Immunology questions

[MoosePilot]

I'm taking a correspondance course on immunology and I regret not having study partners. If anyone knows anything about immunology, is currently taking a similar course, or would just like to comment on some questions, feel free to chime in. Even if you're wrong, I like bouncing ideas around.

Two questions I'm working on:

5. Explain why the following statements are false.

5.a. The amino acid sequence of a protein can be determined from the
nucleotide sequence of a genomic clone encoding the protein.

I think this is a fairly straightforward question asking about transcription and translation. I think the answer is because you couldn't know whether you were dealing with the sense or anti-sense strand and both would still have included, which wouldn't lead to the correct amino acid sequence. Anyone else have thoughts?

6. Why wouldn't you use serum from someone with immunity to a bacterial
infection to protect another from the same type of infection?

This one has just stumped me for now. I think I'm tired and the answer might be so simple I'm overlooking it.

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[dizzydog]

I'm taking a correspondance course on immunology and I regret not having study partners. If anyone knows anything about immunology, is currently taking a similar course, or would just like to comment on some questions, feel free to chime in. Even if you're wrong, I like bouncing ideas around.

Two questions I'm working on:

5. Explain why the following statements are false.

5.a. The amino acid sequence of a protein can be determined from the
nucleotide sequence of a genomic clone encoding the protein.

I think this is a fairly straightforward question asking about transcription and translation. I think the answer is because you couldn't know whether you were dealing with the sense or anti-sense strand and both would still have included, which wouldn't lead to the correct amino acid sequence. Anyone else have thoughts?

6. Why wouldn't you use serum from someone with immunity to a bacterial
infection to protect another from the same type of infection?

This one has just stumped me for now. I think I'm tired and the answer might be so simple I'm overlooking it.

5a. maybe also because you don't know what part of the genome is processed and coded for....ie, the nucleotide sequence alone won't tell you whether you have an intron or exon portion of the sequence...if you knew the exon portion then you could figure out the codons and amino acid sequence. Does that make sense?

 

[MoosePilot]

5a. maybe also because you don't know what part of the genome is processed and coded for....ie, the nucleotide sequence alone won't tell you whether you have an intron or exon portion of the sequence...if you knew the exon portion then you could figure out the codons and amino acid sequence. Does that make sense?

Yes, it does. That's along the lines I was thinking.

 

[PhillyEaglesFan]

For 5a, another possibility is splicing--if I'm reading the question correctly (which I may not be ). That would make a discrepancy b/t the nucleotide and aa sequence.

EDIT: man, ya'll are some fast mofos.

 

[xanthines]

Eukaryotic systems have introns which would be included in GENOMIC sequences. You'd have to use the cDNA (c = complementary) sequence to determine amino acid sequences. You can cDNA by reverse transcribing mRNA which has undergone the splicing/processing to get rid of those pesky introns. Your sense/antisense explanation seems to make sense (pun intended), but there are specific codons for starts and stops, which should occur at the beginnings and ends of cDNA sequences. Antisense sequences would either be missing the start codon or contain many many stops throughout the sequence.

I don't know the answer to number 6. Sorry!

-X

5. Explain why the following statements are false.

5.a. The amino acid sequence of a protein can be determined from the
nucleotide sequence of a genomic clone encoding the protein.

I think this is a fairly straightforward question asking about transcription and translation. I think the answer is because you couldn't know whether you were dealing with the sense or anti-sense strand and both would still have included, which wouldn't lead to the correct amino acid sequence. Anyone else have thoughts?

 

[mercaptovizadeh]

I'm taking a correspondance course on immunology and I regret not having study partners. If anyone knows anything about immunology, is currently taking a similar course, or would just like to comment on some questions, feel free to chime in. Even if you're wrong, I like bouncing ideas around.

Two questions I'm working on:

5. Explain why the following statements are false.

5.a. The amino acid sequence of a protein can be determined from the
nucleotide sequence of a genomic clone encoding the protein.

I think this is a fairly straightforward question asking about transcription and translation. I think the answer is because you couldn't know whether you were dealing with the sense or anti-sense strand and both would still have included, which wouldn't lead to the correct amino acid sequence. Anyone else have thoughts?

6. Why wouldn't you use serum from someone with immunity to a bacterial
infection to protect another from the same type of infection?

This one has just stumped me for now. I think I'm tired and the answer might be so simple I'm overlooking it.

1.) Post-transcriptional processing, i.e. splicing, introns, exons, etc.

2.) Because the immune system of the recipient could raise antibodies against the (foreign) proteins of the donated serum, including antibodies against the donated antibodies!

 

[PhillyEaglesFan]

1.) Post-transcriptional processing, i.e. splicing, introns, exons, etc.

2.) Because the immune system of the recipient could raise antibodies against the (foreign) proteins of the donated serum, including antibodies against the donated antibodies!

Guess we have a winner.

 

[DrThom]

1.) Post-transcriptional processing, i.e. splicing, introns, exons, etc.

2.) Because the immune system of the recipient could raise antibodies against the (foreign) proteins of the donated serum, including antibodies against the donated antibodies!

I'm not sure #2 is right.

The immune system does this anyway since every new antibody it make is considered foreign due to hypervariability (self or not). [see anti gp120 antibodies]

It might have something to do with tolerance of self antigens but don't take my word for it, I got a B in Immuno.

 

[Phil Anthropist]

6. Why wouldn't you use serum from someone with immunity to a bacterial
infection to protect another from the same type of infection?

2.) Because the immune system of the recipient could raise antibodies against the (foreign) proteins of the donated serum, including antibodies against the donated antibodies!

Whaddup Moose?!

My understanding of immuno isn't what it used to be, but my guess is that won't develop acquired/adaptive immunologic memory (specificity and resistance). Even if you had antibodies for the antigens (the bacteria) injected into you, it would not protect you from future infections (insults). That is, even if you somehow are able to get temporary protection, you won't develop active acquired immunity to prevent future insults.

It is possible to get immunoglobulin (antibodies/proteins) injections (a form of artificial, passive immunity), which by definition are exogenous. This is often used in anti-venoms. Passive immunity can also be given naturally. We see this when maternal antibodies are transferred to the fetus via the placenta and also to newborns via breast milk. These are antibodies developed exogenously and an immune response is not made against them. So I don't think the reason why is that the immune system of the recipient could raise antibodies against the foreign proteins of the donated serum.

When you get infected by an antigen either artificially (e.g., weakened/attenuated antigen) or naturally (e.g., catching the chicken pox), your immune system has the ability to develop immunlogical memory. This is why when you get something like chicken pox (I know, bad example because it's not bacteria), it's nearly impossible to get it again.

So I guess my answer is you won't get long-term protection from the antigen. But again, it's been awhile since I've had immuno and I could be wrong.

For No. 1, you're not gonna get anything out of me other than neural flatulence

 

[MoosePilot]

Whaddup Moose?!

My understanding of immuno isn't what it used to be, but my guess is that won't develop acquired/adaptive immunologic memory (specificity and resistance). Even if you had antibodies for the antigens (the bacteria) injected into you, it would not protect you from future infections (insults). That is, even if you somehow are able to get temporary protection, you won't develop active acquired immunity to prevent future insults.

It is possible to get immunoglobulin (antibodies/proteins) injections (a form of artificial, passive immunity), which by definition are exogenous. This is often used in anti-venoms. Passive immunity can also be given naturally. We see this when maternal antibodies are transferred to the fetus via the placenta and also to newborns via breast milk. These are antibodies developed exogenously and an immune response is not made against them. So I don't think the reason why is that the immune system of the recipient could raise antibodies against the foreign proteins of the donated serum.

When you get infected by an antigen either artificially (e.g., weakened/attenuated antigen) or naturally (e.g., catching the chicken pox), your immune system has the ability to develop immunlogical memory. This is why when you get something like chicken pox (I know, bad example because it's not bacteria), it's nearly impossible to get it again.

So I guess my answer is you won't get long-term protection from the antigen. But again, it's been awhile since I've had immuno and I could be wrong.

For No. 1, you're not gonna get anything out of me other than neural flatulence

Ok, so the problem may be mostly that getting a little bit of freebie antibodies is just so little help that it's not worth it? You need to introduce killed/attenuated pathogen to prompt the body to adapt it's own immune response? I like it, anyone else?

No neural flatulence!

 

[DrYo12]

I think for #6 it has to do with MHC. Let's say you have two people that are not histocompatible. You may end up creating a whole new immune response against the foreign serum. Likewise, bacterial infections are best fought via B cell activation, and anitbodies created by your plasma cells.

 

[DrThom]

If it is whole serum as well, there are a host of antibodies present that could act against the recipients antigens. Why do we like to transfuse with type-specific blood? Because it will not react with the antibodies in recipient serum. Likewise, there could be antibodies (for any of the countless numbers of different blood types or etc.) in the donor serum that could react with the recipient.

This is probably not the answer but certainly a possibility.

 

[DrThom]

I think for #6 it has to do with MHC. Let's say you have two people that are not histocompatible. You may end up creating a whole new immune response against the foreign serum. Likewise, bacterial infections are best fought via B cell activation, and anitbodies created by your plasma cells.

I could be wrong but if you are just transfusing with serum, you shouldn't have to worry about MHC because you are not transfusing any leukocytes, just antibody.

 

[mercaptovizadeh]

Sorry, this must be confusing, but I think I may understand this a bit better now. If you are giving serum from one individual to another, there are presumably no lymphocytes in it, so the amount of anti-host antibodies in total is very small, and since there are no foreign lymphocytes, no anti-host expansion can occur. Phil Anthropist is right, we wouldn't see a reaction. However, this would only be a passive immunization, it wouldn't protect against the infection for long.

I don't think the MHC is at all an issue, nor are the blood groups. Blood groups are an issue because the host immune system attacks the foreign blood, not the other way around.

This issue crops up with the Rh factor. The mother is primed by the 1st baby's blood, so that she has clonally expanded lymphocytes sensitive to Rh. Then, when she gets pregnant again, these deleterious antibodies are passed to the baby.

This doesn't happen with blood groups since blood groups are sugars and sugars don't induce memory, whereas proteins like Rh, do.

....but I could be wrong yet again!

 

[liverotcod]

#6: the serum will contain antibodies to the bacterium. But it won't contain any of the bacteria, nor the bacterial antigens. The immune donor long ago killed off essentially all of this particular bacterium. So the donated serum won't have the desired effect of raising an immunological response to the bacterium.

 

[DrThom]

#6: the serum will contain antibodies to the bacterium. But it won't contain any of the bacteria, nor the bacterial antigens. The immune donor long ago killed off essentially all of this particular bacterium. So the donated serum won't have the desired effect of raising an immunological response to the bacterium.

 

[DocStretch]

#6: the serum will contain antibodies to the bacterium. But it won't contain any of the bacteria, nor the bacterial antigens. The immune donor long ago killed off essentially all of this particular bacterium. So the donated serum won't have the desired effect of raising an immunological response to the bacterium.

I third that

 

[ellia08]

#6: the serum will contain antibodies to the bacterium. But it won't contain any of the bacteria, nor the bacterial antigens. The immune donor long ago killed off essentially all of this particular bacterium. So the donated serum won't have the desired effect of raising an immunological response to the bacterium.

Passive immunity, while raising no anamnestic response (ie no immunological memory), will give transient immunity to the individual. However, foreign antibodies will be broken down by the immunized individual.

Half life of IgG= ~23 days
Half life of IgA= ~7 days

Examples of passive vaccines preformed in human volunteers: Immune Serum Globulin, Tetanus Immune Globulin, and Rabies Immune Globulin, Rhogam

My Guess: the short term of the immunity renders it impractical to provide protection against bacteria except in rare cases

In other words: ditto to Phil Anthropist

 

[dkang]

just took a vaccine class so i'd have to agree with the last response

adding serum simply introduces antibodies which would provide passive immunity. no immunologic response is initiated. good luck!

 

[Assembler]

It might be true that by having transient immunity (serum with antibodies injected into the recipient), that you would not raise an immunological response to the bacteria since all that is left is proteins specific to the antigens. However, this is an indirect way of not answering the question. I believe the question is presumed on the basis that the recipient is given the serum first, and subsequently infected with that particular type of bacteria (from the environment). The question (IMHO) is asking why would the serum fail to be effective in this case? (The above paragraph was in response to liverotcod)

I had actually considered alloreactivity first as the mechanism of destruction for the antibodies, but I just stumbled upon the fact that I overlooked one key point – these are secreted antibodies not attached to any cells, and therefore, they don’t have MHC complexes. Since there is no difference of MHC complexes, an allogeneic response would not be elicited by CD4 helper cells and CD8 cytotoxic cells.

What will happen is that the antibody itself will function as an antigen to the recipient, and will be degraded via the exogenous pathway of Class II MHC by antigen presenting cells. If it is degraded, it won't be able to confer any sort of immunity, transient or not.

In the event that isn’t correct either, another way of looking at it is to consider the long-term effectiveness of the serum antibodies. As far as I remember, activated B cells differentiate into specific memory cells that secrete only one particular type of antibody (aka plasma cells). The serum antibodies are not attached to cells and would not have this ability to elicit a memory response, since what is normally required is a CD40-CD40L and CD28-B7 interaction between the B cells and T cells - resulting in the secretion of cytokines that would again, induce the differentiation needed to produce memory cells.

Anyway, in the absence of the serum, there are innate systems of immunity that are capable of dealing with this, including T cell independent B1 cells, which often respond to mitogenic bacterial cell wall components (generally secrete IgM). And then, obviously, there is the humoral and cell-mediated response as well.

I really believe it comes down to 2 things: a) the serum antibodies will be destroyed, and b) even if they were not to be destroyed, they have no way of evoking a memory response.

 

[MoosePilot]

Passive immunity, while raising no anamnestic response (ie no immunological memory), will give transient immunity to the individual. However, foreign antibodies will be broken down by the immunized individual.

Half life of IgG= ~23 days
Half life of IgA= ~7 days

Examples of passive vaccines preformed in human volunteers: Immune Serum Globulin, Tetanus Immune Globulin, and Rabies Immune Globulin, Rhogam

My Guess: the short term of the immunity renders it impractical to provide protection against bacteria except in rare cases

In other words: ditto to Phil Anthropist

Nicely worded ditto... wow.

 

[ellia08]

Nah.

Im just a lazy math major who doesnt like the fancy-schmancy english words.

 

[stoic]

like the others have said, you cannot use serum or antibodies from another person/animal to induce a memory response. You can use immunoglobulins to combat acute infection or exposure (thing hepatitis), but the ig molecules are only good until the body recognizes them as "non-self" as destroys them. So in terms of providing long term protection, the serum would have no real activity.