Peptide Enzyme-linked Immunosorbent Assay Research Articles

Prediction, Synthesis and Evaluation of a Synthetic Peptide as an Enzyme-Linked Immunosorbent Assay (ELISA) Candidate for Screening of Bovine Antibodies against Theileria annulata.

Tick-borne diseases (TBDs) of livestock are endemic across various parts of tropical countries. Theileriosis is one such economically important TBD, caused by the Theileriidae family of organisms, which is transmitted by ticks. Theileria annulata, the causative agent of tropical theileriosis, contributes a significant loss to the dairy sector by causing anorexia, high fever, anemia, inflammatory changes in vital organs and icterus, thus, a loss in milk yield. Though vaccines are available, their protective efficacy is not absolute, and treatment is limited to early diagnosis of the causative agent. Routinely, microscopic identification of piroplasms in the erythrocytes (Giemsa-stained) of infected animals or schizonts in lymph node biopsies are practiced for diagnosis. PCR-based techniques (multiplex, uniplex, nested and real-time) have been reported to perform well in diagnosing active infection. Several attempts have been made using serological assays like Dot blot, ELISA and ICT, but the results were of variable sensitivity and specificity. Recombinant proteins like the Theileria annulata merozoite surface antigen (Tams1) and Theileria annulata surface protein (TaSP) have been explored as antigenic candidates for these assays. In the present study, we predicted an immunogenic peptide, i.e., TaSP-34, from the TaSP using various computational tools. The predicted peptide was custom synthesized. The diagnostic potential of the peptide was assessed by indirect plate ELISA to detect the bovine-IgM against Theileria annulata. Alongside, a recombinant truncated TaSP (rTaSP(tr)) was expressed and purified, which was used to compare the performance of the peptide as a diagnostic candidate. The IgM-based peptide ELISA was 100% sensitive and 92.77% specific as compared to PCR (Tams1 targeting), while 98.04% sensitivity and 97.44% specificity were observed in comparison with rTaSP(tr) ELISA. Almost perfect agreement between peptide ELISA and Tams1 PCR was observed with a Cohen's kappa coefficient (κ-value) of 0.901 and agreement of 95.31%. Further, the κ-value between the peptide ELISA and rTaSP(tr) ELISA was found to be 0.95, and the agreement was 97.65%, which shows a good correlation between the two tests. The findings suggest that the TaSP-34 peptide can be an efficient and new-generation diagnostic candidate for the diagnosis of T. annulata. Furthermore, the peptide can be synthesized commercially at a larger scale and can be a cost-effective alternative for the protein-based diagnostic candidates for T. annulata.

Passively Acquired Constant Region 5-Specific Antibodies Associated With Improved Survival in Infants Who Acquire Human Immunodeficiency Virus.

Studying vertical human immunodeficiency virus (HIV) transmission enables the impact of passively transferred antibodies on HIV transmission and pathogenesis to be examined. Using phage display of HIV envelope peptides and peptide enzyme-linked immunosorbent assay (ELISA), we found that, in infants who acquired HIV, passive antibody responses to constant region 5 (C5) were associated with improved survival in 2 cohorts. In a combined analysis, C5 peptide ELISA activity was correlated directly with survival and estimated infection time and inversely with set point viral load. These results suggest that preexisting C5-specific antibodies may be correlated with the survival of infants living with HIV, motivating additional research into their protective potential.

Antibody Response to HML-2 May Be Protective in Amyotrophic Lateral Sclerosis.

Reactivation of HERV-K(HML-2) has been found in subsets of individuals with amyotrophic lateral sclerosis (ALS). This study examines the antibody response against HML-2 in ALS and analyzes its clinical relevance. Antibodies to HML-2 envelope (env) were analyzed using a peptide array for epitope mapping and by a peptide enzyme-linked immunosorbent assay (ELISA) in 242 healthy donors, and 243 ALS and 85 multiple sclerosis (MS) individuals. Extracellular levels of HML-2 were analyzed by digital polymerase chain reaction (PCR). Antibodies in the sera of ALS individuals recognized more HML-2 env peptides compared to healthy controls (p < 0.0001). ALS individuals had higher levels of HML-2 than healthy donors (p=0.02) and higher antibody levels against a select HML-2 env peptide compared to healthy donors or individuals with multiple sclerosis (p < 0.0001). 55.14% of ALS compared to 21.16% of healthy donors and 13.10% of MS individuals had antibodies against the HML-2 peptide (AUC=0.769, p < 0.0001). Levels of extracellular HML-2 DNA in serum (p=0.02) and the number of HML-2 env peptides recognized by ALS sera (p=0.02) correlated with disease duration. Among ALS individuals, lower levels of HML-2 antibodies were associated with a definite diagnosis per EL Escorial criteria (p=0.03), and with a lower predicted (p=0.02) and observed survival (p=0.03). There is a differential antibody response against specific epitopes of HML-2 env in ALS and controls, suggesting epitope spreading, likely due to persistent antigenic exposure following reactivation of the viral genes. Low levels of antibodies to HML-2 env in ALS are associated with poor prognosis and decreased survival probability. ANN NEUROL 2022;92:782-792.

Novel Synthetic Peptide-based Enzyme Linked Immunosorbent Assay for Antibody Detection in Viral Infections of the Central Nervous System

Introduction: Viral infections of Central Nervous System (CNS) are associated with severe neurological sequelae and can lead to significant morbidity if not adequately diagnosed and treated. An immunological assay detecting antibodies in the Cerebrospinal Fluid (CSF) of the patients is widely used for diagnosis of viral infections of the CNS. In the present study, diagnostic efficacy of in-house designed synthetic peptide based Enzyme Linked Immunosorbent Assay (ELISA) was evaluated for detection of antibodies against neurotropic viruses panel such as Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Varicella Zoster Virus (VZV), Japanese Encephalitis Virus (JEV), Dengue (DENV), West Nile Virus (WNV) and Chandipura Virus (CHPV) in CSF of suspected cases. Aim: To determine the diagnostic efficacy of in-house developed synthetic peptide-based ELISA in viral infections of the CNS. Materials and Methods: A retrospective study was conducted in Central India Institute of Medical Science, Nagpur, Maharashtra, India. The suspected case of CNS viral infections of the patients were enrolled in this study from January 2013 to December 2015. Total 150 suspected cases of viral CNS infections and 135 control cases were recruited. Total 32 synthetic peptides of highly immunogenic proteins of respective seven neurotropic viruses were designed and synthesised. The designed peptides were evaluated in CSF samples of both the viral CNS infections and control cases for detection of Imunoglobulin G (IgG) and IgM antibodies using in-house developed antibody detection method. The developed tests were further compared with commercially available antibody detection ELISA kit. The sensitivity and specificity of peptide-ELISA were determined by Receiver Operating Curve (ROC) analysis and p-value was calculated by comparison of means by t-test. Results: Out of total 150 cases of CNS viral infections, a total of 31 CSF samples including 15 for CMV and 16 of JEV were positive by in-house peptide ELISA. The synthetic peptides STGDVVDISP, KQKSLVEL, RTLEVFKE, RSSNVED of CMV and ITYECPK, RRSVSVQT, GESSLVN of JEV showed a significant difference in mean absorbance value for IgM and IgG antibodies in CSF of suspected cases of viral CNS infection. Conclusion: The results demonstrated that the synthetic peptide-based ELISA is rapid, cost-effective, simple and efficient immunodiagnostic assay for initial screening of viral CNS infection.

POS0441 DEVELOPMENT OF RHEUMATOID ARTHRITIS AMONG ANTI-CITRULLINATED PROTEIN ANTIBODIES POSITIVE ASYMPTOMATIC INDIVIDUALS: A PROSPECTIVE OBSERVATIONAL STUDY

Background:In the idividuals with genetic and enviromental risk factors, immune events at mucosal surfaces occur and may precede systemic autoimmunity. Anti-citrullinated protein antibodies (ACPA) are present in the serum for an average of 3-5 years prior to the onset of rheumatoid arthritis (RA) during an asymptomatic period. In ACPA-positivite individuals, the additional presence of RA-related risk factors appears to add significant power for the development of RA. To date, there have been few reports in which clinical courses of ACPA-positive asymptomatic individuals were investigated prospectively.Objectives:To observe the clinical time course of ACPA-positive healthy population for the development of RA.Methods:Healthy volunteers without joint pain or stiffness, who attended the comprehensive health screening of our hospital, were enrolled in this prospective observational study. The serum ACPA levels were quantified by Ig-G anti-cyclic citrullinated peptide enzyme-linked immunosorbent assay with levels &gt; 4.4 U/mL considered positive. ACPA-positive subjects were followed by rheumatologists of our department clinically or a questionnaire sent by mail for screening to detect arthritis.Results:5,971 healthy individuals without joint symptons were included. Ninty-two (1.5%) were positive for ACPA. Of these, 19 (20.7%) developed RA and two were suspected as RA by mail questionnaire. Their average age were 58-years, and women were 68%. The average duration between the date of serum sampling and diagnosis was 10.7 months. ACPA-positive individuals who developed to RA had higher serum ACPA and Ig-M rheumatoid factor levels than ACPA-positive individuals who did not (P value by Mann-Whitney U test: 0.002, 0.005, respectively).Conclusion:Among ACPA-positive asymptomatic individuals, 20% developed RA. The higher titer of ACPA and Ig-M rheumatoid factor levels are risk factors for devoloping RA.Disclosure of Interests:None declared

Anti-Cytosolic 5'-Nucleotidase 1A Autoantibodies Are Absent in Juvenile Dermatomyositis.

ObjectiveTo assess anti–cytosolic 5′‐nucleotidase 1A (anti–cN‐1A) autoantibodies in children with juvenile dermatomyositis (DM) and healthy controls, using 3 different methods of antibody detection, as well as verification of the results in an independent cohort.MethodsAnti–cN‐1A reactivity was assessed in 34 Dutch juvenile DM patients and 20 healthy juvenile controls using the following methods: a commercially available full‐length cN‐1A enzyme‐linked immunosorbent assay (ELISA), a synthetic peptide ELISA, and immunoblotting with a lysate from cN‐1A–expressing HEK 293 cells. Sera from juvenile DM patients with active disease and those with disease in remission were analyzed. An independent British cohort of 110 juvenile DM patients and 43 healthy juvenile controls was assessed using an in‐house full‐length cN‐1A ELISA.ResultsAnti–cN‐1A reactivity was not present in sera from juvenile DM patients or healthy controls when tested with the commercially available full‐length cN‐1A ELISA or by immunoblotting, in either active disease or disease in remission. Additionally, in the British juvenile DM cohort, anti–cN‐1A reactivity was not detected. Three Dutch juvenile DM patients had weakly positive results for 1 of 3 synthetic cN‐1A peptides measured by ELISA.ConclusionJuvenile DM patients and young healthy individuals did not show anti–cN‐1A reactivity as assessed by different antibody detection techniques.

Peptide enzyme\u2010linked immunosorbent assay (pELISA) as a possible alternative to the neutralization test for evaluating the immune response to IBV vaccine

BackgroundInfectious bronchitis virus (IBV), a coronavirus, is one of the most important poultry pathogens worldwide due to its multiple serotypes and poor cross-protection. Vaccination plays a vital role in controlling the disease. The efficacy of vaccination in chicken flocks can be evaluated by detecting neutralizing antibodies with the neutralization test. However there are no simple and rapid methods for detecting the neutralizing antibodies.ResultsIn this study, a peptide enzyme-linked immunosorbent assay (pELISA) as a possible alternative to the neutralization test for evaluating the immune response to IBV vaccine was developed. The pELISA could indirect evaluate neutralizing antibody titers against different types of IBV in all tested sera. The titers measured with the pELISA had a coefficient of 0.83 for neutralizing antibody titers.ConclusionsThe pELISA could detect antibodies against different types of IBV in all tested sera. The pELISA has the potential to evaluate samples for IBV-specific neutralizing antibodies and surveillance the infection of IBV.

Serological Responses to Toxoplasma gondii and Matrix Antigen 1 Predict the Risk of Subsequent Toxoplasmic Encephalitis in People Living With Human Immunodeficiency Virus (HIV).

Clinically useful predictors for fatal toxoplasmosis are lacking. We investigated the value of serological assays for antibodies to whole Toxoplasma antigens and to peptide antigens of the Toxoplasma cyst matrix antigen 1 (MAG1), for predicting incident toxoplasmic encephalitis (TE) in people living with human immunodeficiency virus (HIV; PLWH). We performed a nested case control study, conducted within the Multicenter AIDS Cohort Study (MACS), using serum samples obtained 2 years prior to diagnosis of TE from 28 cases, and 37 HIV disease-matched Toxoplasma seropositive controls at matched time-points. Sera were tested for Toxoplasma antibodies using a commercial assay and for antibodies to MAG1_4.2 and MAG1_5.2 peptides in enzyme-linked immunosorbent assay (ELISA). Two years prior to clinical diagnosis, 68% of TE cases were MAG1_4.2 seropositive compared with 16% of controls (odds ratio [OR] 25.0, 95% confidence interval [CI] 3.14-199.18). Corresponding results for MAG1_5.2 seropositivity were 36% and 14% (OR 3.6, 95% CI .95-13.42). Higher levels of antibody to MAG1_4.2 (OR 18.5 per doubling of the optical density [OD] value, 95% CI 1.41-242) and to Toxoplasma (OR 2.91 for each OD unit increase, 95% CI 1.48-5.72) were also associated with the risk of TE. When seropositivity was defined as the presence of MAG1 antibody or relatively high levels of Toxoplasma antibody, the sensitivity was 89% and specificity was 68% for subsequent TE. Antibodies to MAG1 showed predictive value on the occurrence of TE in PLWH, and the predictive performance was further improved by adding the levels of Toxoplasma antibody. These measures could be clinically useful for predicting subsequent diseases in multiple at-risk populations.

Major vault protein/lung resistance related protein: a novel biomarker for rheumatoid arthritis.

Rheumatoid arthritis (RA) can lead to joint destruction and early institution of effective treatment can preserve joint function. Biomarkers can establish early diagnosis and predict effect of treatment. Vault particles, large cytoplasmic ribonucleoprotein particles that participate in inflammation, might serve as biomarkers. The aim of this study was to assess the diagnostic and the prognostic value of major vault protein (MVP) and their antibodies in RA. Serum samples from 159 RA patients, 26 early RA (ERA) patients, 21 patients with osteoarthritis (OA) and 30 healthy individuals were tested for MVP, anti-cyclic citrullinated peptide (anti-CCP) and C-reactive protein (CRP) using enzyme-linked immunosorbent assays (ELISA). Rheumatoid factor (RF) was tested by nephelometry, and anti-MVP antibodies were detected by anti-MVP peptide ELISA using an in-house protocol. MVP levels were higher in RA and ERA, compared to OA and healthy controls (p<0.00001). A combination of MVP with RF or anti-CCP showed an improved diagnostic accuracy compared to RF or anti-CCP alone in RA and ERA. MVP exhibited similar AUC levels to anti-CCP and RF in RA whereas in ERA, MVP exhibited the same or slightly higher AUC levels, compared to anti-CCP and RF, respectively. High MVP levels were associated with lack of response to treatment. Levels of anti-MVP peptide 2 antibodies were significantly higher in RA compared to healthy controls (t= 2.73, p=0.007). MVP and autoantibodies against MVP may have the potential to serve as diagnostic and prognostic biomarkers in RA.

Identification of continuous immunoglobulin G epitopes of Dermatophagoides farinae allergens by peptide microarray immunoassay.

Dermatophagoides farinae, as a common house dust mite species, is one of the main sources of allergens in the world. At present, Dermatophagoides farinae is found to contain more than 30 groups of allergens. These allergens are used for allergen-specific immunotherapy (AIT) of allergic diseases. During the AIT process, immunoglobulin G (IgG) antibodies can block immunoglobulin E (IgE) antibody-induced allergic reactions in the human body. One of the mechanisms may be that IgG and IgE competitively bind to the same allergic protein, so it is necessary to explore the binding sites (epitopes) of IgG antibodies to allergens. In this study, peptide arrays were constructed to react with the serums from patients with allergic asthma to find the IgG epitopes of several allergens including major allergens (Der f 1, 2) and mid-tier allergens (Der f 4, 5, and 7), and then verified by enzyme-linked immunosorbent assay (ELISA) test. Relevant epitopic sequences were located on the tertiary structure of individual allergens, as reconstructed by homology modeling. One IgG epitope of Der f 1 (90-106aa, NVPSELDLRSLRTVTPI), five IgG epitopes of Der f 4 (61-77aa, ERYQPVSYDIHTRSGDE; 193-209aa, FRSDASTHQWPDDLRSI; 226-242aa, HPFIYHETIYYGGNGIN; 271-287aa, LRWLRNFGTEWGLVPSG; 352-368aa, NDWVGPPTDQHGNILSV), and one IgG epitope of Der f 5 (84-101aa, RYNVEIALKSNEILERDL) were identified. IgG epitopes of Der f 2, 7 were not found. There are overlaps between the IgG and IgE epitopes of Der f 1, 4, and 5. These findings not only reflect the practicality of peptide array and ELISA test in the allergen IgG epitope identification, but also provide more information for further understanding of the human immunological changes during AIT and the molecular mechanisms of IgG blocking IgE activity.

Antibody Response to the Furin Cleavable Twenty-Seven Amino Acid Peptide (p27) of the Fusion Protein in Respiratory Syncytial Virus (RSV) Infected Adult Hematopoietic Cell Transplant (HCT) Recipients.

Background: Cleavage of the inactive precursor fusion protein (F0) of respiratory syncytial virus (RSV) at two furin-recognition sites is required for membrane fusion activity, and the cleavage releases the twenty-seven amino acid peptide (p27). However, a recent study shows that p27 was an immunodominant epitope in RSV infected children, indicating that p27 was recognized as an immunogen. In the present study, we investigated the immunogenicity of p27 in an immunocompromised population of adults by measuring serum and mucosal antibody responses to p27 in samples from adult hematopoietic cell transplant (HCT) recipients. Methods: We prospectively enrolled a cohort of RSV infected HCT recipients. Serum and nasal-wash samples were obtained within the first week of RSV infection (acute) and 3 to 5 weeks post-infection (convalescent). We quantified the serum and mucosal IgG and IgA anti-p27 antibodies by a RSV/A p27 peptide enzyme-linked immunosorbent assay (ELISA) and serum and mucosal p27 like antibodies (P27LA) by a p27 competitive antibody (P27CA) assay. Results: The lower limit of detection for the ELISA and P27CA assays was 0.2 and 50 ng/mL, respectively with no cross-reaction detected with a panel of monoclonal antibodies targeting pre-fusion and post-fusion antigenic sites. P27 antibodies were detected at nanogram concentration in sera and nasal washes in the majority of RSV infected HCT recipients. However, there was no significant difference in the geometric mean antibody concentrations between the acute and convalescent sera (except for serum P27LA), between HCT recipients who shed RSV <14 days and ≥14 days, as well as between RSV/A and RSV/B infected HCT recipients. In addition, approximately 30% of HCT recipients had a 4-fold or greater decrease in mucosal IgG and IgA anti-p27 antibodies during viral clearance. Conclusion: In conclusion, in RSV naturally infected adult HCT recipients, the antibodies against p27 were detectable in both serum and nasal wash samples with higher concentration in serum than that in nasal washes. However, nearly 30% of RSV infected HCT recipients had a significant decrease in their mucosal anti-p27 antibody, suggesting that IgG and IgA anti-p27 antibodies were binding to either free viruses or RSV infected cells containing p27, and that anti-p27 antibodies in the respiratory tract were part of the mucosal antibody response in controlling RSV infection.

Screening and Identification of Linear B Cell Epitopes Within the Nonstructural Proteins of Enterovirus 71.

Enterovirus 71 (EV-A71) has attracted widespread attention in the past decade because of its higher neurotropicity in addition to causing hand-foot-and-mouth disease (HFMD). Mapping epitopes of viral proteins may promote our understanding of antiviral humoral immunity, and is useful for clinical application. In this study, the linear B cell epitopes within nonstructural proteins of EV-A71 were identified using bioinformatics methods combined with peptide enzyme-linked immunosorbent assay (ELISA). Twenty epitopes were predicted and located at 2ABC (7), 3ABC (5), and 3D (8) protein, respectively. Of 20 epitope-containing peptides, 14 were verified by ELISA (S/CO >2.1), 9 of which had higher reactivity (S/CO >5.0). Furthermore, synthetic peptide SP09 (EV-A71-3ABC26-41) can react with healthy children sera, and its immunoreactivity was closest to that of EV-A71-VP1 protein. The protein BLAST analysis revealed that SP09 may contain a common epitope due to the high homology of amino acid sequences with other members of human Enterovirus species A. These findings may be useful in the development serological tests for the diagnosis of HFMD caused by a broad range of human Enterovirus species A.

Comprehensive Molecular Serology of HumanChlamydia trachomatisInfections by Peptide Enzyme-Linked Immunosorbent Assays

Sensitive species-specific detection of anti-Chlamydia trachomatis antibodies is compromised by cross-reactivity of the C.trachomatis antigens used in standard microimmunofluorescence (MIF) testing and enzyme-linked immunosorbent assays (ELISAs). Previously, we discovered 48 strongly reactive C.trachomatis-specific B cell epitope peptides from 21 immunodominant proteins. Here we comprehensively evaluated the 11 top-ranked C.trachomatis-specific peptide antigens from 8 proteins for use in C.trachomatis serology. Sera from 125 women with nucleic acid amplification test (NAAT)-confirmed active C.trachomatis infection and from 49 healthy women with a low risk of C.trachomatis infection were used as anti-C.trachomatis antibody-positive and -negative sera. Results obtained for detection of IgG1, IgG3, and IgA1 antibodies against the 11 C.trachomatis peptide antigens were compared to results from 4 commercial anti-C.trachomatis IgG ELISAs. Using composite reference standards (CRS) of all assays for anti-C.trachomatis antibody status, commercial ELISAs detected antibodies in antibody-positive women with sensitivities of 51.5% to 64.8%. In contrast, a combination of the results of all 11 peptides detected IgG (IgG1 and IgG3) antibodies with 91.8% sensitivity, and a labor-saving combination of the 5 optimal peptides still detected antibodies in antibody-positive women with 86.5% sensitivity (all at 98% specificity). The superior performance of the combined peptide ELISAs was confirmed by area under the receiver operating characteristic curve (ROC-AUC), likelihood ratio, and predictive value analyses. The higher sensitivity of the peptide assays results from using multiple B cell epitopes of several C.trachomatis immunodominant proteins, including OmpA, compared to exclusively using the OmpA antigens used in commercial ELISAs. Thus, ELISAs with combined use of synthetic peptide antigens for C.trachomatis antibody detection have the advantage of simultaneous high sensitivity and high specificity.IMPORTANCE For detection of anti-Chlamydia trachomatis antibodies by serological assays, use of classical whole-organism chlamydial antigens results in high cross-reactivity. These antigens bind mainly antibodies against the major outer membrane protein (OmpA) and bind antibodies against other immunodominant non-OmpA proteins to a lesser extent, resulting in poor assay sensitivity. The specificity of C.trachomatis serology is also compromised by the high prevalence of cross-reactive anti-C.pneumoniae antibodies in human populations. We previously identified 48 highly specific C.trachomatis B cell epitope peptide antigens of 21 immunodominant proteins. This study validated peptide antigen-based novel ELISAs that provide highly specific and sensitive detection of anti-C.trachomatis antibodies. Compared to four commercial ELISAs that achieved only poor sensitivities (51.5% to 64.8%), the combined signals of 5 to 11 peptides provided high sensitivity (86.5% to 91.8%) at the same 98% specificity. Thus, by using multiple peptide antigens of immunodominant proteins, we created simple ELISAs with specificity and sensitivity superior to standard C. trachomatis serodiagnosis.

Evaluation of the Diagnostic Performance of Onchocerca volvulus Linear Epitopes in a Peptide Enzyme-Linked Immunosorbent Assay.

.Diagnostic tools for the detection of infection with Onchocerca volvulus are presently limited to microfilaria detection in skin biopsies and serological assessment using the Ov16 immunoglobulin G4 (IgG4) rapid test, both of which have limited sensitivity. We have investigated the diagnostic performance of a peptide enzyme-linked immunosorbent assay (ELISA) based on immunodominant linear epitopes previously discovered. Peptides that were used in these assays were designated O. volvulus motif peptides (OvMP): OvMP-1 (VSV-EPVTTQET-VSV), OvMP-2 (VSV-KDGEDK-VSV), OvMP-3 (VSV-QTSNLD-VSV), and the combination of the latter two, OvMP-23 (VSV-KDGEDK-VSV-QTSNLD-VSV). Sensitivity (O. volvulus infection), specificity (non-helminth infections), and cross-reactivity (helminth infections) were determined using several panels of clinical plasma isolates. OvMP-1 was found to be very sensitive (100%) and specific (98.7%), but showed substantial cross-reactivity with other helminths. Of the other peptides, OvMP-23 was the most promising peptide with a sensitivity of 92.7%, a specificity of 100%, and a cross-reactivity of 6%. It was also demonstrated that these peptides were immunoreactive to IgG but not IgG4, and there is no correlation with the Ov16 IgG4 status, making them promising candidates to complement this already available test. Combination of the Ov16 IgG4 rapid test and OvMP-23 peptide ELISA led to a sensitivity of 97.3% for the detection of O. volvulus infection, without compromising specificity and with minimal impact on cross-reactivity. The available results open the opportunity for a “clinical utility use case” discussion for improved O. volvulus epidemiological mapping.

Identification of Immunoreactive Peptides of Toxins to Simultaneously Assess the Neutralization Potency of Antivenoms against Neurotoxicity and Cytotoxicity of Naja atra Venom.

Assessing the neutralization capability of nonlethal but medically relevant toxins in venom has been a challenging task. Nowadays, neutralization efficacy is evaluated based simply on the survival rates of animals injected with antivenom together with a predefined dose of venom, which can determine potency against neurotoxicity but not validate the capability to neutralize cytotoxin-induced complications. In this study, a high correlation with in-vivo and in-vitro neutralization assays was established using the immunoreactive peptides identified from short-chain neurotoxin and cytotoxin A3. These peptides contain conserved residues associated with toxin activities and a competition assay indicated that these peptides could specifically block the antibody binding to toxin and affect the neutralization potency of antivenom. Moreover, the titers of peptide-specific antibody in antivenoms or mouse antisera were determined by enzyme-linked immunosorbent assay (ELISA) simultaneously, and the results indicated that Taiwanese bivalent antivenom (BAV) and Vietnamese snake antivenom-Naja (SAV-Naja) exhibited superior neutralization potency against the lethal effect of short-chain neurotoxin (sNTX) and cytotoxicity of cardiotoxin/cytotoxin (CTX), respectively. Thus, the reported peptide ELISA shows not only its potential for antivenom prequalification use, but also its capability of justifying the cross-neutralization potency of antivenoms against Naja atra venom toxicity.

Seroreactivity to the C6 Peptide in Borrelia miyamotoi Infections Occurring in the Northeastern United States.

There are no US Food and Drug Administration (FDA)-approved diagnostic tests for Borrelia miyamotoi infection, an emerging tick-borne illness in the United States. The purpose of this study was to evaluate whether the FDA-approved C6 peptide enzyme-linked immunosorbent assay (ELISA) currently used to diagnose Lyme disease may potentially serve as a diagnostic test for B. miyamotoi infections. Serum specimens from 30 patients from the northeastern United States with B. miyamotoi infection established by a polymerase chain reaction assay of a blood specimen were tested using the C6 ELISA. To reduce confounding with Borrelia burgdorferi coinfection, 6 sera were excluded: 3 from patients with a positive Western immunoblot for antibodies to B. burgdorferi and 3 from patients for whom immunoblot testing had not been performed. Twenty-two of 24 (91.7% [95% confidence interval, 73.0%-98.8%]) evaluable B. miyamotoi patients were C6 ELISA reactive, principally on a convalescent-phase serum specimen. C6 ELISA index values were often well above the positive cutoff value of 1.1, exceeding 4 in 11 of the 22 (50.0%) C6 ELISA-reactive patients. Although previously regarded as a highly specific test for Lyme disease, the C6 ELISA is also regularly reactive on convalescent-phase serum samples of patients from the northeastern United States with B. miyamotoi infection.

Human seroprevalence of Borrelia miyamotoi in Manitoba, Canada, in 2011-2014: a cross-sectional study.

Hard tick-borne relapsing fever caused by Borrelia miyamotoi has been reported in Russia, the Netherlands, Germany, Japan and the northeastern and upper midwestern United States. We sought to investigate the presence of B. miyamotoi infection in humans in Manitoba, Canada. Two hundred fifty sera collected from residents of Manitoba with suspected Lyme disease between 2011 and 2014 were tested for Borrelia burgdorferi antibody using a C6 peptide enzyme-linked immunosorbent assay (ELISA) followed by Western blot. Residual sera were then anonymized, stored at -80°C and subsequently thawed and tested for B. miyamotoi antibody using a 2-step glycerosphosphodiester phosphodiesterase-based ELISA and Western blot assay. Twenty-four of the 250 (9.6%) sera tested positive for B. miyamotoi immunoglobulin G. Participants who were B. miyamotoi seropositive were predominantly male (54%) and younger on average than those who were seronegative (32 and 44 yr of age, respectively). Participants who were seropositive for B. burgdorferi were significantly more likely to be B. miyamotoi seropositive than those who were B. burgdorferi seronegative (20.3% v. 6.6%, respectively, odds ratio 3.6, 95% confidence interval 1.5-8.5). This initial report of human B. miyamotoi infection in Canada should raise awareness of hard tick-borne relapsing fever among clinicians and residents of areas in Canada and western North America where Lyme disease is endemic.

Update to: Application of Bayesian decision-making to laboratory testing for Lyme disease and comparison with testing for HIV.

In this study, Bayes' theorem was used to determine the probability of a patient having Lyme disease (LD), given a positive test result obtained using commercial test kits in clinically diagnosed patients. In addition, an algorithm was developed to extend the theorem to the two-tier test methodology. Using a disease prevalence of 5%-75% in samples sent for testing by clinicians, evaluated with a C6 peptide enzyme-linked immunosorbent assay (ELISA), the probability of infection given a positive test ranged from 26.4% when the disease was present in 5% of referrals to 95.3% when disease was present in 75%. When applied in the case of a C6 ELISA followed by a Western blot, the algorithm developed for the two-tier test demonstrated an improvement with the probability of disease given a positive test ranging between 67.2% and 96.6%. Using an algorithm to determine false-positive results, the C6 ELISA generated 73.6% false positives with 5% prevalence and 4.7% false positives with 75% prevalence. Corresponding data for a group of test kits used to diagnose HIV generated false-positive rates from 5.4% down to 0.1% indicating that the LD tests produce up to 46 times more false positives. False-negative test results can also influence patient treatment and outcomes. The probability of a false-negative test for LD with a single test for early-stage disease was high at 66.8%, increasing to 74.9% for two-tier testing. With the least sensitive HIV test used in the two-stage test, the false-negative rate was 1.3%, indicating that the LD test generates ~60 times as many false-negative results. For late-stage LD, the two-tier test generated 16.7% false negatives compared with 0.095% false negatives generated by a two-step HIV test, which is over a 170-fold difference. Using clinically representative LD test sensitivities, the two-tier test generated over 500 times more false-negative results than two-stage HIV testing.

Microbial Transglutaminase Used in Bread Preparation at Standard Bakery Concentrations Does Not Increase Immunodetectable Amounts of Deamidated Gliadin

The effect of standard bakery concentrations of microbial transglutaminase (MTG) in wheat bread preparation on the immunoreactivity of sera of celiac disease (CD) patients was investigated. Immunoblotting using monoclonal antibodies specific to unmodified and/or deamidated gliadin showed no differences between control bread and MTG bread. Deamidation of gliadin could not be detected at standard MTG concentrations. Sera of CD patients were characterized using anti-gliadin and anti-deamidated gliadin peptide (DGP) enzyme-linked immunosorbent assay and grouped into DGP high- and low-titer pools. The recognition pattern obtained after using both CD sera pools for immunoblotting did not reveal differences between control and MTG-treated bread protein extracts. Our results indicate that MTG treatment of wheat bread prepared with typical MTG concentrations used in standard bakery processes does not lead to immunodetectable amounts of CD immunotoxic deamidated gliadins.

High‐Titer Rheumatoid Arthritis Antibodies Preferentially Bind Fibrinogen Citrullinated by Peptidylarginine Deiminase 4

Most patients with rheumatoid arthritis (RA) harbor antibodies to citrullinated autoantigens such as citrullinated fibrinogen. Two isoforms of peptidylarginine deiminase (PAD), PAD type 2 (PAD2) and PAD4, which catalyze citrullination with different substrate specificities, can be detected in the synovium of RA patients. This study was undertaken to determine whether RA antibodies preferentially bind PAD2- or PAD4-citrullinated fibrinogen. RA patient and normal donor plasma specimens were tested for binding to PAD2- or PAD4-citrullinated fibrinogen, native fibrinogen, or citrullinated fibrinogen peptides in various dilutions by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Bands corresponding to masses demonstrating RA antibody reactivity by Western blotting were excised and analyzed by mass spectrometry. At low antibody titers (1:40 and 1:100), there was no significant difference between RA antibody reactivity to PAD2- and PAD4-citrullinated fibrinogen. When plasma was further diluted to 1:250 and 1:1,000, RA patient plasma bound PAD4-citrullinated fibrinogen significantly more than PAD2-citrullinated fibrinogen, as measured by ELISA and Western blotting. An increased antibody titer was associated with increased avidity for both PAD2- and PAD4-citrullinated fibrinogen. Both enzymes hypercitrullinated fibrinogen, but PAD4 citrullinated arginines more intermittently, generating a mix of citrullinated and noncitrullinated arginines. Peptide ELISA and preadsorption assays confirmed that the region of intermittent citrullination accounts for the majority of RA antibody binding to the β-chain of citrullinated fibrinogen. At high titers, RA antibodies preferentially bind fibrinogen modified by PAD4, because intermittent citrullination offers a more diverse assortment of citrullinated epitopes.