Measles Virus IgG Avidity Assay for Use in Identification of Measles Vaccine Failures in Tianjin,China

Objective To identify measles vaccine failures in Tianjin, China using a measles virus Ig G avidity assay.Methods The China Information System for Disease Control and Prevention(CISDCP) was used to collect information about measles cases and blood specimens in Tianjin from 2013 to 2015. Measlesspecific Ig M and Ig G antibodies were detected using Enzyme-Linked Immunosorbent Assay(ELISA).Avidity testing for measles Ig G was performed using a commercial enzyme immunoassay(EIA).Results A total of 284 confirmed measles cases were identified. Of this total, 262(92.25%) were in patients aged ≥ 20 years. High avidity was exhibited in 172(60.56%) cases, while 80(28.17%) cases demonstrated low avidity. High avidity was detected in only 21.43% of cases in patients aged 1 year.The proportion of high avidity increased with age, and was significantly higher in patients aged 30–39 years at 70.07%(χ~2 = 17.27, P = 0.002). Of the 52 measles cases in patients with a history of vaccinations,41(78.85%) cases showed high avidity, indicating secondary vaccine failures(SVF). In these vaccinations,there was no significant difference(P 0.05) in clinical severity between high avidity and low avidity cases. However, regardless of vaccination status, clinical severity was significantly lower in high avidity cases(P 0.001) than in low avidity cases. The percentages of positive measles Ig M results in high avidity and low avidity cases were 66.28% and 91.25%, respectively. Geometric Mean Concentration(GMC) was significantly lower in high avidity cases at 33.73 U/m L, compared to 166.07 U/m L in low avidity cases.Conclusions Low clinical severity and inconclusive Ig M antibody results are more likely in high avidity measles cases. Measles cases were more common in adults. Therefore, a further dose of vaccines should be recommended for 30–39 years in Tianjin.     

Impact of wall shear stress and ligand avidity on binding of anti-CD146-coated nanoparticles to murine tumor endothelium under flow

The endothelial phenotype of tumor blood vessels differs from the liver and forms an important base for endothelium-specific targeting by antibody-coated nanoparticles. Although differences of shear stress and ligand avidity can modulate the nanoparticle binding to endothelium, these mechanisms are still poorly studied. This study analyzed the binding of antibody-coated nanoparticles to tumor and liver endothelium under controlled flow conditions and verified this binding in tumor models in vivo. Binding of anti-CD146-coated nanoparticles, but not of antibody was significantly reduced under increased wall shear stress and the degree of nanoparticle binding correlated with the avidity of the coating. The intravascular wall shear stress favors nanoparticle binding at the site of higher avidity of endothelial epitope which additionally promotes the selectivity to tumor endothelium. After intravenous application in vivo, pegylated self-coated nanoparticles showed specific binding to tumor endothelium, whereas the nanoparticle binding to the liver endothelium was very low. This study provides a rationale that selective binding of mAb-coated nanoparticles to tumor endothelium is achieved by two factors: higher expression of endothelial epitope and higher nanoparticle shearing from liver endothelium. The combination of endothelial marker targeting and the use of shear stress-controlled nanoparticle capture can be used for selective intratumoral drug delivery.     

Measurement of relative avidity of antibodies reactive with Porphyromonas (Bacteroides) gingivalis in the sera of subjects having adult periodontitis

Relative avidities of antibodies to Porphyromonas (Bacteroides) gingivalis in the sera of 15 patients having adult periodontitis and 15 healthy subjects were evaluated using an ammonium thiocyanate-dissociated ELISA. Graded concentrations of ammonium thiocyanate were added to a single dilution of serum in order to dissociate low avidity antibody binding to P. gingivalis . The concentration of thiocyanate resulting in 50% reduction in binding (absorbance) was termed the ID₅₀ for that serum. When IgG-class antibodies were examined, the ID₅₀ of anti- P. gingivalis antibodies in the sera of patients was significantly elevated (0.96M vs 0.71M; p<0.01, Student's t-test). In contrast, when IgM-class antibodies were examined no significant differences in ID₅₀ between patients and controls were found for P. gingivalis (0.54M vs 0.53M). While the ID₅₀ values of patient antibodies were found to be elevated relative to those of healthy controls, comparison with antibodies from rabbits immunized with P. gingivalis and with ID₅₀ values from other human studies suggests that adult humans, in general, produce very low-avidity antibodies to P. gingivalis . It is suggested that the presence of low-avidity antibodies contributes to the pathology associated with periodontal disease.     

Antibody response of Echinococcus granulosus infected mice: recognition of glucidic and peptidic epitopes and lack of avidity maturation

The antibody response was followed weekly during 68 weeks in 17 Balb/c mice intraperitoneally (i.p.) infected with 2000 Echinococcus granulosus protoscoleces (PSC) and in three mice i.p. immunized with 2000 dead PSC. Antibodies against hydatid cyst fluid (HCFA) and its peptidic (periodate-resistant) and carbohydrate (periodate-sensitive) epitopes were titrated by ELISA. Avidity and the antigen recognition pattern of antibodies were also analysed during infection and immunization by ELISA and immunoblot, respectively.
The antibody response of infected mice showed quantitative and qualitative variations during infection, since both titre as well as recognition of peptide and carbohydrate epitopes in HCFA depended on time post infection. No avidity maturation was evident during the course of infection. Sera from infected mice recognized the 38 kDa subunit of Ag5 but did not react with the 8 kDa subunit of AgB. On the contrary, the antibody response of immunized mice showed only one peak of antibodies that recognized both peptidic and carbohydrate epitopes of HCFA. In addition, sera from these mice recognized mainly 60 and 110 kDa bands. Our results suggest that: a) avidity and antigen recognition patterns of antibodies in mice treated with live PSC are different from those treated with dead PSC; b) antibodies against HCFA glucidic or peptidic epitopes appear at different times post infection.     

Antibodies to tetanus toxoid in women of childbearing age in Dar es Salaam and Bagamoyo, Tanzania

Our aim was to determine tetanus immunity in women of childbearing age (15-44 years) with histories and/or documentation of having been vaccinated with Tetanus Toxoid (TT) under the Expanded Programme on Immunization in Dar es Salaam and Bagamoyo, Tanzania. Using an ELISA technique, serum levels of TT antibody, antibody avidity and distribution of TT IgG subclass antibodies were determined in 207 apparently healthy women. A TT antibody level of 0.1 IU/ml was considered protective. 99% and 100% of women in Dar es Salaam and Bagamoyo, respectively, had a TT antibody level > or = 0.1 IU/ml. Anti-toxin binding avidity was found to be high in most of the women. In addition to TT IgG3 subclass antibody, TT IgG1 subclass antibody was the most dominant subclass type. A substantial number of women also had TT IgG2 and TT IgG4 subclass antibody responses. A better recording system on TT immunization is recommended to avoid hyper-immunization of women and to optimize the cost-effectiveness of the immunization programme.     

B- and T-cell memory elicited by a seasonal live attenuated reassortant influenza vaccine: assessment of local antibody avidity and virus-specific memory T-cells using trogocytosis-based method

Please cite this paper as: Petukhova et al. (2011) B‐ and T‐cell memory elicited by a seasonal live attenuated reassortant influenza vaccine: assessment of local antibody avidity and virus‐specific memory T‐cells using trogocytosis‐based method. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2011.00279.x. Purpose The main purpose of vaccination is to generate immunological memory providing enhanced immune responses against infectious pathogens. The standard and most commonly used assay for influenza vaccine immunogenicity evaluation is a hemagglutination inhibition assay (HAI). It is clear now that HAI assay is unable to properly assess the proven protective immunity elicited by live attenuated influenza vaccines (LAIV). New methods need to be developed for more accurate LAIV immunogenicity assessment and prediction of vaccine efficacy among target populations. Objective Randomized placebo‐controlled study of memory B‐ and T‐cell responses to intranasal LAIV in young adults. Methods A total of 56 healthy young adults 18–20 years old received seasonal monovalent LAIV. Mucosal memory B‐cell responses were measured by IgA avidity assessment in nasal swabs. CD4 memory T cells in peripheral blood were examined by the expression of CD45RO marker and in functional test by the ability of virus‐specific T cells to maintain the trogocytosis with antigen‐loaded target cells. Results Intranasal LAIV immunization enhances mucosal IgA avidity even without reliable increases in antibody titers. At the day 21 after vaccination, up to 40% of subjects demonstrated significant increases in both total and virus‐specific CD4 memory T cells that were observed regardless of seroconversion rate measured by HAI assay. Conclusion The data suggest that immunogenicity of LAIV vaccines should be evaluated on the mucosal and cellular immunity basis. The assays applied could be used to support influenza clinical trials through preliminary screening of volunteers and subsequent measurement of anti‐influenza in immunity.     

Selection of highly responsive T cell receptors by an analysis combining the expression of multiple markers

The clinical success of T cell receptor (TCR) gene–transduced T (TCR-T) cell therapy is expected as one of the next-generation immunotherapies for cancer, in which the selection of TCRs with high functional avidity (high-functional TCRs) is important. One widely used approach to select high-functional TCRs is a comparison of the EC50 values of TCRs, which involves laborious experiments. Therefore, the establishment of a simpler method to select high-functional TCRs is desired. We herein attempted to establish a simple method to select high-functional TCRs based on the expression of T cell activation markers using the mouse T cell line BW5147.3 (BW). We examined relationships between the EC50 values of TCRs in interleukin-2 production and the expression levels of TCR activation markers on BW cells. In TCR-expressing BW cells stimulated with antigenic peptides, the CD69, CD137, and PD-1 expression was differentially induced by various doses of peptides. An analysis of TCRs derived from the tumor-infiltrating lymphocytes of murine melanoma and peripheral blood T cells of hepatocellular carcinoma patients treated with a peptide vaccination revealed that an analysis combining CD69, CD137, and PD-1 expression levels in BW cells stimulated with a single dose of an antigenic peptide selected high-functional TCRs with functional avidity assessed by EC50 values. Our method facilitates the section of high-functional TCRs among tumor-reacting TCRs, which will promote TCR-T cell therapy. The stimulation of BW cells expressing objective TCRs with a single dose of antigenic peptides and analysis combining the expression of CD69, CD137, and PD-1 allows us to select highly responsive TCRs.     

Recruitment of epitope-specific T cell clones with a low-avidity threshold supports efficacy against mutational escape upon re-infection

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