29. ELISA is widely used as the initial screening test for diseases such as HIV,

Question

29. ELISA is widely used as the initial screening test for diseases such as HIV, lupus, and Lyme disease. How would western blot be used in the diagnostic workflow?

30. Protein markers from Lyme disease, lupus, or syphilis that may cause a false positive result in an ELISA HIV test are unlikely to have the same molecular mass as an HIV antigen. What must be done if an ELISA test has a pos. result?

31. In blocking solution PBS –
a. helps keep nonspecifically bound antibody from attaching to the membrane
b. can randomly adhere to the membrane and obscure or weaken the specific antibody c. provides the ideal pH and salt conditions for maintaining milk protein binding integrity d. will be 5% nonfat dried milk power

32. An Antigen is –
a. one of the essential myosin light chains
b. any substance that is recognized by the antibody
c. a detergent that helps keep nonspecifically bound antibody from adhering to the membrane d. obscure and will weaken a specific antibody

33. What happens when myosin hydrolyzes ATP?

34. What is happening in this diagram?

Explanation / Answer

Please find the answers below:

Answer 29: ELISA remains a primary diagnostic method for detecting presence of diseases such as HIV, lyme disease, lupus etc. All these diagnoses are based upon detecting the presence of a particular antigen or antibody in the system specifically against that disease. Howevever, since ELISA requires multiple handling steps, it remains advisable to conduct a confirmatory assay such as western blotting for such investigations. In order to perform it, the affected tissues can be directly excised from the subject and the protein isolated from them can be subjected to western blot detection using monoclonal antibodies.  

Answer 30: If ELISA gives a false positive result for HIV and masks it for Lyme disease or lupus, a confirmatory assay such as western blotting or direct PCR should be performed to investigate the presence of the protein or DNA/RNA markers associated with these disease, respectively.

Answer 31: Choice c: PBS provides the ideal conditions of buffered pH and salts which enhance the binding of various proteins in the skimmed milk/blocking agent to improve the quality of results.

Answer 32: Choice b : antigens are those immunogens which are recognized by host immune system and antibodies are generated/released against them. If the infection has taken place repeatedly in the host, the already present antibodies will recognize the antigen and bind to it.

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