antigens and antibiotics Are viruses alive? Meet the Viruses - download our fact cards A4 or A6 - 2 per page What is a virus? To see a virus, it is necessary to use a scanning electron microscope, which uses electrons instead of light to produce an image. Another important fact is that there are many types of viruses. Some can just cause a common flu, while others can be more harmful such as HIV, Ebola or Coronavirus.
And, there are viruses that enter the human body, but the immune system manages to fight them, so the person does not get sick. In short, viruses can replicate and create other viruses. This is possible as they can adapt very easily to any environment and any host.
They are made to survive very difficult conditions. Usually these microorganisms enter the body through the mouth, eyes, nose, genitals or through wounds, bites or any open wounds. Moreover, they are transmitted through different routes.
Some diseases are spread by direct contact with infected skin, mucous membranes or body fluids. There is also the possibility of indirect contact, when a person touches an object door, handle, table , which has the virus on it, when an infected person sneezes, coughs or talks or when the mucous membrane comes into contact with another person. In some other cases, the virus is transmitted through common vehicle such as contaminated food, water or blood.
Finally, there are vectors: rats, snakes, mosquitoes etc. These organisms enter the body and adhere to the cell surface. Depending on the type of virus, it seeks for cells in different parts of the body: liver, respiratory system or blood. Once it has attached itself to the healthy cell, it enters it. When the virus is inside the cell, it will open up so that its DNA and RNA will come out and go straight to the nucleus. They will enter a molecule, which is like a factory, and make copies of the virus.
These new copies of the virus millions of copies will leave the already infected cell to infect other healthy cells, where they will multiply again. Infected cells can be damaged or die while hosting a virus.
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