In response to viral infection, the immune systems of mice typically

Question

In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its surface. Mice infected with the herpesvirus generally develop keratitis, a degenerative disease affecting part of the eye. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpesvirus.

Which of the following, if true, most helps to support the scientists’ reasoning?

Which of the following, if true, most helps to support the scientists’ reasoning?

(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.

(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.

(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.

(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice.

CR02830
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BrentGMATPrepNow · Accepted Answer

Step 1: Read the question stem: Which of the following, if true, most helps to support the scientists’ reasoning?
This looks like a Strengthen the Argument question

Step 2: Summarize the argument to yourself so you full understand its structure
 
PREMISE: infection --> antibodies bind to virus' proteins and kills it
PREMISE: mice with herpesvirus develop keratitis in eye
PREMISE: proteins on eye resemble herpesvirus proteins
CONCLUSION:  antibodies to herpesvirus CAUSE keratitis 
 
Step 3: Read each answer choice while reminding yourself of the argument's conclusion.

(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
Does this strengthen the conclusion that  antibodies to herpesvirus CAUSE keratitis ?. 
No. This information has no bearing on the conclusion. 
ELIMINATE

(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.
Does this strengthen the conclusion that  antibodies to herpesvirus CAUSE keratitis ?. 
No. This information actually hurts the conclusion.
ELIMINATE

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.
Does this strengthen the conclusion that  antibodies to herpesvirus CAUSE keratitis ?. 
YES! 
If the herpesvirus is altered, then the antibodies do not cause keratitis. 
This definitely strengthens the conclusion. 
KEEP C

(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.
Does this strengthen the conclusion that  antibodies to herpesvirus CAUSE keratitis ?. 
No. It just tells us that other things may also cause keratitis. That's fine, but it doesn't address whether or not the  antibodies to herpesvirus cause keratitis 
ELIMINATE

(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice
Does this strengthen the conclusion that  antibodies to herpesvirus CAUSE keratitis ?. 
No, this has nothing to do with keratitis
ELIMINATE

Answer: C

Cheers,
Brent

BlacknYellow · Answer

The key to CR questions is to really understand what's going on in the argument.

I recommend boiling down the argument to a couple of sentences using YOUR own words.  
Mice with a certain virus ALSO develop a particular degenerative eye disease. Why? It appears that the antibodies that target the virus (by attaching to its protein) also attack cells in the eye. So the antibodies mistake the proteins on the cells of the eye for those on the virus.

Conclusion: The antibodies are responsible for causing the degenerative eye disease (by using the aforementioned mechanism).

In casual statements one way to strengthen the argument is to remove the cause. If the effect is also absent, then you have a strengthener. 
Choice (C) accomplishes this task. When you remove the suspected cause (the proteins similar to those on the cells of the eye to which antibodies attach), then the effect (Keratitis) is no longer there. In other words, the antibodies are no longer targeting those particular types of proteins similar in both the original herpervirus and the cells of the eye.

Arro44 · Answer

In my opinion the answer should be C as this answer choice picks up on the similarities between Herpes Virus and anti bodies. Hence, if the different strain of the Virus has different cells, the respective antibodies, given they closely resemble the cell structure of the original Virus, would look different than before and thus not cause Keratitis. (My explantion is by no means SC sufficient

)

aragonn · Answer

premise: 
1. In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its(the virus) surface.This is a general responce of a mice in case of a viral infection.
2. Mice infected with the herpesvirus generally develop keratitis, a degenerative disease affecting part of the eye.
3. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpesvirus. 
 ----- Most probable reasoning of scientists to think all this could be that cells react to infection on the basis of surface. as two have close resemblance. it considered this part as virus and coated it with proteins.

Which of the following, if true, most helps to support the scientists’ reasoning?

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.  --- this seems to be the correct answer. as keratitis devlopes on the basis of surfacr of virus. if this given virus has different surface, body cell's find a difference in eye cell and this new virus and so no keratitis will be developed.

gvij2017 · Answer

keratitis are caused by antibodies to the herpesvirus 
Reason: 
proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface

Now, if surface of cell doesn't resemble with surface of herpesvirus, does Keratitis happen. 
If not, it's weakening.

C is close my thinking

C looks like an answer.

MikeScarn · Answer

This is tough one from a reading comprehension perspective IMO.

Premise : The Immune System attacks virus' by attaching to surface area of proteins of the virus.
 Premise : Herpesvirus leads to Keratitis (located in eye).
 Premise : Herpesvirus proteins in the eye are similar to those that cause Keratitis.
 Conclusion : Keratitis is caused by antibodies of Herpesvirus

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.  New strain of Herpesvirus is not located in the eye, and it does not lead to Keratitis? Yep, that strengthens our Conclusion. Keratitis (located in eye) is definitely caused by antibodies of Herpesvirus attaching to the proteins in the eye.

thangvietnam · Answer

excellent explanation
the most challenging to cr is to understand the argument. only when we can paraphrase the complex argument into a simple sentence, we can fully understand the argument. the logic of cr is easy to learn after a few tens questions. 
this argument is complex with many new words. but once we can paraphrase, we can attack it.

causal argument is popular on og books. if argument say that A cause B, we can support it by showing that
when there is no cause, there is no effect. it is the choice C which do this point 
it it not the case that B cause A. there is no reversal causal relation 
there is another case, in which A appear and B appear.

i repeat again that understanding the argument is the main job of doing cr and that logic of cr is much more easier to master .

David nguyen · Answer

Summary:
1. Immune System -> Antibodies kill virus = binding to its surface proteins
2. Mice w/ H-virus -> develop keratitis (eye disease)
3. H-virus surface proteins ~ similar to ~ eye surface protein
Conclusion: Antibodies to H-virus -> caused keratitis

I misunderstood the meaning of the reasoning, leading to confusion. I thought that  (2) Mice w/ H-virus caused keratitis ; however, I was wrong. The correct meaning is that there is a correlation. Mice infected with H-virus GENERALLY develop keratitis — GENERALLY developing keratitis does not imply that H-virus caused keratitis. And I did it again to the conclusion: Antibodies to the herpesvirus means H-virus caused keratitis. The correct meaning is that the Antibodies which were produced to destroy the the virus caused keratitis.

In short, Antibodies misidentified the H-virus surface proteins with Eye surface proteins, causing Keratisits, an eye disease.
 
  P/s:  Can experts help me on how to avoid misunderstanding meaning issue for the next time, please? Thanks.

NikitaVChoudhary · Answer

It is important to consider the cause and effect.As the argument states:
"Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpes virus."
Antibodies(proteins) are causing keratitis .
So, if any statement tells any other kind of proteins doesn't cause Keratitis, then that option would strengthen Scientist's take.
C.Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.
Hence C.

voldemort93 · Answer

Hi,

I've a question regarding the OA. Doesn't the OA assume that the antibodies automatically tend to change with the different strain of the herpesvirus?

GMATNinja · Answer

The OA doesn't assume the antibodies  change  when the mouse contracts the new strain of herpesvirus.

The mouse's immune system will produce a set of antibodies that help fight a virus. If a new strain of herpesvirus is given to the mouse, the mouse will produce a new (and potentially different) set of antibodies.

These new antibodies will match different proteins to the antibodies for the original herpesvirus. This means the new antibodies may not bind to the proteins on the surface of cells in the part of the mouse's eye that is susceptible to keratitis. If the antibodies are unable to bind to these proteins, the mouse will not develop keratitis from the new antibodies.

This helps support the scientists' reasoning that it is the antibodies to the original strain of herpesvirus that are causing keratitis in mice. This is because it is the  similarity  between the surface protein on the  original strain  of herpesvirus and the cells in the mouse's eye that causes the problem. This similarity makes the mouse susceptible to keratitis by the antibodies binding to the surface protein in its eye.

I hope that helps!

TargetMBA007 · Answer

Thanks for the very useful reply.

One question I had, in one of the training courses I took, it mentioned that we should always be looking to support or strengthen the assumption in such questions, as opposed to strengthening or weaking the "conclusion". With this approach, we directly strengthen the conclusion, I would love to have your thoughts on that.

Thanks

sssanskaar · Answer

Dear Experts / ChiranjeevSingh / CrackVerbalGMAT / AjiteshArun / VeritasKarishma / GMATNinja

Can someone please explain why option D is incorrect in this question but the very same answer is correct in https://gmatclub.com/forum/in-response- ... 23564.html, even when both the questions are aksing to strengthen the argument and the argument passage is the same?

I am sure that I am missing something here and I want to address it. :)

CEdward · Answer

In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its surface. Mice infected with the herpesvirus generally develop keratitis, a degenerative disease affecting part of the eye. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpesvirus.

Which of the following, if true, most helps to support the scientists’ reasoning?

P: Immune systems of mice produce antibodies against virus
P: Antibodies destroy the virus by binding to proteins on the virus’s surface
P: Mice infected with herpes generally develop keratitis
P: Proteins on the surface of eye cells resemble those on the herpes virus
C: Keratitis is caused by antibodies to the herpesvirus

Cause (antibodies to herpes) > Effect (keratitis)

Which of the following, if true, most helps to support the scientists’ reasoning?

(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
-tempting trap choice, but choice fails to fully acknowledge the reasoning that antibodies cause keratitis

(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.
-weakens the conclusion since we see that the effect (keratitis) does not necessarily occur when the cause (antibodies to herpes) is present

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.
Correct. The key premise of the argument is that antibodies are produced in response to the surface proteins and because the proteins on the eye cells resemble those on the herpesvirus’s surface the mice get keratitis. So, if it turns out that the eye proteins DO NOT resemble the surface proteins of the new strain which antibodies are produced to fight off, then we should expect not to see keratitis.

(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.
-weakens the argument b/c the cause is eliminated and yet the effect still exists …antibodies produced against those herpesvirus would no longer be around since there is no infection
(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice.
-rate of infection is out of scope

Anisha1637 · Answer

As the argument concludes keratisis is developed due to the production of antibodies in response to herpes virus, Option C clearly strengthens the conclusion as it suggests that the new strain of herpes virus doesn't result in development of keratisis.

hanyi · Answer

C tells us that different proteins do not cause the disease, strengthening the conclusion

aumd568 · Answer

In Mice,
To destroy viral infection, immune system → attach → proteins on virus’s surface
Herpes → Eye Problem
Proteins in eye → similar to → Proteins in herpes virus
 Conclusion : Antibodies mistake the proteins in eye for the virus and cause eye problem

(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
 
→ We don’t really know if this leads to any side effect and if the anti bodies get mixed up with those proteins

(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.

→ We do not know much about the cause of keratitis here. If anything this weakens the argument by telling us that there are cases where antibodies have been formed but keratitis does not develop

(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.

→ This clearly tells us that antibodies mistook the protein in the eye for herpes virus since for the new strain of the herpes virus, they did not see any development of keratitis

(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.

→ Weakens the argument. This tells us that there is some other reason for keratitis that is independent of the herpes virus.

(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice.

→ We are not really concerned with rate of contracting herpes or antibodies not forming. We care about what are the side effects of antibodies forming.

Option C is the answer

Ahmed9955 · Answer

Regards, 
Ahmed
In case there's an error in my reasoning, please do correct me. Otherwise Kudos.

jabhatta2 · Answer

Hi  avigutman  - I did get this correct.

My question are more  generic , regarding what do you infer as you read along vs wont CANT YOU INFER as you read along.

A) When you read the  blue  followed by the  pink

Do you assume : The antibody is attaching itself to the proteins on the surface of eye cells ( similarly  to what the antibody does with herpesvirus proteins)

OR

Should we not assume that ?

I personally thought, we could not assume that.

I am looking for why the 'presence of anti-bodies' causes the  keratitis  ? But i think we need to comfortable not knowing why exactly

In response to viral infection, the immune systems of mice typically

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In response to viral infection, the immune systems of mice typically

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