Decay of Passively Acquired Maternal Antibodies against Measles, Mumps, and Rubella Viruses

The decay of maternally derived antibodies to measles, mumps, and rubella viruses in Swiss infants was studied in order to determine the optimal time for vaccination. A total of 500 serum or plasma samples from infants up to 2 years of age were tested by enzyme-linked immunosorbent assay and fluorescent-antibody testing. The decline of antibody prevalence was slowest against the measles virus. By 9 to 12 months of age, only 5 of 58 (8.6%; 95% CI, 2.9 to 19.0) infants were antibody positive for the measles virus, and only 2 had levels above 200 mIU/ml. Mumps and rubella virus antibody seropositivity was lowest at 9 to 12 months of age with 3 of 58 (5.2%; 95% CI, 1.1 to 14.4) infants and at 12 to 15 months with 1 of 48 (2.1%; 95% CI, 0.1 to 11.1) infants, respectively. Concentrations of passively acquired antibodies decreased rapidly within the first 6 months of life. We observed no significant differences in antibody prevalence or concentration according to gender in any age group. In conclusion, MMR vaccination at 12 instead of 15 months of age could reduce the pool of susceptible subjects in infancy and support the efforts to eliminate these infections, particularly in combination with a second vaccine dose before school entry.     

Decline of Measles-Specific Immunoglobulin M Antibodies after Primary Measles, Mumps, and Rubella Vaccination

Detection of measles-specific immunoglobulin M (IgM) has become the standard diagnostic method for laboratory confirmation of measles. In outbreaks, the interpretation of an IgM-positive result can be complicated when persons with suspected measles receive a dose of measles vaccine as part of outbreak control measures. This investigation evaluated the decay of measles-specific IgM antibodies 1 to 4 months after primary vaccination with measles, mumps, and rubella vaccine (MMRII). Serum samples were obtained from 536 infants vaccinated when they were 15 months old as part of a study to assess primary and secondary measles vaccine failure. Sixty serum specimens per week were selected from specimens collected between 4 and 9 weeks after MMRII vaccination; all 176 available serum specimens collected between 10 and ≥16 weeks were included. Specimens were tested for the presence of measles-specific IgM by an antibody-capture enzyme immunoassay. The proportion of IgM-positive specimens dropped from 73% at 4 weeks after vaccination to 52% at 5 weeks after vaccination and then declined to 7% by 8 weeks after vaccination. Less than 10% of children remained IgM positive between 9 and 11 weeks. An IgM-negative result helps rule out the diagnosis of measles in a person with suspected infection and a history of recent vaccination. The interpretation of a positive IgM result from a person with a clinically suspected case of measles and a recent history of measles vaccination (especially within 8 weeks) is problematic, and the diagnosis of measles should be based on epidemiologic linkage to a confirmed case or on detection of wild-type measles virus.     

Effect of Multiple Freeze-Thaw Cycles on Detection of Measles, Mumps, and Rubella Virus Antibodies

We investigated the effect of multiple freeze-thaw cycles on mumps, measles, and rubella virus serum antibody levels with whole-virus immunoglobulin G enzyme-linked immunoassays. Fresh serum samples from nine healthy adult volunteers were divided into six sets of five aliquots each. Samples were taken through a total of 10 freeze-thaw cycles and stored at 4°C until assayed. Each assay measurement was done in replicates of five, and the mean value was reported. After completing 10 freeze-thaw cycles, we found no clinically or statistically significant effect on measured antibody levels and found no discernible detrimental effect on the ability to measure these antibodies by enzyme-linked immunoassays.     

Seroprevalence of measles, rubella, and mumps antibodies in Catalonia, Spain: results of a cross-sectional study

Determination of antibody levels against vaccine-preventable diseases is of great value to assess immunization programmes. The objective of this study was to determine the prevalence of measles, rubella, and mumps antibodies in representative samples of the child and adult population of Catalonia and compare the findings to those obtained in 1996. A representative sample of the child and adult (≥15 years) population of Catalonia was studied. Enzyme-linked immunosorbent assay techniques were used to determine the presence of antibodies. Equivocal results for antibodies against measles and rubella were tested using an immunofluorescence technique. To compare proportions, the chi-square test and the Fisher’s exact test were used. Statistical significance was set at 0.05. Adjusted odds ratios were calculated using multiple logistic regression analysis. Samples from 2,619 people were analyzed. The global prevalence of antibodies was 98.3% for measles, 91.1% for mumps, and 98.1% for rubella. The prevalence of rubella antibodies was higher in women than in men (98.8 vs. 97.2%, respectively). Compared with the results obtained in the 1996 seroprevalence study, only the prevalence of rubella antibodies showed a statistically significant increase in men (97.2 vs. 94.6%; p=0.002) and, in particular, in women (98.8 vs. 95.3%; p<0.001). The low prevalence of susceptible subjects has already led to the elimination of indigenous measles in Catalonia and should allow the elimination of indigenous rubella by 2005. The level of antibodies necessary to interrupt the transmission of mumps has still not been reached in all age groups.     

Development of a Bead-Based Multiplex Immunoassay for Simultaneous Quantitative Detection of IgG Serum Antibodies against Measles,Mumps, Rubella,and Varicella-Zoster Virus

Enzyme-linked immunosorbent assay (ELISA) is normally used to quantify the amount of serum IgG antibodies against measles, mumps, rubella, and varicella-zoster virus (MMRV). However, this method is time- and material-consuming. Therefore, a multiplex immunoassay for the simultaneous quantitative detection of antibodies against MMRV was developed. In-house as well as commercially available antigens can be used, making the assay available for all laboratories. The multiplex assay is much more sensitive than the separate ELISAs and has a high specificity, and only 5 μl of serum is needed. Heterologous inhibition did not exceed 11.5%, while homologous inhibition varied between 91.3 and 97.9%. Good correlations with the in-house ELISAs for measles (R² = 0.98), mumps (R² = 0.97), and rubella (R² = 0.97) virus as well as with the ELISA kit for varicella-zoster virus (R² = 0.95) were obtained. In conclusion, the MMRV multiplex assay is a good alternative to the conventional ELISAs and suitable for use in serosurveillance and vaccine studies.     

Seropositivity Rates for Measles,Mumps, and Rubella IgG and Costs Associated with Testing and Revaccination

Retrospective analysis of IgG test results and patterns for measles, mumps, and rubella revealed generally high seropositivity rates, with that of mumps being the lowest. A simplified cost analysis shows that when there is a suspicion of nonimmunity, serological testing may be cheaper than vaccination.     

Evaluation of the Bio-Rad BioPlex Measles, Mumps, Rubella, and Varicella-Zoster Virus IgG multiplex bead immunoassay

The goal of this study was to compare the BioPlex 2200 measles, mumps, rubella, and varicella-zoster virus (MMRV) IgG multiplex assays (Bio-Rad Laboratories, Hercules, CA) to routine testing by enzyme immunoassay (EIA). Serum specimens (n = 500) submitted to our reference laboratory for routine MMRV IgG testing by EIA were also tested by the BioPlex assays. Following testing, the BioPlex measles, mumps, rubella, and varicella-zoster virus assays demonstrated agreements of 91.6% (95% confidence interval [CI], 88.8% to 93.7%), 94.2% (95% CI, 91.7% to 95.7%), 94.4% (95% CI, 92.0% to 96.1%), and 91.8% (95% CI, 89.0% to 93.9%), respectively, compared to the results of EIA. Timing studies showed that the BioPlex MMRV assay could provide complete analysis of 100 serum specimens in 1.7 h, compared to 5.5 h by EIA. These data indicate that the BioPlex MMRV IgG assays exhibit comparable performance (93% overall agreement [1,860/2,000 results]; κ = 0.67) to routine testing by EIA. The BioPlex assays allow for the simultaneous detection of all four analytes, thereby eliminating potential aliquot errors and reducing turnaround time.     

Sleep Patterns among South Korean Infants and Toddlers: Global Comparison

The purpose of this study was to examine sleep patterns in a large sample of infants and toddlers (ages birth to 36 months) in Korea, and to compare sleep patterns, sleep problems, sleep ecology, and parental behaviors to global sleep data on young children in both predominately Asian (P-A) and predominately Caucasian (P-C) countries/regions. We additionally examined parent and child demographic information, parental behaviors, and aspects of the sleep ecology as predictors of sleep patterns among infants and toddlers in Korea. Parents/caregivers of 1,036 Korean infants and toddlers completed an expanded, internet-based version of the brief infant sleep questionnaire. Consistent with other studies of sleep in early childhood, sleep/wake patterns became increasingly consolidated with older child age for the Korea sample. Compared to both P-A and P-C infants and toddlers, children in Korea had the latest bedtimes, shortest total sleep and daytime sleep durations, and the least frequent rates of napping. Even though half of parents perceive their children’s sleep problematic, parental perceptions of severe child sleep problems were the lowest. Within Korea, breastfeeding and bottle-feeding at sleep resumption were associated with increased nocturnal awakenings. Evening television viewing was associated with later bedtimes, which may have implications for sleep hygiene recommendations in clinical practice. The current study provides important information about sleep/wake patterns, parental behaviors, and aspects of the sleep ecology for infants and toddlers for physicians to support healthy sleep in Korea.     

Multiple Sclerosis: Local Synthesis of Electrophoretically Restricted Measles, Rubella, Mumps and Herpes Simplex Virus Antibodies in the Central Nervous System

An imprint electroimmunofixation (IEIF) technique was used to study measles, rubella, mumps and herpes simplex virus antibodies in serum and concentrated cerebrospinal fluid (CSF) from ten patients with multiple sclerosis (MS). Electrophoretically restricted virus-specific antibodies were detected in sera or CSF from nine of the ten patients. Comparison of the antibody patterns in matching serum and CSF samples indicated that electrophoretically restricted populations of antibody against one or more of the four viruses were produced locally in the central nervous system of nine patients. No association between the locally produced antibody populations the oligoclonal IgG of the CSF could be demonstrated. The virus-specific antibodies studied thus seem to constitute only a minor fraction of the total IgG of the CSF from MS patients.     

天津市育龄妇女血清中抗风疹病毒抗体分析

测定了天津市区１５３名正常育龄妇女和１０３名有异常孕产史妇女血清中抗风疹病毒（ＲＶ）ＩｇＧ抗体，对其中１８７名妊娠妇女测定了特异性ＩｇＭ。结果显示，正常育龄妇女ＲＶ－ＩｇＧ阳性率为８６．９％，孕妇ＲＶ－ＩｇＭ阳性率为３．２％。有自发流产史妇女ＲＶ－ＩｇＧ滴度显著高于正常妇女（Ｐ＜０．０５），有异常孕产史妇女ＲＶ－ＩｇＧ滴度在四个季度间有显著变化（Ｐ＜０．００５）。提示风疹感染与自发流产关系密切。     

Comparison of a chemiluminescence immunoassay and an enzyme immunoassay for detection of IgM antibodies against measles,mumps, rubella,cytomegalovirus (CMV), Epstein Barr virus (EBV), and human herpes virus (HHV) -1 and -2 infections

PurposeOutbreaks of vaccine-preventable viral diseases have been increasingly reported globally over the past few years. The burden of congenital viral infections, their impact on physical and mental development and the resulting economic loss to the family and the community are also well known. IgM antibody detection has been convenient in the diagnosis of acute viral infections, particularly in settings with limited resources where molecular tests are not feasible.MethodsThis is a comparative study between a chemiluminescence immunoassay (Liaison, DiaSorin, Saluggia, Italy) and an enzyme linked immunosorbent assay (ELISA) (Euroimmun, Lubeck, Germany) for the detection of IgM antibody against measles, mumps, rubella, CMV, EBV and HHV-1 and -2 viruses using a total of 345 samples. Results are expressed as agreement using kappa statistics.ResultsIn this study, CLIA is perfectly comparable to ELISA for the detection of IgM antibodies against measles (0.86) and mumps (0.92) with a moderate agreement for rubella (0.52), CMV (0.57), EBV (0.50), and HHV-1 and -2 (0.47) assays. However, a PABAK (prevalence-adjusted bias-adjusted kappa) showed improved agreement for rubella (0.64), CMV (0.65), EBV (0.60), and HHV-1 and -2 (0.88) assays.ConclusionsIgM antibody assays (CLIA and ELISA) against measles and mumps virus can be comparably used depending on the laboratory setup, throughput and expertise.     

Long-Term Follow-Up of Antibody Titers Against Measles,Mumps, and Rubella in Recipients of Allogenic Hematopoietic Cell Transplantation

Outbreaks of viral infections, such as measles, are regularly observed and pose a serious threat to recipients of allogeneic hematopoietic cell transplantation (HCT). The questions of how long cellular and humoral protective host immunity persists, and whether donor immunity can be transferred has not been clarified. Here we present a retrospective analysis of humoral immunity—serial antibody titers against measles, mumps, and rubella—in 331 patients who underwent allogeneic HCT at our single center between 2002 and 2015. Associations between the loss of protective antibody levels and clinical patient characteristics and transplantation parameters were examined. In general, antibody protection against measles persisted longer, with 72% of patients maintaining sufficient titers at 5 years post-HCT even without revaccination, while at that time only 65% and 50% of patients had protective immunity against rubella and mumps, respectively. The great majority of donors were seropositive for all 3 viruses; however, it appeared that donor humoral immunity could not be transferred and had no impact on post-HCT serostatus. Rather, the most relevant factor for persistent protective antibody titers against measles and rubella was whether patients were born before the introduction of the respective vaccine and thus were immunized by the wild-type disease-inducing virus instead of the vaccine. Moreover, the presence of moderate and severe chronic graft-versus-host disease (GVHD) was associated with more rapid loss of immune protection. In contrast, underlying disease, intensity of the conditioning regimen, use of antithymocyte globulin, age, and graft source had no influence on antibody titers. Overall, our findings suggest that the majority of antibodies against measles, mumps, and rubella originate from residual host cells, whereas donor immune status appears to have no influence on antibody protection post-HCT.     

Nonfebrile Seizures after Mumps,Measles, Rubella,and Varicella-Zoster Virus Combination Vaccination with Detection of Measles Virus RNA in Serum,Throat, and Urine

We report the case of a child presenting with nonfebrile seizures 6 and 13 days after the first vaccination with a measles, mumps, rubella, and varicella (MMRV) combination vaccine. Measles virus RNA was detected in the patient''s serum, throat, and urine. Genotyping revealed the Schwarz vaccine virus strain.     

Prevalence of IgG anti-HAV in patients with chronic hepatitis B and in the general healthy population in Korea

Background/Aims

Few studies have investigated hepatitis A virus (HAV) seroepidemiology in Koreans with chronic liver disease (CLD). This study compared the prevalence of IgG anti-HAV between the general healthy population and patients with hepatitis B virus-related CLD (HBV-CLD), with the aim of identifying predictors of HAV prior exposure.

Methods

In total, 1,319 patients were recruited between June 2008 and April 2010. All patients were tested for IgG anti-HAV, hepatitis B surface antigen (HBsAg), and antibodies to hepatitis C virus. The patients were divided into the general healthy population group and the HBV-CLD group based on the presence of HBsAg. The seroprevalence of IgG anti-HAV was compared between these two groups.

Results

The age-standardized seroprevalence rates of IgG anti-HAV in the general healthy population and patients with HBV-CLD were 52.5% and 49.1%, respectively. The age-stratified IgG anti-HAV seroprevalence rates for ages ≤19, 20-29, 30-39, 40-49, 50-59, and ≥60 years were 14.3%, 11.2%, 45.5%, 90.5%, 97.6% and 98.3%, respectively, in the general healthy population, and 0%, 9.8%, 46.3%, 91.1%, 97.7%, and 100% in the HBV-CLD group. In multivariate analysis, age (<30 vs. 30-59 years: OR=19.339, 95% CI=12.504-29.911, P<0.001; <30 vs. ≥60 years: OR=1060.5, 95% CI=142.233-7907.964, P<0.001) and advanced status of HBV-CLD (OR=19.180, 95% CI=4.550-80.856, P<0.001) were independent predictors of HAV prior exposure.

Conclusions

The seroprevalence of IgG anti-HAV did not differ significantly between the general-healthy-population and HBV-CLD groups. An HAV vaccination strategy might be warranted in people younger than 35 years, especially in patients with HBV-CLD.     

Serial Short-Term Outcomes of Very-Low-Birth-Weight Infants in the Korean Neonatal Network From 2013 to 2020

BackgroundWe aimed to determine the current survival rate and short-term outcomes of very-low-birth-weight infants (VLBWIs) in Korea, as well as whether the survival rate and short-term outcomes have improved over time since 2013, which was when the Korean Neonatal Network (KNN) was launched.MethodsThis study used data from the annual reports of the KNN from 2013 to 2020. A total of 16,351 VLBWIs born at gestational age (GA) ≥ 22 weeks between January 1, 2013, and December 31, 2020, and who were registered in the KNN were enrolled. Serial outcomes were analyzed according to era (2013–14, 2015–16, 2017–18, and 2019–20).ResultsMore mothers delivered by cesarean section, had diabetes or hypertension during their pregnancy, and received antenatal steroids when analyzed by era. Fewer infants were intubated at birth and had air leaks when analyzed by era. The overall survival rate of VLBWIs between 2013 and 2020 was 87%. The rate of respiratory distress syndrome was 77% and that of bronchopulmonary dysplasia was 32% between 2013 and 2020. The rates of intraventricular hemorrhage (grade ≥ 3), periventricular leukomalacia, and sepsis decreased over time. The survival rate of infants with a GA of 26 weeks has improved serially according to era.ConclusionSince the launch of the KNN in 2013, the survival rates of infants with GA 26 weeks and short-term outcomes have improved, which implies a quality improvement in antenatal and delivery room care. Further studies on the long-term neurodevelopmental outcomes of these KNN registrants are warranted.     

Economic impact of switching rubella IgG methodologies to the prenatal public health program in Alberta

BackgroundDespite widespread use of a universal rubella standard, variability in rubella antibody titre can be observed between assays, particularly at the low end of the linear range.ObjectivesHere, we investigate the impact of a methodology change for rubella IgG from the Abbott AXSYM to the Abbott Architect in a comprehensive prenatal screening program in the Canadian province of Alberta.Study design51,815 specimens (21,399 tested by AxSYM and 30,416 tested by Architect) submitted for routine prenatal screening between January 2006 and December 2012 from women who lived in Alberta after the universal childhood immunization programme for rubella was implemented, and whose immunization records were available, were included in the study.ResultsPrenatal samples tested by AxSYM for rubella IgG were approximately 30% higher than those reported by Architect. Among individuals who had tests across multiple pregnancies, the change in test platform led to an additional 7% of women who initially tested positive, becoming non-positive (i.e. negative or indeterminate) in their subsequent tests. The tendency of the Architect IgG assay to report lower quantitative values was demonstrated across all birth cohorts and vaccination status, and resulted in an additional 2800 women requiring vaccination between 2010 and 2012 with an estimated cost of $38,500.ConclusionThe change in rubella IgG screening assay resulted in a significant increase in the number of women who required post partum vaccination and Public Health follow-up.     

Serial Long-Term Growth and Neurodevelopment of Very-Low-Birth-Weight Infants: 2022 Update on the Korean Neonatal Network

BackgroundWe aimed to evaluate the long-term growth and neurodevelopmental outcomes of very-low-birth-weight infants (VLBWIs, birth weight < 1,500 g) born between 2013, the establishment of the Korean Neonatal Network (KNN), and 2018, both at 18–24 months of corrected age and three years of age, using a nationwide large cohort, and to evaluate whether these outcomes have improved over time since 2013.MethodsThis study used data from the annual reports of the KNN for 18–24 months of corrected age (follow-up 1) and three years of age (follow-up 2). Follow-up 1 data were collected from 10,065 eligible VLBWIs born between January 1, 2013, and December 31, 2018. Follow-up 2 data were collected from 8,156 eligible VLBWIs born between January 1, 2013, and December 31, 2017.ResultsThe overall follow-up rates of VLBWIs at follow-ups 1 and 2 were 74.6% (7,512/10,065) and 57.7% (4,702/8,156), respectively. The overall mortality rate between discharge from the neonatal intensive care unit and follow-up 1 was 1% (104/10,065). The overall mortality rate between follow-ups 1 and 2 was 0.049% (4/8,156). Growth restrictions decreased over time, especially weight growth restrictions, which significantly decreased according to era (17% in infants born in 2013–2014 and 13% in infants born in 2017–2018). Fewer infants were re-hospitalized and required rehabilitative support according to era at follow-up 1. More infants had language developmental delays and required language support according to era, both at follow-ups 1 and 2. The incidence of cerebral palsy has significantly decreased over time, from 6% in infants born in 2013–2014 to 4% in infants born in 2017–2018 at follow-up 1, and from 8% in infants born in 2013–2014 to 5% in infants born in 2017 at follow-up 2.ConclusionLong-term outcomes of VLBWIs regarding weight growth and cerebral palsy, the most common motor disability in childhood, have improved serially according to era since 2013. However, the rate of infants with language delays requiring language support has increased according to era. Further studies are required on the increased trends of language delay and language support while improving motor outcomes.     

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

The goal of this study was to evaluate the BioPlex 2200 Toxoplasma, rubella, and cytomegalovirus (CMV) (ToRC) IgG and IgM multiplex immunoassays (Bio-Rad Laboratories, Hercules, CA) and compare the results to those of conventional testing by enzyme immunoassay (EIA) and enzyme-linked fluorescent assay (ELFA). Serum specimens (n = 600) submitted for routine ToRC IgG and IgM testing by EIA (SeraQuest, Doral, FL; Diamedix, Miami, FL) or ELFA (Vidas; bioMérieux, Durham, NC) were also tested by the BioPlex ToRC multiplex immunoassays. Samples showing discordant results were retested by both methods, with further discrepancies being arbitrated by a third assay. Following repeat testing, the BioPlex Toxoplasma, rubella, and CMV IgG assays demonstrated agreements of 98.7 (592/600 specimens), 93.3 (560/600 specimens), and 98.3% (590/600 specimens), respectively, while the ToRC IgM assays yielded agreements of 91.2 (547/600 specimens), 87.3 (524/600 specimens), and 95.2% (571/600 specimens), respectively. The BioPlex ToRC IgG assays provided results comparable to EIA/ELFA results, with kappa coefficients showing near-perfect agreement for the Toxoplasma (κ = 0.94) and CMV (κ = 0.97) IgG assays and substantial agreement for the rubella IgG assay (κ = 0.66). The BioPlex ToRC IgM assays showed lower specificity with only slight agreement for Toxoplasma IgM (κ = 0.07), poor agreement for rubella IgM (κ = −0.03), and moderate agreement for CMV IgM (κ = 0.55). Both the BioPlex IgG and IgM assays reduced turnaround time (1.7 h versus 5.5 h by EIA/ELFA for 100 specimens) and eliminated the necessity to manually pipette or aliquot specimens prior to testing.Congenital infections caused by Toxoplasma gondii, rubella, and cytomegalovirus (CMV) are a significant cause of neonatal mortality and childhood morbidity worldwide (6, 18, 21). Due to their nonspecific clinical manifestations and the importance of early recognition of in utero infection, serologic screening for these pathogens has been considered a routine practice in many parts of the world (11). Conventional methods for the detection of antibodies to Toxoplasma, rubella, and CMV (ToRC) include immunofluorescence (IFA), enzyme immunoassay (EIA), and enzyme-linked fluorescent assay (ELFA). These techniques have been used for years in both diagnostic and screening protocols for ToRC infection and have demonstrated reliable performance (5, 10, 14, 22). However, these methods have certain limitations, including low throughput, significant hands-on time, and in the case of IFA, a subjective interpretation of results.Recently, multiplex flow immunoassay (MFI) technology emerged as a novel approach to assess the serologic response to various infectious diseases (3, 4, 13). This technology is similar to traditional EIA but allows for the simultaneous detection and identification of multiple analytes in a single reaction. MFI technology uses a liquid suspension array of up to 100 unique microspheres (5- to 6-μm beads), each conjugated with a different capture molecule (e.g., antibody, antigen, nucleic acid). Each capture analyte is detected and quantitated following the addition of a fluorescently labeled reporter molecule (e.g., phycoerythrin) whose emission is measured by a flow-based detector. In 2009, Bio-Rad Laboratories (Hercules, CA) received FDA clearance for a ToRC IgG immunoassay based on MFI technology. In addition, Bio-Rad has developed a prototype ToRC IgM assay for use in cases of suspected acute infection. These assays are fully automated on the BioPlex 2200 automated analyzer (Bio-Rad Laboratories), allowing for a high-throughput analysis of the ToRC IgG and IgM class antibody response.Due to increasing test volumes (∼20% in the past 5 years) and the limitations of conventional methods (e.g., low throughput, increased hands-on time, and the requirement to aliquot samples prior to testing), we undertook a study to evaluate the BioPlex ToRC IgG and IgM immunoassays using clinical serum samples. The goal of this study was to compare the results of the BioPlex to routine testing by EIA/ELFA, using a third assay to arbitrate discordant results.