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.
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.
So far, so good.
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.
Stands for If I Recall Correctly.
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.
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!!
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.
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.
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.
Thanks to all who responded to my questions, esp. Alphagene and Smeghead. Both of you were great help. Got a free immunological lesson!
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.
(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.
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.
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.
I found this 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.
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.
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. 
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.