Why Not Antibodies Forever?

[barbitu8]

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?

[muppetsoup]

I was always under the impression that it was due to changes in the strain of virus, not due to 'loss' of antibodies.

[barbitu8]

That's true for certain viruses, such as the flu. However, it is not due to other viruses, such as tetanus.

[Timothy Campbell]

Why would it be different for tetanus? Has it found some miraculous way to stop evolving?

If so, notify the creationists immediately!

[douglips]

barbitu8:That's true for certain viruses, such as the flu. However, it is not due to other viruses, such as tetanus.

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.

Why would it be different for tetanus? Has it found some miraculous way to stop evolving?

If so, notify the creationists immediately!
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.

[barbitu8]

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.

[egkelly]

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.

[barbitu8]

Originally posted by egkelly
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.

[Smeghead]

Wow. What timing. My immunology professor will be so proud of me.

Originally posted by barbitu8
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?

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.


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.
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.

[Alphagene]

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.

[Smeghead]

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".

[barbitu8]

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.

[labdude]

I thought it was 5000 cold viruses

[barbitu8]

Every time I turn around the number goes up.

[douglips]

Originally posted by barbitu8
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 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.

[Smeghead]

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.

[LabRat]

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

[Smeghead]

Originally posted by LabRat
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:

Immunoglobulin A has a special role as a major determinant of so-called local immunity in protecting epithelial surfaces from colonization and infection. Certain B cells in lymphoid tissue adjacent to or draining surface epithelia of the intestines, respitory tract, and genitourinary tract are encoded for specific IgA production.
...
The major role of sIgA (the "s" stands for secretory - Smeghead) is to prevent attachment of antigen-carrying particles to receptors on mucous membrane epithelia.


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.

[Alphagene]

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...

[Smeghead]

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.

[Smeghead]

I'm home now, and according to my Immunology textbook, IgA is the primary type of antibody in mother's milk (in humans, anyway), though IgM is also present. IgG, however, is the main type transferred through the placenta.

There. You can all sleep tonight now.

[barbitu8]

Let's see if I have this straight. There are 5 different antibodies aka immunoglobulins (IgA, D, E, G, & M)made by a B-lymphocyte, which production is regulated by a helper T-lymphocyte. IgE is the culprit in allergies. The antibodies are assisted by macrophages, which ingest foreign substanes and present them to the T cells, so they can prompt the B cells to act.

Now, I have several more questions. First, what the heck is this IIRC I see in a lot of posts? Obviously an abbrev. for something. Second, are there any vaccines against bacteria (not the toxin)? And if not, why not? I understand that antibiotics can eliminate bacteria, and it may not be cost effective to make vaccines for them. However, with many bacteria becoming resistant to a whole spectrum of antibiotics, would vaccines be a viable option? Third, why can't a cell's intracellular mechanisms rid the body of those viruses that inhabit a cell but don't prompt the cell to expose the antigen to the blood? I'm thinking specifically of HIV, which inhabits the T cells, and the herpes viruses which inhabit ganglia. The antibodies can't get rid of them as long as they remain in the cell, but a cell has its own way of eliminating unwanted proteins (degradation, etc).

A statement was made in a previous post that memory cells die like all other cells. Is that sos? Neurons die eventually, but not until we reach a ripe old age.

[Smeghead]

Originally posted by barbitu8
Let's see if I have this straight. There are 5 different antibodies aka immunoglobulins (IgA, D, E, G, & M)made by a B-lymphocyte, which production is regulated by a helper T-lymphocyte. IgE is the culprit in allergies.

So far, so good.


The antibodies are assisted by macrophages, which ingest foreign substanes and present them to the T cells, so they can prompt the B cells to act.

There's helping in both directions. Antibodies bind to antigens, which makes phagocytosis by macrophages easier. These macrophages (and other antigen-presenting cells) then present the antigen to the helper T cells. Kind of a feedback mechanism.


Now, I have several more questions. First, what the heck is this IIRC I see in a lot of posts? Obviously an abbrev. for something.

Stands for If I Recall Correctly.


Second, are there any vaccines against bacteria (not the toxin)? And if not, why not? I understand that antibiotics can eliminate bacteria, and it may not be cost effective to make vaccines for them. However, with many bacteria becoming resistant to a whole spectrum of antibiotics, would vaccines be a viable option?

I'm not eniterly sure. See, you can't have a vaccine against a bacterium as a whole, because the immune system doesn't see the whole bacterium. It recognizes bacterial proteins, often ones that are expressed on the surface.
Getting closer WAG territory, bacterial vaccines would suffer from the same problems as antibiotics - mutations in bacterial proteins would tend to render both of them ineffective.


Third, why can't a cell's intracellular mechanisms rid the body of those viruses that inhabit a cell but don't prompt the cell to expose the antigen to the blood? I'm thinking specifically of HIV, which inhabits the T cells, and the herpes viruses which inhabit ganglia. The antibodies can't get rid of them as long as they remain in the cell, but a cell has its own way of eliminating unwanted proteins (degradation, etc).

At least in the case of HIV, it's because while the virus is dormant, it's not making any protein for the cell to express. It exists entirely as a stretch of DNA incorporated into the host genome somewhere. There's nothing for the immune system to see. I'm a little fuzzy on how herpes is dormant, but I think it's similar.
Incidentally, it may seem like a good idea for a virus to interfere with the cells' production of MHC proteins, which are the ones that do the antigen presenting - if the MHC is gone, no antigen can be expressed, so the cell is safe. But, our Natural Killer cells (yet another cell type) attack and destroy any cell that doesn't express MHCs. Take that, virus!!


A statement was made in a previous post that memory cells die like all other cells. Is that sos? Neurons die eventually, but not until we reach a ripe old age.
Yes. They do die. There's evidence that they reproduce before they do, though. Of course, I think the previous post you mentioned was made by me, so you may still want independent confirmation.

[Alphagene]

Originally posted by barbitu8
Second, are there any vaccines against bacteria (not the toxin)?
Yes, killed whole cell preparations of B. pertussis used to be provided in the DPT vaccine. Now they use acellular preparations.

Other killed preparations of whole bacteria are present in vaccines for typhoid fever (S. typhi), typhus (R. prowzekii), and plague (Y. pestis).

Some vaccines containe live bacteria too. In Europe, children are vaccinated against tuberculosis using the BCG vaccine. It contains live attenuated M. bovis. It is not given to the general population in the US, but despite that, it is the most widely administered vaccine in the world. Additionally, cholera vaccines contain both live V. cholerae and killed cells.

In case you're wondering, most people aren't vaccinated for all these diseases. Many of the above vaccines are only given to military personnel or microbiologists.

Originally posted by barbitu8
Third, why can't a cell's intracellular mechanisms rid the body of those viruses that inhabit a cell but don't prompt the cell to expose the antigen to the blood? I'm thinking specifically of HIV, which inhabits the T cells, and the herpes viruses which inhabit ganglia. The antibodies can't get rid of them as long as they remain in the cell, but a cell has its own way of eliminating unwanted proteins (degradation, etc).)?
Good question. In addition to sneaking its genome into the host's DNA like Smeg explained, many viruses have various tricks. Remember, viruses need a living cell to reproduce. Ideally, when a cell is infected, it will signal the immune system and wait to be killed. Many viruses have ways of blocking this signal. Alternatively, some cells will attempt to kill themselves when infected. This is known as apoptosis. Many viruses, including herpes, produce proteins that prevent this from occurring.

[barbitu8]

Thanks to all who responded to my questions, esp. Alphagene and Smeghead. Both of you were great help. Got a free immunological lesson!

[barbitu8]

I want to add this postscript, esp. addressed to Alphagene and Smeghead. Did you read the paper today? It seems that they now have a vaccine for staph infections, caused by a bacterium. The article implied that a vaccine is necessary because the bacterium is becoming immune to the antibiotics. One of you guys, I don't remember which, said that a vaccine won't help, because the bacterium will become immune to the vaccine too.

What's confusing in these lay articles in the press is the terminology used. The article says, "The vaccine triggers the body to make fresh antibodies against staph. After one year, the patients' antibody levels dropped and their protection against staph began to fade." Now I would think that that would be immaterial so long as the memory cells induced by the vaccine did not die.

[Smeghead]

(a) Do you have a link or source? I'd like to read this.
(b) Generally speaking, don't rely on the news to give scientifically accurate descriptions of what's going on.

[barbitu8]

It was in yesterday's Charleston Post & Courier. Try:
http://www.charleston.net I don't know how to link you directly, and that doesn't seem to be a click-on link. You can, however, access that website, and make a connection to the Post & Courier for yesterday's news.

I don't rely on the newspapers for accuracy, but generally they're in the ballpark.

[barbitu8]

Smeghead, the cite I gave does not give an "archive" for yesterday's paper. I tried http://www.nytimes.com and searched for vaccine for staph, but there were none. I don't hae the paper any more, but a friend of mine says he has it, and if you can't find the article anywhere, I'll type it out in full, but I won't see my friend again until Monday.

[Smeghead]

I found this (http://www.usatoday.com/life/health/general/lhgen085.htm) article which seems to mention something similar to your story. Here's everything I can think of that might be relevant, but take it all with a grain of salt because I could easily be wrong:

After starting this sentence half a dozen times, I've decided to go with an analogy: think of a bacteria like a car. OK. Antibiotics tend to have specific targets in the cell - they may gum up the radiator, or let the air out of the tires, or whatever. The point is that each drug has its own specific target. That means that to get around it, the bacteria just has to make one change - protect the air valve on the tires, change the design of the radiator, whatever. All right, you probably knew that already.

Now, vaccines. I know that there have previously been vaccines against bacterial toxins - proteins secreted by the bacteria that do the actual damage - and these have been pretty effective, because if the shape of the toxin changes to get around the immune system, the changed shape probably will prevent it from doing any damage, too. If they've come up with a vaccine against an entire bacteria, which is what I'm assuming happened here, that will be very useful. Going back to the car analogy, the immune system will be able to recognize the shape of the headlights, the door handles, the trunk lid, the hubcap shape, and with the help of antigen-presenting cells, the shape of every piece of the engine and even the seat covers. Obviously, this will make it harder for the bacteria to avoid through mutation - it'd have to change so much it wouldn't really even be the same bacteria anymore. Finally getting to your original question, yes, the bacteria could mutate around this type of vaccine eventually, but it would be harder than simply developing antibiotic resistance, which again would only require one target change.

Now, a major caveat - as I was typing this, I realized that more likely, they've developed a vaccine based on one bacterial protein, rather than the whole-cell thing I just overexplained. If this is the case, then they picked one protein, like say the hood ornament, and made a vaccine out of that. In this case, we're back to the one target thing again, so resistance is possible. However, there is reason to hope that the vaccine will be useful longer than the drugs. You can target for more proteins with vaccines than with drugs. A vaccine-sensitive protein merely has to be on the cell, while a drug-sensitive protein actually has to do something important. If the researchers were smart, they would pick a highly conserved protein - one that changes very very slowly or not at all. Typically, these are proteins that are vital to the cells' survival and that can't be changed without killing it. Also, when you use a vaccine, you get the body's immune system working for you, instead of shooting in the poison and hoping it gets them all. The immune system is extremely sophisticated and good at what it does.

Oh, and finally, as to why the immune response faded - I dunno. I could think of a few possible reasons, but I'd have to know more before hazarding a guess. I'd really like to see the original paper on this thing to see what it is and how it works.

Sorry again about the length of this. I realize I made it sound kind of dumbed-down, but that's really more for me. I understand it myself much better when I use layman's terms. Anyway, I don't really have an answer, but that's at least some stuff to think about.

[barbitu8]

Thanks Smeghead. I've found the article and it is based on the same as the USA had, but goes into more details. I'll quote the article:

A vaccine has been shown for the first time to protect against life-threatening staph infections, a major hazard among hospital patients, researchers said Tuesday.

The genetically engineered vaccine was tested in kidney dialysis patients, and cut their risk of staph blood poisoning in half for nearly a year.

"I am quite encouraged by this. It could be a major breakthrough in this area," said Dr. Steve Black of the Kaiser Permanente Vaccine Study Center in Oakland, CA.

Black presented the results at the annual infectious disease meeting of the American Society for Microbiology. The vaccine, called StaphVAX, was created at the NIH and is being developed by Nabi Corp. of Boca Raton, FL, which financed the latest study.

Staphylococcus aureus is a common and oordinarily harmless inhabitant of the human nasal tract. It can live for days outside the body on almost any surface and spreads widely in hospitals, where it can cause serious infections among those who are already sick, especially if they have weak immune defense.

Staph can be deadly if it invades the bloodstream. It can lead to pneumonia, encephalitis, liver abscesses and olther problems. Staph infections are relatively common among people who use needles frequently, such as diabetics and dialysis patients, elderly people in nursing homes and those who are hospitalized for surgery and a variety of other conditions.

Doctors conducted the first large test of StaphVAX in dialysis patients because typically between 1% and 3% of them get bloodstream staph infections each year. Robert B. Naso, Nabi's research director, said the company will seek approval soon from the FDA to produce and sell the vaccine.

The study enrolled 1804 patients at 90 dialysis centers in CA. Half got the vaccine, while the rest took dummy shots. The vaccine appeared to quickly lower the risk of staph. After 10 months, there wre 11 serious infectitons among those getting the vaccine, compared with 26 in the unprotected group, a 57% reduction.

The vaccine triggers the body to make fresh antibodies against staph. After one year, the patients' antibody levels dropped, and their protection against staph began to fade.

Staph infections are of particular concern because the bacteria is growing immune to the antibiotics commonly used to treat it. Half of all staph that circulates in hospitals is resistant to methicillin, the standard drug. Now it is developing resistance to vancomycin, the main backup drug.

Black said researchers will also probably explore the possibility of giving booster doses to people who must keep up resistance for along time, such as those on dialysis.

That's it, Smeghead, the whole quote. I used abbrev.,ut otherwise I typed it verbatim. You note they talk about the antibodies dropping, but did not mention the memory cells. Of course, this is from a daily newspaper. This may be covered in more technical periodicals in the near future. I get Science News, and it may be covered there, and I'm sure you get even more technical journals, tho I don't know what you do or if you're a graduate student, or what.

I only use the office computer, and I'll be off tomorrow, but I sometimes check the computer in the evenings. I plan to get my own computer soon, as now I find so much use for it, with this feature and all the expertise out there in the TM, plus the fact that I can't play chess games on this computer as it has a firewall.

[Smeghead]

Hmmm. Interesting, though it didn't mention exactly what the vaccine is made of. Since it called it "genetically engineered," I suspect it's just one protein - you take the gene for the protein of interest, insert it into another bacterial strain, grow it up, harvest the protein, and inject the purified protein as the vaccine. That would make the most sense.

As for why immunity decreased after a year, well, shoot. I can't think of anything offhand that would disappear after nearly a year. You're right, memory cells should last longer than that. It may just be a trial and error thing. Different vaccines produce different levels of immune response - things don't always work exactly as they should. Maybe with some more fiddling they'll be able to get better results. I dunno.

BTW, thanks for the complement, but I'm still a measly little undergrad. You have renewed my hope that one day I may perhaps be more. Coincidentally, in my lab class today I proved that I had isolated Staph aureus from my own skin. Better stop licking myself, I guess. :D

[barbitu8]

OK, what does BTW stand for?

A lot of coincidences around. Coincidentally I asked about a bacteria vaccine, and pronto - I read about one. I'll let you know if I find out more specifics, from Science News, or whatever.