Captions are on! Click CC at bottom right to turn off. Antibiotics. Antivirals. Vaccines. Have you ever wondered what they do or how
they work? One thing to understand is that they can greatly
help the work of your immune system. Your immune system is fascinating. We’re being very general here because this
is not a video about the immune system specifically, but it’s important to understand a few basics
of the immune system to comprehend the amazing work of antibiotics, antivirals, and vaccines. Your immune system is designed to protect
you against pathogens. Pathogens can be all kinds of things. Certain kinds of bacteria. Viruses. Infectious protists, yes, unfortunately there
are some dangerous types of protists. Certain types of fungi. Parasitic worms. These can all be pathogens. Your skin is actually part of your first line
of defense in protecting invasion of pathogens. Not just as a barrier, but also, there are
helpful microbes that colonize your skin and can keep bad microbe numbers down. Mucous membranes are also part of the first
line of defense. But pathogens do get in, and when they do,
you have more lines of defense to protect you. For example, your second line of defense includes
non-specific white blood cells such as macrophages. These cells are incredible; they actually
engulf pathogens. These are involved in a fascinating response
called the inflammatory response which we could have an entire video on. Then, you have a third line of defense. Unlike the first two lines of defense, the
third line of defense is considered more of a specific defense as it can target specific
pathogens. Examples of immune cells involved in this
specific response include white blood cells known as lymphocytes. T lymphocytes, or T cells, and B lymphocytes,
or B cells. B and T cells are very specific for reacting
to antigens. Antigens are molecules that can be found on
the pathogens. Although we should point out that antigens
can be anything foreign in your body ---for example, someone who has an allergy to pollen
may react to pollen antigens. An antigen can activate a response from a
T cell and/or a B cell. And, while again, this video doesn’t get
into the fascinating types of immune responses with these cells which we encourage you to
explore, we do want to mention one very important fact before we move on. There are memory B and T cells. This is very significant because these cells
can “remember” a pathogen. These memory B and T cells remain in the body. If the pathogen returns, these cells can multiply
and combat the pathogen quickly and effectively. We’ll explain why that’s especially important
when we get to vaccines. So back to antibiotics, antivirals, and vaccines. How are they involved with all of this…what
do they do…how do they work? Let’s start with antibiotics. Antibiotics target one type of pathogen: bacteria. Now while not all bacteria are bad---in fact,
many bacteria play many helpful roles in both our bodies and the environment---the infectious
types of bacteria can be a problem. It is bacteria that cause strep throat, staph
infections, some types of pneumonia, UTIs. And while your immune system will go after
these bacteria, sometimes it could use a little help. That’s where antibiotics come in. Antibiotics can destroy bacteria in many ways…they
can damage bacterial cell walls or block the production of critical proteins the bacteria
may need. Antibiotics can be prescribed by a doctor
in a pill form, but they can also be injected or delivered in an IV. Now the word antibiotic can be taken apart
where you see “anti” which can mean against and “bio” which can mean life. And that’s really helpful because you don’t
want to get it mixed up with two other words that, unfortunately, sound quite similar. One of those words is antigen, as we had mentioned
earlier, which is a molecule that can be found on a pathogen. Antibodies are proteins made by some of your
immune cells, such as B cells, that can be used to help fight pathogens. They often have this fascinating Y like shape. Some antibodies bind to a pathogen making
the pathogen unable to function correctly. But antibodies also can be used to mark pathogens
so they can get “eaten” by a macrophage. Now, we had mentioned that immune cells can
contain a type of memory when they encounter a pathogen. This can include the ability to produce antibodies
against pathogens that your immune cells have already encountered. And this is where vaccines come in. Vaccines are a way of exposing your body to
an inactive form of a pathogen or a weakened form of a pathogen---since it’s inactive
or weakened, it prevents you from actually developing the disease from the vaccination
itself. However, your body still launches an immune
response. By launching an immune response, which includes
the production of antibodies against the pathogen, the immune system will retain “memory”
against the pathogen. That way if your body ever encounters the
real, active pathogen---your body will be familiar with it already and therefore we
say that your body already has immunity against the pathogen. This can result in allowing your body to launch
an attack against the real thing more quickly and efficiently. Vaccines can be effective against many different
types of bacteria and viruses. We take for granted the amazing work of vaccines
in keeping people from developing devastating bacterial and viral diseases. But thanks to vaccines, some horrible bacterial
and viral diseases are considered eradicated in some areas, but it is important for them
to be continued to prevent some of these diseases from re-emerging. There’s also another really important thing
you should know about vaccines. Some people may not be able to receive certain
vaccinations---from someone whose immune system is severely compromised because they perhaps
have an illness of some type---to a newborn baby not yet old enough to receive many vaccines---to
a pregnant mother. These vulnerable populations rely on something
known as “herd immunity” - that is, if others around them are vaccinated against
a certain pathogen, that may offer them a degree of protection against that pathogen
because it cannot easily spread to them. So vaccinations not only offer protection
for the person receiving them, but also, they can offer protection for others around them. For an example of this, let’s consider the
contagious viral disease Rubella. A vaccine for Rubella is given typically in
early childhood. Rubella generally results in a rash with some
mild symptoms such as a low grade fever or sore throat. But, if a pregnant woman contracts this virus,
her unborn child can suffer severe birth defects. But women who are pregnant are advised not
to get the Rubella vaccine while they’re pregnant so they can be considered a vulnerable population
during that timeframe if they do not already have immunity from this virus. Herd immunity can be protective in an example
such as this. Learn more about “herd immunity” in some
of our further reading suggestions. And, because there is a lot of misinformation
about vaccines out there especially as of recent years, we have also included some further
reading suggestions about vaccines in general that you may want to check out. So as we discussed, vaccines can help our
immune system be ready for all kinds of pathogens, including bacteria and viruses. Recall that antibiotics are specific against
bacteria only. But antivirals are designed to help target
viruses. Antivirals can come in many forms such as
a pill, liquid, or given as an IV form. They can make a virus infection less severe,
although many of them have to be given in a specific time frame after contracting the
virus in order to be effective. Many antivirals work by affecting virus replication,
which is difficult, because if you recall from our virus video, viruses reproduce by
using your own cell’s machinery. So an antiviral needs to be able to stop the
virus without negatively affecting your own cells. For example, if the virus has a critical protein
that it uses the host cell to make---an antiviral can be designed to stop that protein from
being made---but it would be important to verify that the protein is not one that is
used by your own cells. One last thing. Pathogens can change. Mutate. Evolve. In our natural selection video, we talk about
how antibiotics may not be as effective against certain types of bacteria due to antibiotic
resistance that can occur. In our virus video, we mention how viruses
can mutate. An example is the virus that causes influenza,
aka the flu. That virus changes frequently so a flu shot
vaccine that works this year likely won’t be as effective against the influenza virus
that is the most common next year. There are actually scientists that work hard
to predict which influenza virus type will be the most common each year, and the flu
vaccine is designed to launch an immune response against that specific type so that, if you
encounter it, you can have protection. That’s why there is a different flu shot
each year and sometimes the effectiveness can vary each year. With mutations occurring, this is also a challenge
in developing antivirals. An antiviral that was designed to target a
specific virus may not work on a mutated form. Scientists continue to look for solutions
to counter the ever-changing pathogen world. Well that’s it for the Amoeba Sisters, and
we remind you to stay curious.
