modern medicine has allowed us to really manipulate our technology to mount better defenses against pathogens. We basically have found ways to manipulate our own immune systems to save us the trouble of getting sick. We call this immunization, which is basically when an organism's immune system gains. The specific defense against some pathogen is usually happens through what's called vaccination. Vaccination is going to be the introduction of a vaccine to prime the immune system. Thio deal with later infections. Basically, it allows you to mount a primary immune response. Thio some weekend or killed form of pathogen. That's not actually going to get you sick so that if you ever in the wild, so to speak, encounter you know that nasty bug in its, uh, form where it can actually get you sick, you have a secondary immune response ready to go to beat it down. A vaccine is a biological preparation that contains antigens, and, as I said, usually it's like a weakened or killed form of a pathogen. The name comes from the Latin word for cow, which is vodka and essentially, uh, if you're wondering why this has anything to do with cows, it's because the first, uh, you know, a famous case of vaccination in Western medicine anyways, was with this guy right here. His name is Edward Jenner, and he used the, uh, cowpox virus to vaccinate people against smallpox, which was a rampant and deadly disease. It was pretty gnarly how he did it. I mean, he literally took basically a two pronged needle that looked like that and dipped it in a vial of cowpox so that a liquid droplet would kind of stick between the two prongs, and then he would just prick you with it. And, you know, make sure that some of that liquid gets into your blood Pretty gnarly stuff. But it worked. And this would actually be an example of a type of vaccine that contained what's called an attenuated virus. Basically, uh, it's an infectious virus that's cult cultured in a species other than a host, so it won't infect the host cells. This is not exactly an intent attenuated virus because, you know, cowpox is its eyes, its own disease, but it's highly related to smallpox. It's just that it infects cows instead of humans. So very similar idea to an attenuated virus. You can also see vaccines that air called sub unit vaccines that contain isolated viral proteins. So, basically, you know, some scientists will, uh, take a virus and break it down and find some good antigens to use and then, uh, inject you with that so that you can recognize the antigens, but you never actually have to have the virus inside you. You can also get an inactivated virus, which will be like a damaged virus that contains antigens but can't cause infection now, often in, uh, you know, biotechnology, you'll see things called monoclonal antibodies used. And these air just antibodies that air prepared from a single clone of B cells. Uh, you know, specific for some epic tope. And you know, these will be used often in in research for many, many different purposes. But you probably will see that name come up now. You know what it iss now? Things could go wrong with the immune system. Allergies are common example of an abnormal immune response. Thio Ananta gin, which will call an allergen. Basically, it's not something that's actually going to get you sick, but your body still mounts an immune response to it. You know, That's why, for example, if you're allergic to cats or something, you know, uh, the cat dander will make you, um, sneezy. You can get that inflammatory response right. You'll get all swollen and puffy. Um, it's just your immune system going a little overboard, right? Identifying something is a threat that's not actually a threat now allergies. Air unpleasant, but they're not nearly as dangerous as auto immunity, which is when a new immune response is directed at self molecules and the cells of the organism. Essentially the cells of your immune system attack and kill your own body, for example, and diabetes mellitus it, you know, can be caused by an auto immune reaction that has the immune system specifically target the cells that and target and kill the cells that produce insulin. And that's why people with that, uh, condition can't produce insulin even though they have a pancreas because their immune system, you know, went haywire and just killed those insulin producing cells in the pancreas. Now, HIV or human immunodeficiency virus is a very heavily researched virus that infects and kills CD four plus T cells and macrophages. And this is, uh, you know, obviously very dangerous because it's a virus that actually targets and attacks the adaptive immune system, which is really bad news because it it essentially, can prevent your immune system from being able to mount a new immune response not only against it, but other pathogens as well. Uh, you know, those helper T cells, which are the CD four plus T cells are needed for both the hue moral response and the cell mediated response. Remember, they're gonna help activate site a toxic T cells, and they're gonna help activate B cells to produce antibodies. So basically, this virus attacks. You know, the most one of the most vulnerable cells of the immune system. If you want to just take the whole system out now, there's a condition that develops from HIV that we know as AIDS or acquired immune deficiency syndrome. Basically, this is a It's not a separate disease. It's, ah, severe weakening of the immune system from an HIV infection. If you have an HIV infection, uh, for a long time or it's untreated for a while or something, it can lead to your immune system getting so weak that you can't fight off any infections any little thing can get you sick to the point where it can kill you. And that is, you know, sort of how HIV isa lethal diseases. It just takes out your immune system so that, even like a little cold or something, uh, could could be fatal. And here, uh, not to end on to darken out. But here you can see, uh, a cell being attacked by HIV virus. So with that, it's all I have for this lesson. Stay healthy, guys. But if you get sick now, you know what your body is doing to fight against it.