Evaluation of the Bio-Rad BioPlex 2200 syphilis multiplex flow immunoassay for the detection of IgM- and IgG-class antitreponemal antibodies

Development and Evaluation of an Enzyme-Linked Immunosorbent Assay Targeting Rabies-Specific IgM and IgG in Human Sera

Immunity from rabies depends on rabies virus neutralizing antibodies (RVNA) induced after immunization; however, the influence of antibody isotype switching has not been extensively investigated. This has become particularly relevant with changes in World Health Organization (WHO) recommended rabies vaccine regimens that may influence RVNA isotype kinetics, potentially affecting the peak, and longevity, of RVNA immunoglobulin (IgG) levels. We developed rapid and reliable assays for quantifying the anti-rabies IgM/IgG class switch in human serum based on an indirect ELISA technique. The immune response was tracked in ten individuals naïve to the rabies vaccine by quantifying serum titers weekly, from day seven to day 42 post-immunization, using a serum neutralization assay and the ELISA IgM/IgG assays. The average RVNA IU/mL levels were at D0 ≤ 0.1, D7 0.24, D14 8.36, D21 12.84, D28 25.74 and D42 28.68. Levels of specific IgM antibodies to rabies glycoprotein (EU/mL) were higher, on average, at D7, 1.37, and from D14, 5.49, to D21, 6.59. In contrast, average IgG antibodies (EU/mL) predominated from D28, 10.03, to D42, 14.45. We conclude that levels of anti-rabies IgM/IgG at D28 characterize the isotype class switch. These assays, combined with serum neutralization assays, distinguished the RVNA levels in terms of the IgM/IgG responses and are expected to add to the diagnostic repertoire, provide additional information in establishing rabies vaccine regimens, both post- and pre-exposure prophylaxis, and contribute to research efforts.

Development of a Bead-Based Multiplex Assay for Use in Multianalyte Screening and Surveillance of HIV, Viral Hepatitis, Syphilis, and Herpes

Diagnostic assays that can simultaneously determine the presence of infection with multiple pathogens are key for diagnosis and surveillance. Current multiplex diagnostic assays are complex and often have limited availability. We developed a simple, multianalyte, pathogen detection assay for screening and serosurveillance using the Luminex Magpix platform that is high throughput and can be helpful in monitoring multiple diseases. The Luminex bead-based 10-plex immunoassay for the detection of HIV-1, HIV-2, Treponema pallidum, hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus 1 (HSV-1), and HSV-2 infections was accomplished by coupling beads with specific antigens to detect IgG antibodies in plasma or serum samples. Each coupled antigen was systematically optimized, and the performance was evaluated using a panel of well-characterized specimens (n = 417) that contained antibodies to HIV-1, HIV-2, T. pallidum, HBV, HCV, HSV-1, and HSV-2. The multiplex assay had a sensitivity of 92.2% (95% Clopper-Pearson confidence interval [CI], 90.2 to 94.0%) and a specificity of 98.1% (95% CI, 97.6 to 98.7%). The sensitivities and specificities for disease-specific biomarker detection ranged from 68.7 to 100% and 95.6 to 100%, respectively. The results showed that the 10-plex immunoassay had an overall agreement of 96.7% (95% CI, 96.7 to 97.3%) with reference tests and a corresponding kappa value of 0.91 (95% CI, 0.90 to 0.93). Kappa values for the individual pathogens ranged from 0.69 to 1.00. The assay is robust and allows the simultaneous detection of antibodies to multiple antigens using a small sample volume in a high-throughput format. This assay has the potential to simplify disease surveillance by providing an alternative to expensive and highly specialized individual tests.

A Model for Syphilis Screening in the Emergency Department

The incidence of syphilis infections is on the rise, particularly among African American men and men who have sex with men, and it is reaching epidemic levels in these communities throughout the United States. Although syphilis is relatively inexpensive to treat and cure and is a predictor for HIV incidence among men and transgender women who have sex with men, rates of co-screening for syphilis are low in the emergency department setting, with a dearth of literature on this topic since the 1990s and early 2000s. In this case study, we describe an operational model for routine syphilis screening implemented in June 2017 at the University Hospitals Cleveland Medical Center in Cleveland, Ohio. We describe the advantages of screening using a reverse testing algorithm rather than the traditional method and the necessity of partnering with the Cleveland Department of Public Health for both diagnostic and follow-up logistics.

Performance of Treponema pallidum recombinant proteins in the serological diagnosis of syphilis

Syphilis serodiagnosis is challenging because distinct clinical forms of the infection may influence serological performance and discordant results between tests make clinical decisions difficult. Several recombinant Treponema pallidum-proteins have already been tested for syphilis diagnosis and they are critical to achieve high accuracy in serological testing. Our aim was to assess the varied from performance of T. pallidum-recombinant proteins TmpA, TpN17 and TpN47 for syphilis serodiagnosis. The proteins were evaluated using sera of 338 T. pallidum-negative, 173 T. pallidum-positive individuals and 209 sera from individuals infected with unrelated diseases. The diagnostic potential was validated by analysis of ROC curves. In the liquid microarray analyses, the ROC curve varied from 99.0% for TmpA and TpN17 to 100% for TpN47. The sensitivity score yielded values of up to 90% for TpN17, 100% for TpN47 and 80.0% for TmpA. The lowest and highest specificity values were presented by TpN47 (91.9%) and TmpA antigens (100%), respectively. TpN47 showed the highest accuracy score (95.5%) among all the recombinant proteins assayed. For the ELISA, the ROC curve was 97.2%, 91.8% and 81.6% for TpN17, TmpA and TpN47, respectively. TpN17 and TmpA yielded a sensitivity of 69.9%, while TpN47 obtained a value of 53.8%. Specificity was almost 100% for all three proteins. No cross-reaction was observed for TpN17 in the serum samples from non-bacterial infections. Regarding leptospirosis-positive samples, cross-reactivity score was varied from 8.6 to 34.6%. This is most probably due to conservation of the epitopes in these proteins across bacteria. The use of recombinant proteins in immunoassays for syphilis diagnosis was showed provide greater reliability to results of the treponemal assays. Despite the low sensitivity, the proteins showed high diagnostic capacity due to the AUC values found. However, an improvement in sensitivity could be achieved when antigenic mixtures are evaluated.

Clinical Performance of the BioPlex 2200 Syphilis Total & RPR Assay at a Tertiary Medical Center with a High Rate of Syphilis

Manual treponemal and nontreponemal serologic testing has historically been used for the diagnosis of syphilis. This approach is simple and reproducible but labor intensive. Recently, the FDA cleared the fully automated BioPlex 2200 Syphilis Total & RPR assay for the detection of treponemal and nontreponemal antibodies. We evaluated the clinical performance of this assay at a tertiary medical center with a high syphilis prevalence. Prospective consecutively collected (n = 400) and known RPR-positive (n = 100) specimens were compared using predicate manual rapid plasma reagin (RPR) and fluorescent treponemal antibody absorption (FTA) methods and the BioPlex 2200 Syphilis Total & RPR assay. Positive and negative percent agreements (PPA and NPA, respectively) between the assays were calculated. The PPA and NPA between the manual and BioPlex 2200 RPR results for the prospective population were 85% (17/20; 95% confidence interval [CI], 69% to 100%) and 98% (373/380; 95% CI, 97% to 99%), respectively. The PPA for the manual RPR-positive population was 88% (88/100; 95% CI, 82% to 94%). Overall, the manual and BioPlex 2200 RPR titers demonstrated 78% (99/127) concordance within ±1 dilution and 94% (120/127) within ±2 dilutions. An interpretation of the syphilis serologic profile using the traditional algorithm showed a concordance of 99.5% in the prospective population and 85% in the manual RPR-positive cohort. The performance of the BioPlex 2200 Syphilis Total & RPR assay is comparable to those of manual methods. The high NPA of this assay combined with the ability to automate a historically labor-intensive assay is an appealing attribute for syphilis screening in a high-volume laboratory.

Use of Treponemal Screening Assay Strength of Signal to Avoid Unnecessary Confirmatory Testing

BACKGROUND

Our reverse syphilis testing algorithm consists of a treponemal IgG multiplex flow immunoassay (MFI) followed by both rapid plasma reagin titer and the Treponema pallidum particle agglutination (TPPA) test on specimens with a reactive MFI result. We report here the impact of a modified reverse algorithm, in which the strength of signal of the MFI is used to avoid unnecessary TPPA testing.

METHODS

The Bioplex syphilis IgG MFI was used as the syphilis screening assay, and specimens with equivocal (antibody index 0.9 or 1.0), or reactive (antibody index ≥ 1.1) results were further tested by rapid plasma reagin titer and TPPA test. We performed a retrospective, descriptive analysis of all specimens received for syphilis screening between January and May of 2014. A cost analysis was performed, taking into account labor and reagent expenses.

RESULTS

In our diverse patient population consisting of high-risk incarcerated persons, low-risk obstetrical/gynecological patients and high-risk miscellaneous clinic and inpatients, 430 (65%) of 665 MFI-positive specimens had antibody indices of 8 or greater. Greater than 99% of these specimens were reactive by the TPPA test. Avoiding TPPA testing of specimens with an MFI antibody index ≥8 would save over US $4800 annually in laboratory costs.

CONCLUSIONS

The TPPA testing is unnecessary on specimens with MFI antibody indices ≥8. This would substantially reduce the TPPA testing volume and also reduce laboratory expenses.

Syphilis

Treponema pallidum subspecies pallidum (T. pallidum) causes syphilis via sexual exposure or via vertical transmission during pregnancy. T. pallidum is renowned for its invasiveness and immune-evasiveness; its clinical manifestations result from local inflammatory responses to replicating spirochaetes and often imitate those of other diseases. The spirochaete has a long latent period during which individuals have no signs or symptoms but can remain infectious. Despite the availability of simple diagnostic tests and the effectiveness of treatment with a single dose of long-acting penicillin, syphilis is re-emerging as a global public health problem, particularly among men who have sex with men (MSM) in high-income and middle-income countries. Syphilis also causes several hundred thousand stillbirths and neonatal deaths every year in developing nations. Although several low-income countries have achieved WHO targets for the elimination of congenital syphilis, an alarming increase in the prevalence of syphilis in HIV-infected MSM serves as a strong reminder of the tenacity of T. pallidum as a pathogen. Strong advocacy and community involvement are needed to ensure that syphilis is given a high priority on the global health agenda. More investment is needed in research on the interaction between HIV and syphilis in MSM as well as into improved diagnostics, a better test of cure, intensified public health measures and, ultimately, a vaccine.

Evaluation of the Lumipulse G TP-N Chemiluminescent Immunoassay as a Syphilis Screening Test

A syphilis diagnosis is often aided by the detection of treponemal and nontreponemal antibodies. Automated treponemal antibody detection systems enable high-volume clinical laboratories to perform syphilis screening at a faster pace with lower labor costs. The Lumipulse G TP-N chemiluminescent immunoassay is an automated system that qualitatively detects IgG and IgM antibodies against Treponema pallidum antigens in human serum and plasma. To assess performance characteristics and workflow efficiency, the Lumipulse G TP-N assay was compared to the Bioplex 2200 Syphilis IgG multiplex flow immunoassay. Among the 4,134 routine and HIV samples tested by the two automated assays, the percentage of agreement was excellent at 99.0% (95% confidence interval [CI], 98.6% to 99.2%; κ, 0.89), with the Lumipulse G TP-N having a shorter time to first and subsequent results. All specimens with reactive syphilis screening results were further tested by rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TP·PA) testing (n = 231). The results from the RPR-reactive samples (n = 82) showed complete concordance with the two automated assays, while the TP·PA assay displayed some discrepancies. The positive percent agreement (PPA) and negative percent agreement (NPA) between the TP·PA test and the Lumipulse G TP-N test were 98.9% and 77.3%, respectively. The Bioplex 2200 Syphilis IgG immunoassay displayed a similar PPA (100%) but a substantially lower NPA (15.9%). Patient chart reviews of discrepant results suggested that the Lumipulse G TP-N assay produced 27 fewer falsely reactive results and can reduce the amount of additional confirmatory RPR and TP·PA testing needed. The analogous performance characteristics of the two automated systems indicate that the Lumipulse G TP-N assay is suitable for high-throughput syphilis screening.

Development, Characterisation and Application of Monoclonal Antibodies for the Detection and Quantification of Infectious Salmon Anaemia Virus in Plasma Samples Using Luminex Bead Array Technology

Infectious salmon anaemia virus (ISAV) is an orthomyxovirus that has had a significant economic impact on Atlantic salmon farming in Europe, North America and Chile. Monoclonal antibodies (mAbs) were developed against Segment 3 (encoding the viral nucleoprotein, NP) of the virus. Six of the mAbs were shown to be specific to ISAV and recognised all isolates from Scotland, Norway and Canada. They reacted with ISAV in enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody technique (IFAT) and western blotting. They were also used to develop a novel detection method based on Luminex (Bio-Plex) bead-based flow cytometric technology for the detection of ISAV in the plasma of Atlantic salmon (Salmo salar L.) smolts experimentally infected with ISAV. Fish were challenged by intraperitoneal (i.p.) injection of virus at 50% Tissue Culture Infective Dose (TCID50) = 2.8 x106 per animal. Virus present in plasma of infected fish, collected at 0, 4, 8, 12, 16, 21 and 28 days post infection using a non-lethal sampling method (n = 12 at each time point), was quantified using the optimised Bio-Plex assay. The results obtained with this assay were compared with absolute quantification of the virus by RT-qPCR using SYBR Green I and TaqMan chemistries. The Bio-Plex assay developed using the NP mAbs appears to be a rapid, sensitive method for detecting and quantifying ISAV in small volumes of fish plasma and has the potential to be multiplexed for the detection of other fish pathogens (e.g. during co-infections). To our knowledge this is the first report of the use of Luminex (Bio-Plex) technology for the detection of a fish pathogen.

Evaluation of Multiplex-Based Antibody Testing for Use in Large-Scale Surveillance for Yaws: a Comparative Study

WHO has targeted yaws for global eradication by 2020. The program goals are to interrupt the transmission in countries where yaws is endemic and to certify countries as yaws free where yaws was endemic in the past. No new rapid plasmin reagin (RPR) seroreactivity in young children is required for certification of elimination at a country level. We sought to evaluate whether antibody responses to specific treponemal antigens measured in a high-throughput multiplex bead array (MBA) assay differentiate past versus current infection and whether a nontreponemal lipoidal antigen test can be incorporated into the MBA. Serum and dried blood spot specimens collected for yaws surveillance projects in Ghana, Vanuatu, and Papua New Guinea (PNG) were run on MBA to measure antibodies against recombinant p17 (rp17) and treponemal membrane protein A (TmpA) treponemal antigens. Results were compared to standard treponemal laboratory (TPPA or TPHA [TPP(H)A]) and quantitative RPR test data. Of 589 specimens, 241 were TPP(H)A⁺/RPR⁺, 88 were TPP(H)A⁺/RPR⁻, 6 were TPP(H)A⁻/RPR⁺, and 254 were negative for both tests. Compared to TPP(H)A, reactive concordance of rp17 was 93.7%, while reactive concordance of TmpA was only 81.9%. TmpA-specific reactivity showed good correlation with RPR titers (R² = 0.41; P < 0.0001). IgG responses to the lipoidal antigen used in RPR testing (cardiolipin) were not detected in the MBA. Our results suggest that TmpA can be used as a treponemal antigen marker for recent or active infection and potentially replace RPR in a high-throughput multiplex tool for large-scale yaws surveillance.

Cross-reactivity between Lyme and syphilis screening assays: Lyme disease does not cause false-positive syphilis screens

Increased rates of Lyme disease and syphilis in the same geographic area prompted an assessment of screening test cross-reactivity. This study supports the previously described cross-reactivity of Lyme screening among syphilis-positive sera and reports evidence against the possibility of false-positive syphilis screening tests resulting from previous Borrelia burgdorferi infection.

ELISA in the multiplex era: potentials and pitfalls

Multiplex immunoassays confer several advantages over widely adopted singleplex immunoassays including increased efficiency at a reduced expense, greater output per sample volume ratios and higher throughput predicating more resolute, detailed diagnostics and facilitating personalised medicine. Nonetheless, to date, relatively few protein multiplex immunoassays have been validated for in vitro diagnostics in clinical/point-of-care settings. This review article will outline the challenges, which must be ameliorated prior to the widespread integration of multiplex immunoassays in clinical settings: (i) biomarker validation; (ii) standardisation of immunoassay design and quality control (calibration and quantification); (iii) availability, stability, specificity and cross-reactivity of reagents; (iv) assay automation and the use of validated algorithms for transformation of raw data into diagnostic results. A compendium of multiplex immunoassays applicable to in vitro diagnostics and a summary of the diagnostic products currently available commercially are included, along with an analysis of the relative states of development for each format (namely planar slide based, suspension and planar/microtitre plate based) with respect to the aforementioned issues.

Recent trends in the serologic diagnosis of syphilis

Complexities in the diagnosis of syphilis continue to challenge clinicians. While direct tests (e.g., microscopy or PCR) are helpful in early syphilis, the mainstay of diagnosis remains serologic tests. The traditional algorithm using a nontreponemal test (NTT) followed by a treponemal test (TT) remains the standard in many parts of the world. More recently, the ability to automate the TT has led to the increasingly widespread use of reverse algorithms using treponemal enzyme immunoassays (EIAs). Rapid, point-of-care TTs are in widespread use in developing countries because of low cost, ease of use, and reasonable performance. However, none of the current diagnostic algorithms are able to distinguish current from previously treated infections. In addition, the reversal of traditional syphilis algorithms has led to uncertainty in the clinical management of patients. The interpretation of syphilis tests is further complicated by the lack of a reliable gold standard for syphilis diagnostics, and the newer tests can result in false-positive reactions similar to those seen with older tests. Little progress has been made in the area of serologic diagnostics for congenital syphilis, which requires assessment of maternal treatment and serologic response as well as clinical and laboratory investigation of the neonate for appropriate management. The diagnosis of neurosyphilis continues to require the collection of cerebrospinal fluid for a combination of NTT and TT, and, while newer treponemal EIAs look promising, more studies are needed to confirm their utility. This article reviews current tests and discusses current controversies in syphilis diagnosis, with a focus on serologic tests.

Canadian Public Health Laboratory Network laboratory guidelines for the use of serological tests (excluding point-of-care tests) for the diagnosis of syphilis in Canada

Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted as well as spread from an infected mother to her fetus or through blood transfusions. The laboratory diagnosis of syphilis infection is complex. Because this organism cannot be cultured, serology is used as the principal diagnostic method. Some of the issues related to serological diagnoses are that antibodies take time to appear after infection, and serology screening tests require several secondary confirmatory tests that can produce complex results needing interpretation by experts in the field. Traditionally, syphilis screening was performed using either rapid plasma reagin or Venereal Disease Research Laboratory tests, and confirmed by treponemal tests such as MHA-TP, TPPA or FTA-Abs. Currently, that trend is reversed, ie, most of the laboratories in Canada now screen for syphilis using treponemal enzyme immunoassays and confirm the status of infection using rapid plasma reagin or Venereal Disease Research Laboratory tests; this approach is often referred to as the reverse algorithm. This chapter reviews guidelines for specimen types and sample collection, treponemal and non-treponemal tests utilized in Canada, the current status of serological tests for syphilis in Canada, the complexity of serological diagnosis of syphilis infection and serological testing algorithms. Both traditional and reverse sequence algorithms are recommended and the algorithm used should be based on a combination of local disease epidemiology, test volumes, performance of the proposed assays and available resources.

Performance of the BioPlex 2200 flow immunoassay in critical cases of serodiagnosis of toxoplasmosis

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.

The endemic treponematoses

The agents of human treponematoses include four closely related members of the genus Treponema: three subspecies of Treponema pallidum plus Treponema carateum. T. pallidum subsp. pallidum causes venereal syphilis, while T. pallidum subsp. pertenue, T. pallidum subsp. endemicum, and T. carateum are the agents of the endemic treponematoses yaws, bejel (or endemic syphilis), and pinta, respectively. All human treponematoses share remarkable similarities in pathogenesis and clinical manifestations, consistent with the high genetic and antigenic relatedness of their etiological agents. Distinctive features have been identified in terms of age of acquisition, most common mode of transmission, and capacity for invasion of the central nervous system and fetus, although the accuracy of these purported differences is debated among investigators and no biological basis for these differences has been identified to date. In 2012, the World Health Organization (WHO) officially set a goal for yaws eradication by 2020. This challenging but potentially feasible endeavor is favored by the adoption of oral azithromycin for mass treatment and the currently focused distribution of yaws and endemic treponematoses and has revived global interest in these fascinating diseases and their causative agents.

Determination of class M and G antibodies to T.pallidum antigens in patients with primary syphilis

The authors present the results of a study of blood serum samples obtained from patients with clinically diagnosed primary syphilis by the linear immunoblotting method to determine IgM and IgG antibodies to T. pallidum antigens, which enabled the authors to study the intensity of the humoral immune response to individual T. pallidum antigens at early stages of the infection. The humoral response by means of the synthesis of specific class M antibodies in case of primary syphilis was accompanied by the formation of Class G antibodies in most cases; the frequency of revealing Class M and G antibodies was as follows: TmpA antigen 100 and 98.68%; TpN47 90.79 and 97.37%; TpN17 90.79 and 89.47%; TpN 15 72.37 and 73.69% of all cases, respectively; the content of class G antibodies to each of the four T. pallidum antigens exceeded the levels of Class M antibodies by more than twice. Different profiles of the humoral immune response with the involvement of IgM and IgG antibodies distinguished by a more expressed synthesis of antibodies to any or several of T. pallidum antigens were discovered and characterized for the first time. The clinical sensitivity of the IgM immunoblotting method for diagnosing primary syphilis amounted to 85.53%, IgG immunoblotting 92.11%, which means that the method can be used to diagnose early forms of syphilis.

Evaluation of the BioPlex 2200 syphilis system as a first-line method of reverse-sequence screening for syphilis diagnosis

Despite recent technological advances, the diagnosis of syphilis remains a challenging enterprise. Actually, most high-volume laboratories have adopted the "reverse algorithm" due several factors, including the potential to automate testing. Recently, immunoassays processed on random-access systems have been proposed as screening tests. The purpose of this study was to evaluate diagnostic performances of BioPlex 2200 Syphilis IgG and BioPlex 2200 Syphilis IgM, tests based on Multiplex Flow technology, in comparison with the performance of Architect Syphilis TP, a chemiluminescent immunoassay for the detection of IgG and/or IgM anti-Treponema pallidum antibodies. A retrospective study was performed with a panel of 100 blood donor sera, a panel of 350 clinical and laboratory-characterized syphilitic sera, and 170 samples obtained from subjects with potentially interfering conditions. Moreover, 200 unselected samples submitted to the Microbiology Laboratory of St. Orsola Hospital in Bologna for routine screening for syphilis were evaluated. As confirmatory tests, T. pallidum hemagglutination and Western blot assays were used. Considering the IgG Western blot (WB) assay to be the gold standard method, BioPlex 2200 Syphilis IgG specificity was far higher than Architect Syphilis TP specificity (89.7% versus 78.4%, respectively), whereas the sensitivity was 100% for both automated methods. Compared to the IgM WB assay, BioPlex 2200 Syphilis IgM performed with a specificity of 94.9%, whereas the sensitivity was 84.8%. Considering the excellent ease of use and automation, the high sample throughput and its valuable analytical performances, BioPlex Syphilis 2200 IgG could represent a suitable choice for high-volume laboratories. BioPlex Syphilis 2200 IgM could be considered a good addition to IgG testing for uncovering active infections.

Methods for the determination of M class anti-T. pallidum antibodies for early diagnostics of syphilis

The review covers issues related to the present-day administration of laboratory blood test methods for the determination of specific Class M immunoglobulins against antigens of the syphilis pathogen, T. pallidum (immune-enzyme assay, immunofluorescence reaction, linear immunoblotting). Indications and diagnostic features of the aforesaid medical methods for early diagnostics of acquired or congenital syphilis were determined; cases of reinfection were verified and the intensity of the infection was assessed in the patients who had previously received specific treatment. The article provides recommendations for using specific IgM determination methods described in present-day Russian and foreign guides and standards of syphilis diagnostics.

The laboratory diagnostics of syphilis: yesterday, today, tomorrow

The article covers issues related to the development of laboratory methods used for the diagnostic of syphilitic infection in the historical aspect as well as for the nearest and remote future. Priorities of the application of several diagnostic methods have been highlighted depending on the stage and form of syphilis, on the performed specific treatment and the contingent of examined patients. The authors give recommendations for its use reflected in modern Russian and foreign manuals and standards of syphilis diagnostics. Laboratory methods such as immunochemiluminescence assay, хМАР-technology and aspects of their clinical application are specially highlighted. The authors provide data on applied methods of molecular typing of Т. pallidum and detection of genetic determinants of the resistance of the syphilis pathogen to antimicrobial substances.

Which algorithm should be used to screen for syphilis?

PURPOSE OF REVIEW

A growing number of laboratories have implemented a reverse screening algorithm for syphilis testing, which has created confusion among many healthcare providers. This review focuses on recent data addressing the clinical and economical impact of reverse screening and discusses the advantages and limitations of the traditional and contemporary algorithms.

RECENT FINDINGS

Screening for syphilis using a treponemal assay detects a higher number of patients with reactive results compared to traditional screening by rapid plasma reagin (RPR). Furthermore, a significant percentage of patients who are reactive by a treponemal screening assay are nonreactive by RPR. These discordant results may occur in patients with past, treated or untreated syphilis; early syphilis; or no syphilis. Recent reports suggest that the reverse screening algorithm may result in increased patient follow-ups, overtreatment, and potentially higher cost. However, other data suggest that reverse screening facilitates the detection of latent and early syphilis, while offering an objective and automated screening approach.

SUMMARY

The Centers for Disease Control and Prevention currently recommends syphilis screening with a nontreponemal test. However, as laboratories continue to implement the reverse screening algorithm, it is important that samples with discordant screen-reactive, RPR-nonreactive results be tested by a second treponemal assay to assist in the interpretation of results.

Multiplexed quantification of 63 proteins in human urine by multiple reaction monitoring-based mass spectrometry for discovery of potential bladder cancer biomarkers

Three common urological diseases are bladder cancer, urinary tract infection, and hematuria. Seventeen bladder cancer biomarkers were previously discovered using iTRAQ - these findings were verified by MRM-MS in this current study. Urine samples from 156 patients with hernia (n=57, control), bladder cancer (n=76), or urinary tract infection/hematuria (n=23) were collected and subjected to multiplexed LC-MRM/MS to determine the concentrations of 63 proteins that are normally considered to be plasma proteins, but which include proteins found in our earlier iTRAQ study. Sixty-five stable isotope-labeled standard proteotypic peptides were used as internal standards for 63 targeted proteins. Twelve proteins showed higher concentrations in the bladder cancer group than in the hernia and the urinary tract infection/hematuria groups, and thus represent potential urinary biomarkers for detection of bladder cancer. Prothrombin had the highest AUC (0.796), with 71.1% sensitivity and 75.0% specificity for differentiating bladder cancer (n=76) from non-cancerous (n=80) patients. The multiplexed MRM-MS data was used to generate a six-peptide marker panel. This six-peptide panel (afamin, adiponectin, complement C4 gamma chain, apolipoprotein A-II precursor, ceruloplasmin, and prothrombin) can discriminate bladder cancer subjects from non-cancerous subjects with an AUC of 0.814, with a 76.3% positive predictive value, and a 77.5% negative predictive value. This article is part of a Special Section entitled: Understanding genome regulation and genetic diversity by mass spectrometry.

Direct comparison of the traditional and reverse syphilis screening algorithms in a population with a low prevalence of syphilis

We describe the first direct comparison of the reverse and traditional syphilis screening algorithms in a population with a low prevalence of syphilis. Among 1,000 patients tested, the results for 6 patients were falsely reactive by reverse screening, compared to none by traditional testing. However, reverse screening identified 2 patients with possible latent syphilis that were not detected by rapid plasma reagin (RPR).

Modern approaches and prospects of development of laboratory diagnostics for sexuallytransmitted infections

The authors provide a comparison of modern approaches to the use of well-known laboratory methods for diagnostics of syphilis, gonorrhea, trichomoniasis and urogenital clamidiosis, which are approved in the world science and practice. They also examine promising directions in the development of up-to-date laboratory technologies (biomicrochips, multiprimer PCR, mass spectrometry, PLEX-ID technology, immunoblotting, chemiluminescence immunoassay (CLIA), xMAP, pyrosequencing) for detecting STD pathogens, which is necessary to make an etiological diagnosis and determine efficient methods of treatment minimizing the period of time required for examination of patients.

Role of transgenic plants in agriculture and biopharming

At present, environmental degradation and the consistently growing population are two main problems on the planet earth. Fulfilling the needs of this growing population is quite difficult from the limited arable land available on the globe. Although there are legal, social and political barriers to the utilization of biotechnology, advances in this field have substantially improved agriculture and human life to a great extent. One of the vital tools of biotechnology is genetic engineering (GE) which is used to modify plants, animals and microorganisms according to desired needs. In fact, genetic engineering facilitates the transfer of desired characteristics into other plants which is not possible through conventional plant breeding. A variety of crops have been engineered for enhanced resistance to a multitude of stresses such as herbicides, insecticides, viruses and a combination of biotic and abiotic stresses in different crops including rice, mustard, maize, potato, tomato, etc. Apart from the use of GE in agriculture, it is being extensively employed to modify the plants for enhanced production of vaccines, hormones, etc. Vaccines against certain diseases are certainly available in the market, but most of them are very costly. Developing countries cannot afford the disease control through such cost-intensive vaccines. Alternatively, efforts are being made to produce edible vaccines which are cheap and have many advantages over the commercialized vaccines. Transgenic plants generated for this purpose are capable of expressing recombinant proteins including viral and bacterial antigens and antibodies. Common food plants like banana, tomato, rice, carrot, etc. have been used to produce vaccines against certain diseases like hepatitis B, cholera, HIV, etc. Thus, the up- and down-regulation of desired genes which are used for the modification of plants have a marked role in the improvement of genetic crops. In this review, we have comprehensively discussed the role of genetic engineering in generating transgenic lines/cultivars of different crops with improved nutrient quality, biofuel production, enhanced production of vaccines and antibodies, increased resistance against insects, herbicides, diseases and abiotic stresses as well as the safety measures for their commercialization.

Identification of false-positive syphilis antibody results using a semiquantitative algorithm

Screening patients for syphilis serology using a "treponemal assay-first" approach presents unique challenges, particularly when applied to low-prevalence populations. The use of a screening algorithm that incorporates semiquantitative values from treponemal antibody test results can help to identify potential false-positive results while requiring a minimum of repeat testing.

Treponema-specific tests for serodiagnosis of syphilis: comparative evaluation of seven assays

The diagnosis of syphilis is challenging and often relies on serologic tests to detect treponemal or nontreponemal antibodies. Recently, the Centers for Disease Control and Prevention and the Association of Public Health Laboratories proposed an update to the syphilis serology testing algorithm, in which serum samples are first tested using a treponema-specific test and positive samples are analyzed with a nontreponemal assay. The goal of this study was to compare the performance of seven treponemal assays (BioPlex 2200 syphilis IgG [Bio-Rad, Hercules, CA], fluorescent treponemal antibody [FTA] assay [Zeus Scientific, Raritan, NJ], Treponema pallidum particle agglutination [TP-PA; Fujirebio Diagnostics, Malvern, PA], Trep-Sure enzyme immunoassay [EIA; Phoenix Biotech, Oakville, Ontario, Canada], Trep-Chek EIA [Phoenix Biotech], Trep-ID EIA [Phoenix Biotech], and Treponema ViraBlot IgG [Viramed Biotech AG, Planegg, Germany]) using serum samples (n = 303) submitted to our reference laboratory. In addition to testing with these 7 assays, all samples were tested by a rapid plasma reagin (RPR) assay and a treponemal IgM Western blot assay (Viramed ViraBlot). Compared to the FTA assay as the gold standard, the evaluated treponemal tests demonstrated comparable levels of performance, with percent agreement ranging from 95.4% (95% confidence interval, 92.3 to 97.3) for the Trep-Sure EIA to 98.4% (96.1 to 99.4) for the Trep-ID EIA. Compared to a "consensus of the test panel" (defined as at least 4 of 7 treponemal tests being in agreement), the percent agreement ranged from 95.7% (92.7 to 97.5) for Trep-Sure to 99.3% (97.5 to 99.9) for Trep-ID. These data may assist clinical laboratories that are considering implementing a treponemal test for screening or confirmatory purposes.

Major directions in the development of diagnostics technologies indermatovenerology

This review describes major directions in the development of laboratory diagnostics of STDs and dermatoses in the Russian Federation. It also discusses strategic directions in the development of diagnostics departments in dermatovenerological institutions (three-level structure of laboratory aid, centralization, automation, standardization of tests, external and internal laboratory quality control, introduction of laboratory information technologies and laboratory information exchange systems). It also substantiates the priority directions in the diagnostics of STDs (etiological diagnostics, acceleration of the cycle of laboratory tests for patients, determination of the resistance of causative agents to antimicrobial drugs, molecular monitoring of the spreading of STDs) and dermatoses (diagnosis verification, diagnosing an organ pathology, marker diagnostics, prevention and prediction of the efficacy and safety of dermatosis treatment).

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.