Question

25. Testing for heterophile antibodies is specific for the infectious mononucleosis virus. (True or False) 26. To determine whether a patient had an IgG antibody to a specific antigen, an agglutination test was performed. The undiluted patient's sera was negative for agglutination as were all dilutions made. a. patient is negative for the antibody. b. patient sera is exhibiting prozone through the very diluted dilutions made. c. patient sera is unable to form a lattice d. patient is positive for the antibody. 27. Lack of agglutination in a hemagglutination inhibition test indicates: a. positive result- b. antibody not bound to labeled enzyme. c. negative result d. too much substrate used and left on the plate too long.

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Answer 1

A25) TRUE, As heterophile antibodies test provides 100% true result for infectious mononucleosis virus ( Epstein-Barr Virus (EBV) ).

A26) B patient sera is exhibiting prozone through the very diluted dilutions made.

A27) A positive result .

Components Interaction Microtiter Results RBCs No Reacti Hemaggluti Virus RBCS Hemagglutination Virus Antibody Hemagglutination Inhibition +RBCSO

The nucleic acids of various viruses encode surface proteins (e.g.hemaaglutinin (HA) of influenza virus) that agglutinate red blood cells (RBC) of a variety of species. The reaction of viral hemagglutinins with red blood cells results in a lattice of agglutinated cells which settle irregularly in a tube or microtiter well. Unagglutinated cells settle in a compact button. This process is known as hemagglutination.

Hemagglutination occurs when measles viruses and red blood cells are mixed . But, if the serum of a person infected with measles virus is mixed with RBC and measles virus, there won’t be any agglutination of RBC. This phenomenon is known as hemagglutination inhibition. This arises because antibodies present in the serum of that infected person reacts with the measles viruses and neutralize them (positive result).

If the patient’s serum do not contain antibodies against surface proteins of test virus, there will be presence of hemagglutination as surface molecules are free to hemaaglutinate RBCs (negative result).