AAMC #10 - Question 113?!

[MedicalMan14]

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Can anyone explain why the answer is B, I do not understand AAMC's explanation. My understanding is that antibodies would be produced for the kidney disease hantavirus only, as this is the only factor which seems to elicit a 'positive immunological reaction' in Experiment 1.

"A is not the best answer because these antibodies were not specific for only the kidney disease-causing hantavirus; they were specific for the pulmonary disease-causing hantavirus as well."
- Where in the passage does it show being specific for the pulmonary disease causing hantavirus?

 

[addo]

It says "patients' sera were mixed with known pathogenic viruses. A positive immunologic reaction was seen with hantavirus..."

The sera was mixed with several known bacteria and viruses, among them being the hantavirus. The sera contained the unknown pathogen, and antibodies against it. When the antibodies were mixed with the hantavirus, there was a reaction because the unknown pathogen's antibodies recognized the hantavirus, meaning that the hantavirus was antigenically similar to the unknown pathogen.

I dont know if im being clear, but B definitely makes sense. A does not because the patients did not have kidney disease, so they wouldnt have hantavirus antibodies. To reiterate, the only reason there was an immunologic reaction was that the unknown pathogen was sufficiently similar to hantavirus for there to be an immunologic reaction with the unknown pathogen's antibodies.

 

[MedicalMan14]

I still don't understand. First of all all it says is ; Patient' sera were mixed with KNOWN pathogenic viruses and bacteria. A a positive immunologic reaction was seen with a hantavirus that causes kidney disease."

How can I conclude; 1 that the sera had antibodies to the unknown pathogen (what is unknown ; it says they are KNOWN), and how do I know that it is antigenically related to the known hantavirus. If an antibody recognizes an antigen; that doesn't mean its antigenically related to it. I am severely confused.

 

[GASPER20]

I still don't understand. First of all all it says is ; Patient' sera were mixed with KNOWN pathogenic viruses and bacteria. A a positive immunologic reaction was seen with a hantavirus that causes kidney disease."

How can I conclude; 1 that the sera had antibodies to the unknown pathogen (what is unknown ; it says they are KNOWN), and how do I know that it is antigenically related to the known hantavirus. If an antibody recognizes an antigen; that doesn't mean its antigenically related to it. I am severely confused.

i got this wrong as well.

usually antibodies and antigens are very specific to a certain strain of a species but in this case the antigen they discovered was a hallmark belonging to all hantaviruses species and not to any strain in particular.

the patients participating in the experiment were inflicted with pulmonary disease, not kidney-disease.

they incubated the patients' antibodies to a slew of different KNOWN viruses/bacteria that they already had on file in order to figure out which was the disease causing pathogen.

the antigen they discovered just happened to be related to the kidney hantavirus. the immunological assay did not detect a pulmonary hantavirus because they did not discover such a pathogen yet! usually when you have no suspecting pathogen for a disease, you do a shot-gun analysis to figure out the closest relative. it this case it lead them to the discovery of a new hantavirus strain -the pulmonary disease causing one.

hope that makes the correct answer a little easier to digest.

 

[MedicalMan14]

Thank you that helps alot.