Vaccinations for some viruses (such as that causing tetanus)need boosters, every so often. Others don’t. I guess antibodies to some viruses are not permanent. But why? Why do some lsat a lifetime and others don’t?
I was always under the impression that it was due to changes in the strain of virus, not due to ‘loss’ of antibodies.
That’s true for certain viruses, such as the flu. However, it is not due to other viruses, such as tetanus.
Why would it be different for tetanus? Has it found some miraculous way to stop evolving?
If so, notify the creationists immediately!
barbitu8:
Tetanus is not caused by a virus, it is caused by bacteria. Further, the vaccine does not stimulate an immune defense against the bacteria, but against the toxin that the bacteria produce that causes the disease.
My guess is that if the toxin changed enough to avoid an immune response it may no longer be toxic.
In general, your body has ‘memory’ immunity cells coursing through the blood, waiting for measles or the flu or whatever. In the case of the flu, there are dozens if not hundreds of varieties of virus, and so it is nigh impossible to vaccinate against them all. This vaccine is one of the “the virus changes, so the vaccine must change” type.
In the case of something like measles, however, the virus does not evolve much, at least that part of it relevant to the vaccine does not evolve enough to make the vaccine ineffective, and if it did a new vaccine would have to be developed - simply reinoculating with old vaccine would not help.
The real story with booster shots is that your memory cells gradually die, just like other cells, so your immune response gradually fades. It never goes away entirely, just far enough away that a really nasty toxin/virus could get the upper hand on you. Some diseases such as pertussis are not dangerous in adults, so the vaccine is not boosted. Some diseases such as tetanus are dangerous in adults, so they are boosted.
It’s really much like exercising your muscles.
Finally, I remember reading recently that many vaccines that have been traditionally subject to boosters really don’t need to be boosted - that the immunity lasts much longer than previously thought. Does anyone else remember seeing this? I think it may have been in the ‘vaccination side effects’ thread in GD.
I knew tetanus is caused by bacteria, but thanks for informing me that you need a shot for the toxin. However, these “memory cells,” are they not the antibodies? And if they die off, like other cells, and are not replaced, unlike other cells, what about other diseases that are caused by viruses but for which booster shots are not needed: mumps, whooping cough, etc. Some may not be dangerous for adults, but mumps certainly is (are?) with complications not seen in children. And of course there is smallpox, which has been eradicated due to immunization of everybody. This, of course, is a separate case, since the virus has been eliminated, except in a few labs, as the only host for it was mankind. However, before it was eliminated, booster shots were never given. But, to repeat, aren’t these memory cells anitbodies? And it appears that memory cells for some die off fairly rapidly. Tetanus shots have to be repeated every 10 years.
Interesting thread. How do anti-venom vaccines work? These are usually made by injecting the venom 9be it snake, spider, or scorpion ) venom into a horse. The horse’s immune system will then produce ani-venom chemicals, which are then removed from the bllod, purified, and stored for future use.
Are the white blood cells active in fighting venoms?
Another question: why are evnoms so toxic? A black widow spider just needs enough to kill a fly, yet its venom is extremely toxic to humans.
Second things first. The black widow toxin, I think, is overrated as being extremely toxic to humans. A snake toxin, however, can be quite powerful, but a snake eats larger fauna.
The “anti-venom chemicals,” are types of white blood cells. I’m not an expert in this field, obviously (or I wouldn’t be posting the thread), but I do know that there are cellular and humeral “anti-toxins.” The cellular are those made to ward off an acute attack. While doing so, the body will also synthesize longer lasting cells, which will recognize the same toxins (by their protein coat) in the future. These are the antibodies. The immediate, cellular, defense consists of macrophages, which “eat” the toxins, and other variations of white blood cells that effect an immediate cure. The long-lasting cure resides in the antibodies, which consist of lymphocytes, made either in the bone marrow or the thymus (T-cells and B-cells). This is a very complicated process and I don’t know all the ramifications, but that’s it in a nutshell, as far as I know.
Wow. What timing. My immunology professor will be so proud of me.
No. Memory cells are cells. Antibodies are proteins. B cells, which include memory B cells, produce antibodies, which are released into the bloodstream. There are also memory T cells.
Don’t assume that just because you don’t need a booster, that you’re just as immune as you were just after getting the vaccine. A lot of this stuff has to do with the cost-effectiveness of administrating the vaccine. For instance, kids today don’t get the smallpox vaccine because it’s not around anymore. So the current generation is susceptible to smallpox, which makes it scary as a weapon. We could continue vaccinating, but the cost and difficulty of doing so is hard to justify when the risk is so small. Similarly with mumps. IIRC, the infective dose of mumps is much larger in adults than it is in children - you can get mumps as an adult, and it’s riskier if you do, but it’s also harder to get as an adult.
More generally, the differences in how different vaccines are administered has to do with how the body and the pathogen interact. Your body may need only a small priming or a large reminder to be effective against a given disease. It just depends. So it’s not that “memory cells for some die off fairly rapidly”, it’s just that you may need more of them to combat a given illness.
I’m going to attempt to answer several questions at once here. Let me know if I miss anything. Or if I confuse the hell outta ya.
When you give an antivenin to someone, you are giving them antibodies against the venom. Antibodies degrade relatively rapidly in the bloodstream. So these antibodies don’t last very long. But they don’t have to. They just need to block enough venom right at that moment to prevent the venom from screwing up your vital muscualar functions, like your beating heart or breathing.
A vaccine contains either part of a pathogen (Hep B vaccine), dead pathogen (rabies vaccine), or a weak version of a live pathogen (MMR vaccine). By putting this stuff in our body, our immune system will create its own antibodies and most importantly, its own memory cells. Memory cells stay with us for a long time and orchestrate the production of specific antibodies the next time we run into the pathogen again.
IIRC, you get a much longer lasting immune response when you use a live virus in a vaccine than a dead one. When a virus replicates in the body, a whole separate class of immune cells get involved that don’t get involved when the vaccine is a protein or inactivated virus.
The composition of the vaccine determines the efficiency of the immune response. This is why you need a booster for some vaccines and not for others. IIRC.
Also, after just having finished reading some in my Immunology textbook, you don’t always get a good immune response from the first injection, especially in children where some maternal antibodies may still be carrying some of the load. That’s why some vaccines are administered several times, to make sure at least one “takes”.
Yes, as I recall smallpox vaccine had to be given 3 times.
Something tht Douglips posted rivets my attention. The vaccine for tetanus is for the toxin, not the virus. There is no virus to be used for the vaccination. It appears, then, since a vaccine for a toxin, like tetanus, will be more short lived than a vaccine for a virus, esp. if a live virus is used, according to the later posting. That makes sense.
However, Douglips is wrong, I think, concerning hundreds of different flu viruses. There are hundreds of different cold viruses, and I think I’ve just about had them all, but there are not that many flu viruses. However, the flu virus does mutate rapidly, but not as rapidly asthe AIDS virus.
I remember not too long ago that it was said there were about 50 different cold viruses. Well, I’ve had more than 50 colds. How come I’m not immune from them all. Then the ante was upped, and they say there are actually hundreds of different cold viruses. Now, even if I’ve had them all, some of them apparently mutate. So I’ll never be safe from those dadburn colds.
I thought it was 5000 cold viruses
Every time I turn around the number goes up.
I may have been technically incorrect about the number of flu species (do they even use species for non-living entities such as viruses?), but ‘hundreds of different flu viruses’ is not far from ‘hundreds of different strains of flu viruses’ which has to be true if the virus mutates rapidly. If the virus you got last year is now extinct because it has mutated into a new flu virus, you have a fresh new challenge to your immune system, therefore last year’s virus and this year’s are distinct viruses.
The only way that a rapidly mutating flu virus could be reconciled with ‘not that many flu viruses’ is if there is a small set of mutations that the virus cycles through. Otherwise, the viruses are spreading out in strain-space, and every new strain is analogous to a new species. Evolution in action.
First, as to why you’re not immune to colds. Put simply, it’s because cold viruses don’t go through your blood. Put more complicatedly, because cold viruses invade epithelial mucosal membranes, you only get an IgA antibody response, which is not long lasting. (IgAs are the antibodies found in mucus - IgG and IgM are found in the blood) Typically, an IgA response only lasts for a month or so. So when people ask why we don’t have a cold vaccine, the answer is that we could make one, but you’d have to get injected with the 50 (or 500, or whatever - I don’t recall offhand how many cold viruses there are - in fact, I don’t think they’ve all been identified) vaccines every month. Personally, I think I’ll suffer a stuffed nose. Which, incidentally, is caused by the body’s inflammatory response caused by the detection of IgA bound to antigen.
Secondly, my previous post as to why some vaccines are repeated had a rather glaring omission in it. Making sure a vaccine “takes” is important, but more important is the issue of primary vs. secondary response. The first time you are exposed to an antigen, you get a primary response - mostly IgM antibodies, quite a long time before any are produced, and low levels of antibody in the blood. Thanks to the memory cells produced during the primary response, the next time you’re exposed, you get a secondary response, in which you get better antibodies (IgGs, which bind better and last longer), more of them, sooner, and for a longer time. Often, the second dose of vaccine is given to stimulate this stronger immune response to beef up the defenses. This is also why it’s a good idea to get vaccinated shortly before possible exposure - like just before leaving on a trip to developing countries.
Smeghead,
I don’t believe that is correct. IIRC, IgA is only produced in colostrum (clear serous fluid that is produced before breast milk). It’s function is unclear.
-LabRat
From Sherris Medical Microbiology, Third Edition, page 119:
Wee-hah! That’s the first time I’ve been called on something and had a textbook handy!
Actually, this book says nothing about which antibody type is in milk, and I think you’re right - that it is IgA. I’ll have to check another book when I get home. But whether or not it is also in milk, IgA is clearly the main antibody type in mucus.
My micro book says that IgA is secreted in a dimeric form at mucosal surfaces, so I think Smeg is right.
I think IgD is the mystery one.
There are just too many letters in immunology…
I think you’re right, Alpha. My book says that the “role [of IgD] is not fully understood,” and that it’s found in very low concentrations. Doesn’t say anything about it being in milk, though.