Aquaporin-4 Autoantibody Detection by ELISA: A Retrospective Characterization of a Commonly Used Assay

Objective. Aquaporin-4 (AQP4) serum autoantibodies are detected by a variety of methods. The highest sensitivity is achieved with cell-based assays, but the enzyme-linked immunosorbent assay (ELISA) is still commonly utilized by clinicians worldwide. Methods. We performed a retrospective review to identify all patients at the University of Utah who had AQP4 ELISA testing at ARUP Laboratories from 2010 to 2017. We then reviewed their diagnostic evaluation and final diagnosis based on the ELISA titer result. Results. A total of 750 tests for the AQP4 ELISA were analyzed, and 47 unique patients with positive titers were identified. Less than half of these patients (49%) met the clinical criteria for neuromyelitis optica spectrum disorder (NMOSD). In cases of low positive titers (3.0–7.9 U/mL, n = 19 ), the most common final diagnosis was multiple sclerosis (52.6%). In the moderate positive cohort (8.0–79.9 U/mL, n = 14 ), only a little more than half the cohort (64.3%) had NMOSD. In cases with high positives (80–160 U/mL, n = 14 ), 100% of patients met clinical criteria for NMOSD. Conclusions. Our data illustrates diagnostic uncertainty associated with the AQP4 ELISA, an assay that is still commonly ordered by clinicians despite the availability of more sensitive and specific tests to detect AQP4 autoantibodies in patients suspected of having NMOSD. In particular, low positive titer AQP4 ELISA results are particularly nonspecific for the diagnosis of NMOSD. The importance of accessibility to both sensitive and specific AQP4 testing cannot be overemphasized in clinical practice.

Latticed Gold Nanoparticle Conjugation via Monomeric Streptavidin in Lateral Flow Assay for Detection of Autoantibody to Interferon-Gamma

Adult-onset immunodeficiency syndrome (AOID) patients with autoantibodies (autoAbs) against interferon-gamma (IFN-γ) generally suffer from recurrent and recalcitrant disseminated non-tuberculous mycobacterial diseases. Since the early stages of AOID do not present specific symptoms, diagnosis and treatment of the condition are not practical. A simplified diagnostic method for differentiating AOID from other immunodeficiencies, such as HIV infection, was created. Anti-IFN-γ is generally identified using enzyme-linked immunosorbent assay (ELISA), which involves an instrument and a cumbersome process. Recombinant IFN-γ indirectly conjugated to colloidal gold was used in the modified immunochromatographic (IC) strips. The biotinylated-IFN-γ was incorporated with colloidal-gold-labeled 6HIS-maltose binding protein-monomeric streptavidin (6HISMBP-mSA) and absorbed at the conjugate pad. The efficacy of the IC strip upon applying an anti-IFN-γ autoAb cut-off ELISA titer of 2500, the sensitivity and specificity were 84% and 90.24%, respectively. When a cut-off ELISA titer of 500 was applied, the sensitivity and specificity were 73.52% and 100%, respectively.

28. Immunogenicity of rVSVΔG-ZEBOV-GP Ebola Vaccine (ERVEBO™) in Participants by Age, Sex, and Baseline GP-ELISA Titer: A Post Hoc Analysis of Three Phase 2/3 Trials

Background The recent Ebola virus disease (EVD) outbreak in the Democratic Republic of the Congo highlights the sustained threat of EVD morbidity and mortality where healthcare and vaccine delivery are challenging. ERVEBO®, a live recombinant vesicular stomatitis virus (VSV) vaccine containing the Zaire ebolavirus glycoprotein (GP) in place of the VSV GP (rVSVΔG-ZEBOV-GP), was developed by Merck & Co., Inc., Kenilworth, NJ, USA in collaboration with multiple partners to prevent EVD and has been approved for human use in several countries. Methods We pooled data from three Phase 2/3 clinical trials conducted in Guinea (FLW), Sierra Leone (STRIVE), and Liberia (PREVAIL) during the 2013–2016 West African outbreak to assess immune responses using a validated assay in each of the three studies and performed a post hoc analysis by sex, age (18–50 yrs & >50 yrs) and baseline (BL) GP-enzyme-linked immunosorbent assay (ELISA) titer (< 200 & ≥200 EU/ml). The full analysis set (FAS) population included the primary immunogenicity populations (all vaccinated participants with serology data collected within an acceptable day range) from all three trials. The endpoints were total IgG antibody response (EU/mL) measured by the GP-ELISA and neutralizing antibody response measured by the plaque reduction neutralization test (PRNT) to rVSVΔG-ZEBOV-GP at Days 14, 28, 180, and 365 postvaccination. Results In the overall population and in all subgroups, GP-ELISA and PRNT geometric mean titers increased from BL, with most peaking at Day 28 and persisting through Day 365. There were differences between males and females and between participants with BL GP-ELISA < 200 & ≥200 EU/ml. There did not appear to be a difference between age groups. Conclusion These data demonstrate that rVSVΔG-ZEBOV-GP elicits a robust and durable immune response up to 12 months in participants regardless of age, sex, or BL GP-ELISA titer. The higher immune responses observed in females and participants with preexisting immunity are consistent with those described in published literature for other vaccines. Disclosures Jakub Simon, MD, MS, Merck Sharp & Dohme Corp, a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Stephen Kennedy, MD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Scientific Research Study Investigator) Barbara Mahon, MD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Sheri Dubey, MS, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Rebecca Grant-Klein, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Ken Liu, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Jonathan Hartzel, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Beth-Ann Coller, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Carolee Welebob, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Mary Hanson, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Employee, Shareholder) Rebecca Grais, PhD, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA (Scientific Research Study Investigator)

Antibody Response to Feline Calicivirus Vaccination in Healthy Adult Cats

This study evaluated the prevalence of feline calicivirus (FCV) antibodies and response to vaccination in healthy adult cats. Cats >1 year (n = 111) that had not been vaccinated within 12 months of enrollment in the study received a vaccine containing inactivated FCV antigen strains 431 and G1. Antibodies were determined on Days 0, 7, and 28 by virus neutralization (VN) using FCV isolate KS20, and by broad spectrum blocking FCV enzyme-linked immunosorbent assay (ELISA). Factors associated with the presence of antibodies and vaccine response were determined by uni- and multivariate analysis. Pre-vaccination antibodies were detected in 62.2% of cats (CI95%: 52.9–70.1) by VN and in 77.2% (CI95%: 67.5–84.6) by ELISA. A ≥4-fold titer increase after vaccination was observed in 13.6% (CI95%: 8.3–21.4) of cats with VN and 33.7% (CI95%: 24.5–44.5) with ELISA. Factors associated with the presence of pre-vaccination VN antibodies were age (≥2 years; OR: 7.091; p = 0.022) and lack of previous vaccination (OR: 3.472; p = 0.014). The presence of pre-vaccination ELISA antibodies was associated with time since last vaccination (OR: 5.672; p = 0.043). Outdoor cats were more likely to have a ≥4-fold ELISA titer increase (OR: 5.556; p = 0.005). Many cats had pre-vaccination FCV antibodies, and their presence depended on previous vaccinations and increases with age. A ≥4-fold titer increase was rarely observed and was influenced by the lifestyle of the cat.

High Titer and Avidity of Nonneutralizing Antibodies against Influenza Vaccine Antigen Are Associated with Severe Influenza

ABSTRACTThe importance of neutralizing antibody in protection against influenza virus is well established, but the role of the early antibody response during the initial stage of infection in affecting the severity of disease is unknown. The 2009 influenza pandemic provided a unique opportunity for study because most patients lacked preexisting neutralizing antibody. In this study, we compared the antibody responses of 52 patients with severe or mild disease, using sera collected at admission. A microneutralization (MN) assay was used to detect neutralizing antibody. We also developed an enzyme-linked immunosorbent assay (ELISA) which detects both neutralizing and nonneutralizing antibodies against viral antigens from a split-virion inactivated monovalent influenza virus vaccine. While the MN titers were not significantly different between the two groups (P= 0.764), the ELISA titer and ELISA/MN titer ratio were significantly higher for patients with severe disease than for those with mild disease (P= 0.004 andP= 0.011, respectively). This finding suggested that in patients with severe disease, a larger proportion of serum antibodies were antibodies with no detectable neutralizing activity. The antibody avidity was also significantly higher in patients with severe disease than in those with mild disease (P< 0.05). Among patients with severe disease, those who required positive pressure ventilation (PPV) had significantly higher ELISA titers than those who did not require PPV (P< 0.05). Multivariate analysis showed that the ELISA titer and antibody avidity were independently associated with severe disease. Higher titers of nonneutralizing antibody with higher avidity at the early stage of influenza virus infection may be associated with worse clinical severity and poorer outcomes.

Vaccination of Rabbits with an Alkylated Toxoid Rapidly Elicits Potent Neutralizing Antibodies against Botulinum Neurotoxin Serotype B

ABSTRACT New Zealand White (NZW) rabbits were immunized with several different nontoxic botulinum neurotoxin serotype B (BoNT/B) preparations in an effort to optimize the production of a rapid and highly potent, effective neutralizing antibody response. The immunogens included a recombinant heavy chain (rHc) protein produced in Escherichia coli, a commercially available formaldehyde-inactivated toxoid, and an alkylated toxoid produced by urea-iodoacetamide inactivation of the purified active toxin. All three immunogens elicited an antibody response to BoNT/B, detected by enzyme-linked immunosorbent assay (ELISA) and by toxin neutralization assay, by the use of two distinct mouse toxin challenge models. The induction period and the ultimate potency of the observed immune response varied for each immunogen, and the ELISA titer was not reliably predictive of the potency of toxin neutralization. The kinetics of the BoNT/B-specific binding immune response were nearly identical for the formaldehyde toxoid and alkylated toxoid immunogens, but immunization with the alkylated toxoid generated an approximately 10-fold higher neutralization potency that endured throughout the study, and after just 49 days, each milliliter of serum was capable of neutralizing 107 50% lethal doses of the toxin. Overall, the immunization of rabbits with alkylated BoNT/B toxoid appears to have induced a neutralizing immune response more rapid and more potent than the responses generated by vaccination with formaldehyde toxoid or rHc preparations.

Study on the effects of Saccharomyces cerevisiae SC47 on broiler performance and immune organs

Several researches was conducted to investigate the effect of Saccharomyces cerevisiae on poultry performance, but Saccharomyces cerevisiae has an especial quality that makes its more noticeable for continuing research about its. This quality is:a) improving fatty acid digestibility (Kautz and Arens,1998), Improving of ether extract, cellulose digestibility and retention of nitrogen 2) improving of Phosphors digestibility(3) b) Stimulation of immunity c)improving of bronchitis and gambro Elisa titer d) have a several strain. According to this, an exprement was conducted to investigated the effects of SC47 on broilers performance and immune organs.

Altered Enzyme-Linked Immunosorbent Assay Immunoglobulin M (IgM)/IgG Optical Density Ratios Can Correctly Classify All Primary or Secondary Dengue Virus Infections 1 Day after the Onset of Symptoms, when All of the Viruses Can Be Isolated

ABSTRACT We compared dengue virus (DV) isolation rates and tested whether acute primary (P) and acute/probable acute secondary (S/PS) DV infections could be correctly classified serologically when the patients' first serum (S1) samples were obtained 1 to 3 days after the onset of symptoms (AOS). DV envelope/membrane protein-specific immunoglobulin M (IgM) capture and IgG capture enzyme-linked immunosorbent assay (ELISA) titrations (1/log10 1.7 to 1 log10 6.6 dilutions) were performed on 100 paired S1 and S2 samples from suspected DV infections. The serologically confirmed S/PS infections were divided into six subgroups based on their different IgM and IgG responses. Because of their much greater dynamic ranges, IgG/IgM ELISA titer ratios were more accurate and reliable than IgM/IgG optical density (OD) ratios recorded at a single cutoff dilution for discriminating between P and S/PS infections. However, 62% of these patients' S1 samples were DV IgM and IgG titer negative (<ODmax/2 titer threshold), and in 35% of the S/PS infections, the patients' S1 and S2 samples were IgM titer negative. The IgM OD values were, however, much higher than those of IgG in the S1 samples of many of these, and the other, S/PS infections. This necessitated using higher (≥2.60 and <2.60) discriminatory IgM/IgG OD (DOD) ratios on these S1 samples than those published previously to correctly classify the highest percentage of these P and S/PS infections. The DV isolation rate was highest (12/12; 100%) using IgG and IgM titer-negative S1 samples collected 1 day AOS, when 100% of them were correctly classified as P or S/PS infections using these higher DOD ratios.

Survey of Japanese Layer Farms for Salmonella Enteritidis with Vaccination- and Infection-Specific Antigens for Egg Yolk Antibodies

Japanese layer farms were surveyed for Salmonella Enteritidis vaccination and infection with specific antigens for egg yolk antibodies with the use of vaccination-specific antigen Salmonella Enteritidis FliC-specific 9-kDa polypeptide (SEP9) and infection-specific antigen deflagellated Salmonella Enteritidis whole cell (DEWC). The specific antibodies in eggs from 201 commercial layer farms throughout Japan were surveyed. The percentages of farm flocks with a mean enzyme-linked immunosorbent assay (ELISA) titer of over 0.1 were 56.2% (113 of 201) in DEWC-ELISA and 22.3% (45 of 201) in SEP9-ELISA. Flocks indicating high titers in SEP9-ELISA always showed high titers in DEWC-ELISA. Because both specific antibody titers of the vaccinated flocks monitored long term remained high throughout life, flocks with high titers of both ELISAs in this survey must be vaccinated. On the other hand, 34.3% (69 of 201) of flocks had high titers of DEWC-specific antibody alone. Because Salmonella Enteritidis infection induces the DEWC-specific antibody but not the SEP9-specific antibody, detecting only high ELISA titers of DEWC-specific antibody can be an effective monitoring tool for Salmonella Enteritidis exposure rather than vaccination. These results suggest that vaccination programs in Japanese layer farms would be insufficient to control Salmonella Enteritidis infection, and egg screening to detect specific antibodies would be valuable in obtaining the necessary information to control Salmonella Enteritidis infection.