Syphilis IgG Antibody with Reflex, Serum
Method Description Describes how the test is performed and provides a method-specific reference
The BioPlex Syphilis IgG is a multiplex flow immunoassay performed on the BioPlex 2200 System (Bio-Rad Laboratories, Hercules, CA). Three types of dyed beads are coated with recombinant proteins associated with Treponema pallidum (15kDa, 17kDa and 47kDa). An aliquot of patient sample, sample diluent, and bead reagent are combined in a reaction vessel, and the mixture is incubated at 37 degrees C. After a wash cycle, antihuman IgG antibody conjugated to phycoerythrin (PE) is added to the dyed beads, and this mixture is incubated at 37 degrees C. Excess conjugate is removed in another wash cycle and beads are resuspended in wash buffer. The bead mixture is then passed through a flow-based detector and identified according to the fluorescence emitted, which is specific to the internal dye composition of the microsphere. The amount of antibody bound to the capture antigen is then determined by measuring the fluorescence of the attached PE. Raw data is calculated in relative fluorescence intensity (RFI).(Package insert: BioPlex 2200 System Syphilis IgG [T.pallidum], Bio-Rad Laboratories Clinical Diagnostic Group, Hercules, CA)
If the IgG result is positive, a rapid plasma regain (RPR) is automatically performed. The RPR test is a macroscopic screening assay done with unheated serum. Reagin reacts with nontreponemal antigen containing colloidal charcoal particles. This reaction results in a visual flocculation of the black particles against the white card background. The test yields a positive or negative result, and all positive samples are titered to determine the highest positive dilution.(Huber TW, Storms S, Young P, et al: Reactivity of microhemagglutination, fluorescent treponemal antibody absorption, Venereal Disease Research Laboratory, and rapid plasma reagin tests in primary syphilis. J Clin Microbiol 1983 Mar;17:405-409)
The Serodia TP-PA test is based on the agglutination of colored gelatin particle carriers sensitized with Treponema pallidum (Nichols Strain) antigen. Serum samples are serially diluted in microplate wells. Sensitized gelatin particles are added to respective wells and the contents of the plate mixed. The mixture is incubated for 2 hours at room temperature. Serum containing specific antibodies will react with the antigen-sensitized colored gelatin particles to form a smooth mat of agglutinated particles in the microplate well. A compact button formed by the settling of the non-agglutinated particles characterizes negative reactions. The agglutination patterns are read visually to determine interpretation.(Package insert: Serodia -TP PA, Fujirebio Diagnostics, Inc., Tokyo, Japan.)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 9 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test