When a germ such as a virus or bacteria enters your body, your immune system goes into battle. It makes antibodies that locate the germ and launches an attack to fight it off.
After the antibodies have attacked they stick around in the body to protect you if the same germ enters your body again.
Often the antibodies can stop an infection by the remembered germ should it enter your body again. The infection is stopped before you even show signs of being sick!
What happens after you are injected with a viral vaccine? And which viral vaccine type is best?
(Note that I’m going to be talking about viral vaccines ONLY.)
First of all, there two basic types of viral vaccines: live attenuated vaccines (LAV) and inactivated (killed) vaccines.
LAV contain a vaccine virus that is a weakened version of the natural disease-causing virus. Inactivated vaccines use a killed version or a part(s) of the natural virus.
The body’s response to the vaccine virus in relation to the natural disease-causing virus has to do with the type of vaccine being administered, as well as how similar the vaccine virus is to the natural virus.
I’m going to go ahead and stop saying “vaccine virus”, and start calling this the “antigen”. An antigen is something foreign (in this case) that the body makes an immune response to, or something that’s the target for an immune response.
An inactivated vaccine contains all of the antigen needed to induce an immune response in the injected dose. Once it is injected into the muscle, the immune system begins to respond to this antigen. The LAV works a bit differently. There is only a very tiny amount of live weakened virus, and it must use the host body’s cells to reproduce in order to create the proper immune response. Once a LAV is injected into the muscle, the antigen migrates to the appropriate tissue in order to begin replication. The “appropriate tissue” in this case would be the tissue the natural virus would normally infect and replicate in.
Because the vaccine virus is so similar to the natural virus in LAV, these vaccines create an immune response virtually identical to the natural infection. The inactivated vaccine’s response is similar, yet one drawback is that immune stimulation occurs at the site of injection and not at the site of natural viral replication.
Some inactivated vaccines contain an adjuvant. An adjuvant is something added to the vaccine (most often an aluminum salt), and is used to help create a stronger immune response by activating the immune system or directing the antigen to the appropriate immune cells. If the vaccine has an adjuvant attached, the adjuvant dissociates and begins enhancing the “danger” signals already being picked up by the body’s first line of defense: the innate immune system.
The body’s immune system makes antibodies in response to something it believes needs to be destroyed. Most often, antibodies are made to attach to foreign substances, “immunogens”, such as bacteria, viruses, fungi, parasites, animal dander, cancer cells…and the list goes on. Occasionally antibodies are made to our own body’s tissues, as is the case with auto immune diseases.
Antibodies are made by the immune system and are basically just chains of proteins. Because they are formed in response to an immunogen and are made up of proteins–glycoproteins, rather–they are also called immunoglobulins in the scientific community.
Scientists use the short hand “IgY” when expressing immunoglobulins. The “Y” is replaced with a letter to signify the antibody class. The immunoglobulins can be divided into five different classes. These classes are based on the differences in the amino acid structure in specific regions of part of the antibody’s protein chains.
As stated in lesson 4, adaptive immune responses to foreign antigens are made up of cell-mediated and humoral processes. The lymphocytes that carry out these processes (T cells for cell-mediated and B-cells for humoral) have fundamental properties that are essential for proper immune system function.
And here they are:
If you haven’t been following my “beautiful immune system” lessons, I highly suggest you go back and read the first three lessons to catch up. These are short and simple lessons leading you through what will eventually be a great understanding of how the immune system works. I hope you enjoy! To the Beautiful Immune System Lessons.
Adaptive immunity (and innate immunity) can be separated further into two types of immunity: humoral immunity and cell-mediated immunity.