What is Postzone effect?
What is Postzone effect?
The Post-zone Phenomenon is a false-negative test caused by excessive antigen, relative to antibodies, which prevents antibody-to-antigen crosslinking [4]. Crosslinking is necessary for immunochromatographic detection [4].
What causes Prozone effect?
The prozone phenomenon, seen during primary and secondary syphilis, occurs because a higher than optimal amount of antibody in the tested sera prevents the flocculation reaction typifying a positive result in reagin tests. Serum dilution is necessary to make the correct diagnosis.
Why is it called the hook effect?
Because immunoassays are calibrated in the linear range, the reported concentration for this sample is “a”, which is lower than the real concentration “b”. This is called the Hook effect and only exists in one-step heterogeneous immunoassays.
What is Prozone effect in agglutination?
However, excess antibodies in a serum sample can inhibit the antigen-antibody interaction and subsequent agglutination reaction, leading to a false negative result, which is known as a prozone phenomenon or effect (Tizard 2004).
What is a Prozone and Postzone phenomenon?
The prozone reaction refers to the absence of antibody-antigen precipitation in the presence of antibody excess. Since the authors refer to situations of antigen excess, the term prozone cannot correctly be used. Instead, absence of precipitation with excess antigen is described as the postzone phenomenon.
What is Zone phenomenon?
: the occurrence of prozones in antibody-antigen mixtures.
How do you stop Prozone effect?
Sequential addition of antigen and antibody, paired with stringent washing, can prevent the effect, as can increasing the relative concentration of antibody to antigen, thereby mediating the effect.
What is Postzone in immunology?
The postzone is the comparable zone of antigen excess.In some titrations, however (such as the slide latex agglutination test for cryptococcal antigen), antigen is varied in the presence of a constant amount of antibody (Fig 2, bottom).
What is zone of equivalence?
Definition of equivalence zone : the part of the range of possible proportions of interacting antibody and antigen in which neither or but small traces of both remain uncombined in the medium.
What is the prozone effect?
The range of relatively high antibody concentrations within which no reaction occurs is called the prozone. The effect can also occur because of antigen excess, when both the capture and detection antibodies become saturated by the high analyte concentration.
What is the prozone phenomenon in antibody excess?
In the case of antibody excess, the prozone phenomenon occurs, in which antigen combines with only one or two antibody molecules, and so no cross-linkages are formed.
What is the zone of influence of a project?
Zone of Influence means an area within which there are positive or negative effects as a result of the Project. Zone of Influence means the spatial area or volume of receiving water flow within which some degradation of water quality or use impairment is anticipated to occur as a result of a discharge.
What is the meaning of pro zone in biology?
/pro·zone/ (pro´zōn) the phenomenon exhibited by some sera, in which agglutination or precipitation occurs at higher dilution ranges, but is not visible at lower dilutions or when undiluted.
