Multiplex Detection of IgM and IgG Class Antibodies to<i>Toxoplasma gondii</i>, Rubella Virus, and Cytomegalovirus Using a Novel Multiplex Flow Immunoassay

The measurement of cytomegalovirus (CMV) IgG avidity is a powerful tool for identifying individuals with recent CMV infection. Because such patients are expected to be positive for CMV IgM, several investigators have suggested that CMV IgG-positive sera first be screened for CMV IgM and then only the IgM-reactive sera be tested for avidity. We investigated the impact of different CMV IgM assays on such a reflexing algorithm using a panel of 369 were IgM negative by BIFA, 10 by ELFA, and 15 by EIA and CIA. In both these avidity groups, BIFA IgM-negative sera were also negative by the other 3 assays. These findings demonstrate that an algorithm requiring CMV IgM reactivity as a criterion for CMV IgG avidity testing does not identify all low-avidity sera and thus misses some cases of acute CMV infection.

Section: Discussionsupporting

confidence: 77%

Potential Impact of Different Cytomegalovirus (CMV) IgM Assays on an Algorithm Requiring IgM Reactivity as a Criterion for Measuring CMV IgG Avidity

Prince

Lapé-Nixon

Brenner

et al. 2014

“…This analyzer can detect different antibodies in a single tube, thus yielding highthroughput multiplexing analysis, saving time and preventing errors of result transmission. To our knowledge, only one study assessed the ToRC IgG and IgM immunoassays for toxoplasmosis serodiagnosis (6). In that study, the BioPlex 2200 ToRC IgG assays demonstrated a high agreement of 98.7% (592/600 specimens) with the routine practice used by the authors, while the ToRC IgM assays yielded an agreement of 91.2% (547/600 specimens).…”

Section: Discussionmentioning

confidence: 94%

“…The BioPlex 2200 ToRC IgG and IgM immunoassays already met these criteria in a prospective study on 600 serum samples subjected to routine testing (6). In another study, elevated sensitivity of IgM antibodies produced by recent infections was demonstrated (10).…”

mentioning

confidence: 99%

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Performance of the BioPlex 2200 Flow Immunoassay in Critical Cases of Serodiagnosis of Toxoplasmosis

Guigue

Menotti

Hamane

et al. 2014

The BioPlex 2200 automated analyzer (Bio-Rad Laboratories, Hercules, CA) is a recently developed multiplex analyzer that enables the detection of anti-Toxoplasma, -rubella, and -cytomegalovirus antibodies in the same assay. The aim of this study was to compare this new technology (using the BioPlex 2200 ToRC IgG/IgM kit) in critical cases of serodiagnosis of toxoplasmosis (acute, chronic, or congenital infections and cases with discrepant results) to the technologies used in our routine practice, i.e., the Platelia IgG/IgM enzyme-linked immunosorbent assays (ELISAs) (Bio-Rad Laboratories) and the Toxo-Screen direct agglutination assay (bioMérieux, Lyon, France). Overall, most cases of false-positive/negative results obtained with the Platelia IgG or Toxo-Screen assay were corrected by the BioPlex 2200 ToRC IgG (87.5%). Furthermore, the analysis of 35 sequences of sera showed a trend toward a more rapid decrease of IgM titers by BioPlex 2200 than by Platelia. These results for IgM detection can be explained by a weaker detection of residual IgM. Indeed, among 23 serum samples from patients with probable past infection with long-lasting IgM (Platelia M positive and IgG avidity index, >0.5), the BioPlex 2200 Toxoplasma IgM assay was positive for only 11 serum samples. In our panel of critical cases comprising 156 serum and 6 cord blood samples from 103 patients with acute, chronic, or congenital infection, the BioPlex 2200 IgG assay was a sensitive (97.8%) and specific (91.3%) method for IgG detection. The high specificity (97.4%) of IgM detection combined with the shorter kinetics of IgM titers may considerably reduce the number of residual IgM detections, thus yielding more precise diagnoses of acute infections. Infections due to the protozoan parasite Toxoplasma gondii are highly prevalent among humans and animals worldwide and are responsible for severe complications in immunocompromised patients and in children born to infected mothers. Diagnosis of this infection is therefore important not only for treatment but also for epidemiology and prevention (1). The use of serologic tests to search for anti-T. gondii antibodies is a primary method of diagnosis (2). Different commercial serologic tests are available and possess unique patterns of increases and decreases with time after infection (3-5). The tests most commonly used in routine laboratories for the detection of anti-T. gondii IgG are the doublesandwich enzyme-linked immunosorbent assay (ELISA), the indirect fluorescent-antibody assay (IFA), the indirect hemagglutination assay, and the direct agglutination test. For anti-T. gondii IgM, the most common tests are the double-sandwich ELISA, the immunosorbent agglutination assay (ISAGA), and the IFA. Nevertheless, these techniques have certain disadvantages, such as significant hands-on time or low throughput (6).The recently developed BioPlex 2200 automated analyzer (BioRad Laboratories) is a multiplex flow immunoassay (MFI) that enables the simultaneous detection and identification of multiple antibodies in ...

“…All available panel 3 samples that were negative or equivocal for CMV IgG by the Wampole assay were tested for CMV IgG using an FDA-cleared chemiluminescent immunoassay (CIA) (Immulite, Siemens Diagnostics, Los Angeles, CA) (20). In all panel 2 samples and in CMV IgG-positive panel 3 samples, CMV IgM was measured with an FDA-cleared magnetic bead-based flow cytometric immunofluorescent assay (21), performed per the manufacturer's instructions (BioPlex 2200; Bio-Rad Laboratories, Hercules, CA). For this study, equivocal CMV IgM results were considered positive.…”

Section: Methodsmentioning

confidence: 99%

Performance of a Cytomegalovirus IgG Enzyme Immunoassay Kit Modified To Measure Avidity

Prince

Lapé-Nixon

Novak-Weekley³

2014

bThe measurement of cytomegalovirus (CMV) IgG avidity accurately discriminates recent and past CMV infections. We sought to determine if the Wampole Laboratories CMV IgG enzyme immunoassay (EIA) could be modified to measure avidity. The evaluation panel consisted of 156 serum samples we used in 2002 to validate a laboratory-developed EIA, in which 78 serum samples exhibited low avidity, 7 exhibited intermediate avidity, and 71 exhibited high avidity. The qualitative agreement between the two avidity assays was 94% (147/156); all 9 sera with discordant results exhibited intermediate avidity in one of the assays. The avidity index (AI) values in the two assays showed excellent correlation (r ‫؍‬ 0.96, P < 0.0001). The definition of high avidity was verified for the Wampole assay by demonstrating high avidity in 91/93 (98%) recently collected CMV IgG-positive/IgM-negative serum samples. The performance of the Wampole avidity assay in a reference laboratory setting was assessed using 470 consecutive serum samples submitted for CMV IgG avidity testing. Surprisingly, 101 serum samples were negative when screened for CMV IgG using the Wampole kit per the package insert; 98 of these 101 serum samples were tested using a CMV IgG chemiluminescent immunoassay, and only 5 were positive. Of the 369 CMV IgG-positive samples, 6% exhibited low IgG avidity, 6% exhibited intermediate avidity, and 88% exhibited high avidity; CMV IgM detection rates were inversely related to AI levels. These findings show that (i) the Wampole CMV IgG EIA can be modified to measure CMV IgG avidity, (ii) many samples are apparently submitted for avidity testing without knowledge of their CMV IgG status, and (iii) most CMV IgG-positive sera submitted for avidity testing exhibit high avidity. T he accurate discrimination of primary cytomegalovirus (CMV)infection from reactivation or reinfection plays an important role in the clinical management of pregnant women (1-5). Primary CMV infection during pregnancy may lead to intrauterine infection of the fetus, which is associated with hearing loss, blindness, and mental retardation (6-8). In contrast, CMV reactivation or reinfection during pregnancy is rarely associated with intrauterine fetal infection (2, 7). The accurate identification of primary CMV infection is also important in managing solid organ transplant recipients, who exhibit an increased risk of organ rejection following primary CMV infection (9-11).Over the last decade, the assessment of CMV IgG avidity has become the preferred laboratory tool for identifying patients with primary CMV infection (4, 5). IgG avidity gradually matures over time, so that IgG detected by 5 to 6 months after a primary infection exhibits high avidity; thus, a low CMV IgG avidity result is a strong indicator of primary infection within the preceding 5 to 6 months (2, 3, 6, 12, 13). CMV IgG avidity is more accurate than CMV IgM detection for identifying primary infection, since CMV IgM persists for Ͼ6 months in some patients (2,7,14).In 2002, we validated a laboratory...