CASE STUDY #7: An enzyme-linked immunosorbent assay (ELISA) for hepatitis 8 viru
ID: 281517 • Letter: C
Question
CASE STUDY #7: An enzyme-linked immunosorbent assay (ELISA) for hepatitis 8 virus (HBV) was performed on serum from 12 different undergraduates. Only students A and B were positive for lgG against the surface antigen of the virus. Student A was from Nigeria and student B was a Uniteid States citizen. Both were similar in age, race and overall good health, but from different cultural lifestyles. 28. The initial ELISA test for exposure to the hepatitis B virus is limited in that it: A. cross reacts with many other viral infections B. does not distinguish HBV from other hepatitis viruses C. does not distinguish between HBV-infected individuals and those vaccinated against HBV D. requires a large sample ( >20cc ) of serum E. is least sensitive than a complement fixation assay 29. A test that would distinguish a recent exposure to HBV from long-past (9 months) exposure to the virus could involve detection of: A. anti-core (IgG) antibody B. anti-polymerase (IgG) antibody C. anti-core (lgM) antibody D. anti-e (lgG) antibody E. anti-x (lgG) antibody 30. If student A had been vaccinated for HBV, and had not been exposed to the active virus, his antibody titer nine (9) months later would most likely show only antibody against the: A. core antigen B. polymerase antigen C. envelope lipid D. nucleic acid E. surface antigen 31. Known mechanisms of transmission of the HBV includes all of the following except: A. contaminated blood B. organ transplants C. penile-vaginal sex D. penile-anal sex E. aerosol (droplet) inhalationExplanation / Answer
Answer 31) HBV infection involves all execept aerosal infection.
Because HIV, HBV and HCV do not spontaneously pentetrate intact skin and airborne transmission of these viruses does not occur.
Answer 30) It will show antibody against surface antigen.
Because: To determine if you have an acute or chronic infection, you must be tested for hepatitis B over a six-month period. The specific test that indicates if you are infected is the hepatitis B surface antigen (HBsAg) test. This antigen covers the surface of the virus and usually there are lots of HBsAg in your blood when you’re infected. If you test positive for HBsAg for longer than six months, it means you have a chronic hepatitis B infection.
But, if you no longer test positive (or “reactive”) for HBsAg after six months and you develop hepatitis B surface antibodies (HBsAb), then you have cleared hepatitis B after an “acute” infection.
Answer 29) anti e antibody.
Answer 28) option c
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