Recently Published Documents
Structure and computation-guided design of a mutation-integrated trimeric RBD candidate vaccine with broad neutralization against SARS-CoV-2
The spike (S) protein receptor-binding domain (RBD) of SARS-CoV-2 is an attractive target for COVID-19 vaccine developments, which naturally exists in a trimeric form. Here, guided by structural and computational analyses, we present a mutation-integrated trimeric form of RBD (mutI tri-RBD) as a broadly protective vaccine candidate, in which three RBDs were individually grafted from three different circulating SARS-CoV-2 strains including the prototype, Beta (B.1.351) and Kappa (B.1.617). The three RBDs were then connected end-to-end and co-assembled to possibly mimic the native trimeric arrangements in the natural S protein trimer. The recombinant expression of the mutI tri-RBD, as well as the homo-tri-RBD where the three RBDs were all truncated from the prototype strain, by mammalian cell exhibited correct folding, strong bio-activities, and high stability. The immunization of both the mutI tri-RBD and homo-tri-RBD plus aluminum adjuvant induced high levels of specific IgG and neutralizing antibodies against the SARS-CoV-2 prototype strain in mice. Notably, regarding to the immune-escape Beta (B.1.351) variant, mutI tri-RBD elicited significantly higher neutralizing antibody titers than homo-tri-RBD. Furthermore, due to harboring the immune-resistant mutations as well as the evolutionarily convergent hotspots, the designed mutI tri-RBD also induced strong broadly neutralizing activities against various SARS-CoV-2 variants, especially the variants partially resistant to homo-tri-RBD. Homo-tri-RBD has been approved by the China National Medical Products Administration to enter clinical trial (No. NCT04869592), and the superior broad neutralization performances against SARS-CoV-2 support the mutI tri-RBD as a more promising vaccine candidate for further clinical developments.
More knowledge regarding persistence of antibody response to SARS-CoV-2 infections in the general population with mild symptoms is needed. We measured and compared levels of SARS-CoV-2 spike- and nucleocapsid-specific IgG-antibodies in serum samples from 145 laboratory-confirmed COVID-19 cases and 324 non-cases. The IgG-antibody levels against the spike protein in cases were stable over the time-period studied (14 to 256 days), while antibody levels against the nucleocapsid protein decreased over time.
HER2-antigen-specific humoral immune response in breast cancer lymphocytes transplanted in hu-PBL hIL-4 NOG mice
AbstractThe status of humoral immunity of cancer patients is not clear compared to cellular immunity because the ability of specific antibody production is difficult to analyze in vitro. We previously developed a humanized mouse model to evaluate antigen-specific antibody production by transplanting human peripheral blood mononuclear cells (PBMCs) into NOG-hIL-4-Tg mice (hu-PBL hIL-4 NOG). In this study, these mice were transplanted with PBMCs derived from breast cancer patients (BC) and immunized with a human epidermal growth factor receptor 2 (HER2) peptide, CH401MAP, to analyze humoral immunity of BCs. The hu-PBL hIL-4 NOG mice recapitulated immune environment of BCs as the ratio of CD8+/CD4+T cells was lower and that of PD-1 + T cells was higher compared to healthy donors (HDs). Diverse clusters were detected in BC-mouse (BC-M) plasma components involving immunoglobulins and complements unlike HD-M, and there was a significant diversity in CH401MAP-specific IgG titers in BC-M. The number of B cell clones producing high CH401MAP-specific IgG was not increased by immunization in BC-M unlike HD-M. These results demonstrated that the humoral immunity of BCs appeared as diverse phenotypes different from HDs in hu-PBL hIL-4 NOG mice, which may provide important information for the study of personalized medicine.
Effects of Size and Surface Properties of Nanodiamonds on the Immunogenicity of Plant-Based H5 Protein of A/H5N1 Virus in Mice
Nanodiamond (ND) has recently emerged as a potential nanomaterial for nanovaccine development. Here, a plant-based haemagglutinin protein (H5.c2) of A/H5N1 virus was conjugated with detonation NDs (DND) of 3.7 nm in diameter (ND4), and high-pressure and high-temperature (HPHT) oxidative NDs of ~40–70 nm (ND40) and ~100–250 nm (ND100) in diameter. Our results revealed that the surface charge, but not the size of NDs, is crucial to the protein conjugation, as well as the in vitro and in vivo behaviors of H5.c2:ND conjugates. Positively charged ND4 does not effectively form stable conjugates with H5.c2, and has no impact on the immunogenicity of the protein both in vitro and in vivo. In contrast, the negatively oxidized NDs (ND40 and ND100) are excellent protein antigen carriers. When compared to free H5.c2, H5.c2:ND40, and H5.c2:ND100 conjugates are highly immunogenic with hemagglutination titers that are both 16 times higher than that of the free H5.c2 protein. Notably, H5.c2:ND40 and H5.c2:ND100 conjugates induce over 3-folds stronger production of both H5.c2-specific-IgG and neutralizing antibodies against A/H5N1 than free H5.c2 in mice. These findings support the innovative strategy of using negatively oxidized ND particles as novel antigen carriers for vaccine development, while also highlighting the importance of particle characterization before use.
SARS-CoV-2 spike antigen-specific IgG and IgA elicited by infection mediate viral neutralization and are likely an important component of natural immunity, however, limited information exists on vaccine induced responses. We measured COVID-19 mRNA vaccine induced IgG and IgA in serum serially, up to 145 days post vaccination in 4 subjects. Spike antigen-specific IgG levels rose exponentially and plateaued 21 days after the initial vaccine dose. After the second vaccine dose IgG levels increased further, reaching a maximum approximately 7–10 days later, and remained elevated (average of 58% peak levels) during the additional >100 day follow up period. COVID-19 mRNA vaccination elicited spike antigen-specific IgA with similar kinetics of induction and time to peak levels, but more rapid decline in serum levels following both the 1st and 2nd vaccine doses (<18% peak levels within 100 days of the 2nd shot). The data demonstrate COVID-19 mRNA vaccines effectively induce spike antigen specific IgG and IgA and highlight marked differences in their persistence in serum.
Declining Levels of Neutralizing Antibodies Against SARS-CoV-2 in Convalescent COVID-19 Patients One Year Post Symptom Onset
Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies recognizing the nucleocapsid (N) protein or the receptor binding domain (RBD) of the spike protein (S). After one year, approximately 90% of recovered patients still had detectable SARS-CoV-2-specific IgG antibodies recognizing N and RBD-S. Intriguingly, neutralizing activity was only detectable in ~43% of patients. When neutralization tests against the E484K-mutated variant of concern (VOC) B.1.351 (initially identified in South Africa) were performed among patients who neutralize the original virus, the capacity to neutralize was even further diminished to 22.6% of donors. Despite declining N- and S-specific IgG titers, a considerable fraction of recovered patients had detectable neutralizing activity one year after infection. However, neutralizing capacities, in particular against an E484K-mutated VOC were only detectable in a minority of patients one year after symptomatic COVID-19. Our findings shed light on the kinetics of long-term immune responses after natural SARS-CoV-2 infection and argue for vaccinations of individuals who experienced a natural infection to protect against emerging VOC.
Vaccines that elicit mucosal immune responses against SARS-CoV-2 could potentially be of exceptional importance in providing first line defense at the site of viral entry. The serological antibody response induced by SARS-CoV-2 vaccines have already been well characterized. In order to understand the mucosal immune response profiles of SARS-CoV-2 vaccines, we examined both the mucosal and systemic responses of subjects vaccinated by two different vaccination platforms: mRNA (Comirnaty) and inactivated virus (CoronaVac). Serial nasal epithelial lining fluid (NELF) and peripheral blood samples were collected in ten subjects who had received CoronaVac and thirty-two subjects who had received Comirnaty. We quantified IgA and IgG specific to SARS-CoV-2 S1 protein by ELISA in NELF and plasma samples. The neutralization effect of these two sample types were evaluated by surrogate ACE-SARS-CoV-2 Spike protein ELISA. Only Comirnaty induced nasal SARS-CoV-2 S1 protein-specific (S1-specific) IgA and IgG responses, which were evident as early as on 14 days after the first dose. The NELF samples of 72% of subjects became IgA+IgG+, while in 62.5% of subjects the samples were neutralizing by 7 days after the second dose. In 45% of the subjects their NELF remained neutralizing 50 days after the booster of Comirnaty. In plasma, 91% and 100% Comirnaty subjects possessed S1-specific IgA+IgG+ on 14 days after the first dose and 7 days after booster, respectively. The plasma collected on 7 days after booster was 100% neutralizing. The induction of S1-specific antibody by CoronaVac was IgG dominant, and 70% of the subjects possessed S1-specific IgG by 7 days after booster and were all neutralizing. This study reveals that Comirnaty is able to induce S1-specific IgA and IgG response with neutralizing activity in the nasal mucosa in addition to a consistent systemic response. The clinical implications and the biological mechanism of an additional nasal immune response induced by vaccines such as Comirnaty warrant further investigation.
BackgroundSeveral studies indicate that Der p 7 is an important and clinically relevant allergen of Dermatophagoides pteronyssinus which should be included in vaccines for treatment of house dust mite (HDM) allergy. Aim of this study was to characterize the IgE epitopes of Der p 7.MethodsRecombinant Der p 7 was expressed and purified, analyzed for fold by circular dichroism and tested for its allergenic activity by basophil activation. Seven overlapping, surface-exposed peptides (P1–P7) with a length of 27 to 37 amino acids, which spanned the Der p 7 sequence, were synthesized and tested for IgE reactivity and allergenic activity by basophil activation assay. Carrier-bound peptides were studied for their ability to induce allergen-specific IgG antibodies in rabbits. Peptide-specific antibodies were used to inhibit allergic patients` IgE binding to Der p 7 by ELISA for mapping of IgE epitopes.ResultsrDer p 7 showed high allergenic activity comparable with Der p 5, Der p 21, and Der p 23. None of the seven tested peptides showed any IgE reactivity or allergenic activity when tested with HDM- allergic patients indicating lack of sequential IgE epitopes on Der p 7. IgE inhibition experiments using anti-peptide specific IgGs and molecular modeling enabled us to identify discontinuous, conformational IgE epitopes of Der p 7.Conclusion and Clinical RelevanceIgE epitopes of Der p 7 belong to the conformational and discontinuous type whereas sequential Der p 7 peptides lack IgE reactivity. It should thus be possible to construct hypoallergenic vaccines for Der p 7 based on carrier-bound allergen peptides.
Immunogenicity and reactogenicity of a heterologous COVID-19 prime-boost vaccination compared with homologous vaccine regimens
Heterologous priming with the ChAdOx1-nCoV-19 vector-vaccine followed by boosting with an mRNA-vaccine is currently recommended in Germany, although data on immunogenicity and reactogenicity are not available. Here we show that the heterologous regimen induced spike-specific IgG, neutralizing antibodies, and spike-specific CD4 T-cells, which were significantly more pronounced than after homologous vector boost, and higher or comparable in magnitude to the homologous mRNA regimens. Moreover, spike-specific CD8 T-cell levels after heterologous vaccination were significantly higher than after both homologous regimens. Cytokine expression profiling showed a predominance of polyfunctional T-cells expressing IFNγ, TNFα and IL-2 with subtle differences between regimens. Both recipients of the homologous vector-regimen and the heterologous vector/mRNA-combination were most affected by the priming vector-vaccination, whereas heterologous boosting was well tolerated and comparable to homologous mRNA-boosting. Taken together, heterologous vector-mRNA boosting induces strong humoral and cellular immune responses with acceptable reactogenicity profile. This knowledge will have implications for future vaccine strategies.
Establishing Aspergillus-Specific IgG Cut-Off Level for Chronic Pulmonary Aspergillosis Diagnosis: Multicenter Prospective Cohort Study
Objectives: Aspergillus-specific IgG (Asp-IgG) cut-off level in diagnosing chronic pulmonary aspergillosis (CPA) remains unknown. Methods: We prospectively recruited participants with clinical suspicion of CPA in three centers in Taiwan during 2019 June to 2020 August. Serum Aspergillus fumigatus-specific IgG (Asp-IgG) (Phadia, Uppsala, UPPS, Sweden) was examined. Optimal cut-off level was determined by Youden’s index and validated. Results: A total of 373 participants were recruited. In the derivation cohort (n = 262), Asp-IgG had an area under the receiver-operating-characteristic curve (AUC) of 0.832. The optimal cut-off level was 40.5 mgA/L. While applying this cut-off level to the validation cohort (n = 111), the sensitivity and specificity were 86.7% and 80.2%. Lowering the cut-off level from 40.5 to 27 mgA/L, the sensitivity was steady (30/36, 83.3% to 31/36, 86.1%) while specificity dropped from 81.9% (276/337) to 63.5% (214/337). Restricting CPA diagnosis to only chronic cavitary pulmonary aspergillosis (CCPA) and chronic fibrosing pulmonary aspergillosis (CFPA) yielded a cut-off level of 42.3 mgA/L in the derivation cohort with a sensitivity of 100% and specificity of 84.4% in the validation cohort. Conclusions: Serum Asp-IgG performs well for CPA diagnosis and provides a low false-positive rate when using a higher cut-off level (preferably around 40 mgA/L).