I might not be ready to utter the word “cure,” but I might start letting it play around in my head occasionally while I keep my eye on these guys as they make their way through clinical trials.
Definition of VaccineMerriam-Webster’s Dictionary defines “vaccine” in the following way: a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease.
Indeed, that is what we think of when we consider vaccines – rolling up our sleeves (or dropping our pants) to get an injection that will prevent us from getting a number of terrible diseases, such as polio, diphtheria, measles, rubella…the list goes on (and continues to grow). Most people probably don’t think about what is in current vaccines, but just as the definition says, they contain viruses or bacteria that have been weakened or killed so that they don’t make us really sick, but do trick our immune system into mounting a response.
So What the Heck Is a MS Vaccine?
Therapeutic: Well, to explain MS vaccines, we have to stretch the definition of “vaccine” a little bit. First of all, all of the candidates that are referring to themselves as “MS vaccines” are not preventive in nature. No one is proposing, at this time at least, that children of a certain age will all get an MS vaccine in order to prevent them from ever developing MS in their lifetimes. Instead, the MS vaccine candidates are “therapeutic” vaccines, that is, vaccines that prevent or lessen the severity of symptoms or health problems from a disease that has already occurred.
Currently, the only approved therapeutic vaccine on the market is Zostavax, a vaccine to reduce the risk of shingles in older adults (the chickenpox, caused by the varicella zoster virus that also causes shingles, has already happened - the vaccine is supposed to keep it in check).
Organisms? This is another difference between traditional vaccines and the MS vaccine candidates. As mentioned, pretty much every traditional vaccine is designed to prevent an infectious disease – that is, a disease that is the result of becoming infected with foreign microorganisms, such as viruses or bacteria. However, MS is not an infectious disease. Although the disease process might get kicked off in some people by an infection, which “bug” is responsible is not agreed upon. Additionally, there must be other factors leading to susceptibility, or many more people would have MS.
Instead, MS is an autoimmune disease. For some reason, our own immune systems (are attacking the myelin that covers the nerves in our central nervous systems. In other words, MS is caused by something that our body is doing to itself, and not caused by a foreign invader. The MS vaccine candidates are designed to stop this from happening. Therefore, the components of the MS vaccine candidates are not microorganisms at all, but other things designed to “tweak” our immune systems in different ways to stop our immune cells from attacking our central nervous systems.
What are the MS Vaccines?There are currently four different MS vaccine candidates being tested: Tovaxin, NeuroVax, BHT-3009 and RTL1000. Each of these vaccines uses a different approach to reach its goal of stopping autoimmune activity against myelin.
Tovaxin: Tovaxin is an autologous T-cell vaccine, meaning that it consists of a person’s own myelin-reactive T-cells (the ones responsible for attacking the myelin in people with MS), which have been killed. By injecting a big dose of these back into the person, Tovaxin gets the immune system to destroy the rest of these cells in circulation – without affecting the rest of the immune system.
NeuroVax: NeuroVax is a T-cell receptor peptide vaccine, meaning that it is made from pieces of protein that resemble parts of the pathogenic T-cells that attack myelin. It is designed to stimulate the body to make more of the regulatory T-cells that control the activity of these pathogenic T-cells (people with MS have been shown to have lower levels of certain ones, called FOXP3+ regulatory T-cells).
BHT-3009: This vaccine is made of genetically engineered DNA that resembles the protein in myelin that our own immune cells attack, called myelin basic protein. DNA vaccines are being developed that also encode a "switch" that regulates the immune response, in effect, "reeducating" the myelin-reactive T-cells that are causing the problem.
RTL1000: “RTL” is short for “recombinant T-cell receptor ligands,” which are proteins that bind to the receptor of the T-cells that are damaging the myelin in people with MS. By tying up these receptors, the T-cells are no longer able to do damage. Some experts do not include this one in the “vaccine” categories, while others do.
See page two for more...