Prozone phenomenon is due to:

Ans: B (Antibody excess) Ref: Ananthonaravan. Panikar CJ Textbook of .Microbiology. 8th Edition. John Wiley & Sons: 2009. Pg. 104Explanation:Antigen and antibody can combine in various proportions.State of antibody excess - ProzoneOptimal ratio - Zone of equivalenceState of antigen excess - Postzone (See the following figure)The prozone is very important in serodiagnosisSera rich in antibody may sometimes give a false negative precipitation or agglutination resultE.g. Patients with Brucellosis are known to exhibit prozone phenomenonThe serum should be diluted several times when prozone phenomenon is suspected