Characterization and immunogenicity assessment of MERS-CoV pre-fusion spike trimeric oligomers as vaccine immunogen.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a lethal beta-coronavirus that emerged in 2012. The virus is part of the WHO blueprint priority list with a concerning fatality rate of 35%. Scientific efforts are ongoing for the development of vaccines, anti-viral and biotherapeutics, which are majorly directed toward the structural spike protein. However, the ongoing effort is challenging due to conformational instability of the spike protein and the evasion strategy posed by the MERS-CoV. In this study, we have expressed and purified the MERS-CoV pre-fusion spike protein in the Expi293F mammalian expression system. The purified protein was extensively characterized for its biochemical and biophysical properties. Thermal stability analysis showed a melting temperature of 58°C and the protein resisted major structural changes at elevated temperature as revealed by fluorescence spectroscopy and circular dichroism. Immunological assessment of the MERS-CoV spike immunogen in BALB/c mice with AddaVaxTM and Imject alum adjuvants showed elicitation of high titer antibody responses but a more balanced Th1/Th2 response with AddaVaxTM squalene like adjuvant. Together, our results suggest the formation of higher-order trimeric pre-fusion MERS-CoV spike proteins, which were able to induce robust immune responses. The comprehensive characterization of MERS-CoV spike protein warrants a better understanding of MERS spike protein and future vaccine development efforts.

Enhanced expression and solubility of main protease (Mpro) of SARS-CoV-2 from E. coli.

The main protease (Mpro) of SARS-CoV-2 is a essential enzyme that facilitates viral transcription and replication. Furthermore, the conservation of Mpro across different variants and its non-overlapping nature with human proteases make it an appealing target for therapeutic interventions against SARS-CoV-2. Multiple inhibitors specifically target Mpro to mitigate the infection caused by SARS-CoV-2. In the current study, successful cloning and expression of SARS-CoV-2 Mpro were achieved using two E. coli hosts, namely BL21-DE3 and BL21-DE3-RIL. By optimizing the conditions for induction, the expression of Mpro in the soluble fraction of E. coli was improved. Subsequently, Mpro was purified using affinity chromatography, yielding significantly higher quantities from the BL21-DE3-RIL strain compared to the BL21-DE3 strain, with the former producing nearly twice as much as the latter. The purified Mpro was further characterized by mass spectrometry, fluorescence spectroscopy and circular dichroism (CD). Through fluorescence quenching studies, it was discovered that both GC376 and chitosan, which are inhibitors of Mpro, induced structural changes in the purified Mpro protein. This indicates that the protein retained its functional activity even after being expressed in a bacterial host. Further, FRET-based assay highlighted that the enzymatic activity of Mpro was significantly reduced in presence of both GC376 and chitosan. Consequently, the utilization of optimal conditions and the BL21-DE3-RIL bacterial host facilitates the cost-effective production of Mpro on a large scale, enabling high yields. This production approach can be applied for the screening of potent therapeutic drugs, making it a valuable resource for drug development endeavors.

Immunogenicity Evaluation of Thermostable Microparticles Entrapping Receptor Binding Domain of SARS-CoV-2 by Single Point Administration.

Receptor binding domain (RBD) of SARS-CoV-2 is a prime vaccine target against which neutralizing antibody responses are directed. Purified RBD as a vaccine candidate warrants administration of multiple doses along with adjuvants and use of delivery systems to improve its immunogenicity. The present investigation examines the immunogenicity of RBD delivered by biodegradable polymer particles from single dose administration. Mice upon single point immunization of RBD entrapped microparticles generated improved antibody response. The polymer microparticles showed better temperature stability and could be stored at 37 degrees for one month without any considerable loss of immunogenicity. Further, immunization with microparticles could elicit memory antibody response upon challenge after four months of single dose administration. Thus, using microparticles entrapping RBD as a vaccine candidate confer improved immunogenicity, temperature stability and recall response. These thermostable microparticles seem to be a potentially cost-effective approach which can help in dose reduction, provide a wider access of vaccines and accelerate the end of global pandemic.

RBD decorated PLA nanoparticle admixture with aluminum hydroxide elicit robust and long lasting immune response against SARS-CoV-2.

Nanoparticles-based multivalent antigen display has the capability of mimicking natural virus infection characteristics, making it useful for eliciting potent long-lasting immune response. Several vaccines are developed against global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However these subunit vaccines use mammalian expression system, hence mass production with rapid pace is a bigger challenge. In contrast E. coli based subunit vaccine production circumvents these limitations. The objective of the present investigation was to develop nanoparticle vaccine with multivalent display of receptor binding domain (RBD) of SARS-CoV-2 expressed in E. coli. Results showed that RBD entrapped PLA (Poly lactic acid) nanoparticle in combination with aluminum hydroxide elicited 9-fold higher immune responses as compared to RBD adsorbed aluminum hydroxide, a common adjuvant used for human immunization. It was interesting to note that RBD entrapped PLA nanoparticle with aluminum hydroxide not only generated robust and long-lasting antibody response but also provided Th1 and Th2 balanced immune response. Moreover, challenge with 1 µg of RBD alone was able to generate secondary antibody response, suggesting that immunization with RBD-PLA nanoparticles has the ability to elicit memory antibody against RBD. Plaque assay revealed that the antibody generated using the polymeric formulation was able to neutralize SARS-CoV-2. The RBD entrapped PLA nanoparticles blended with aluminum hydroxide thus has potential to develop asa subunit vaccine against COVID-19.

Microparticles entrapping pneumococcal protein SP0845 show improved immunogenicity and temperature stability.

Protein based vaccines are the most safe and affordable strategy to combat pneumococcal disease circumventing the limitations of conventional polysaccharide-based vaccines like serotype dependence, high cost and inability to be administered to immunocompromised. SP0845 is a highly conserved vaccine candidate shown to provide protection against heterologous strains of Streptococcus pneumoniae, the primal cause of pneumonia. However, the associated poor immunogenicity warrants the need for adjuvants and multiple doses to mount desired responses. The present study relates to improve the immunogenicity of pneumococcal protein SP0845 by use of poly lactic acid biodegradable polymer microparticles. The immunization studies showed that microparticles elicited higher antibody response compared to alum adjuvanted protein and this immunopotentiation was achieved without the use of any additional adjuvant. They were also capable of eliciting secondary antibody response upon boosting after four months. Further, the particles upon storage at 25 and 37 °C for one month were still capable of mounting an immune response equivalent to those stored in cold chain. Thus, using microparticles entrapping SP0845 for immunization not only improve the immunogenicity but also offer better temperature stability. This can greatly reduce the cost and increase access of protein-based vaccine to resource limited settings.

Solubilization and refolding of variety of inclusion body proteins using a novel formulation.

Formation of protein aggregates as inclusion bodies (IBs) still poses a major hurdle in the recovery of bioactive proteins from E. coli. Despite the development of many mild solubilization buffers in last two decades, high-throughput recovery of functional protein from wide range of IBs is still a challenge at an academic and industrial scale. Herein, a novel formulation for improved recovery of bioactive protein from variety of bacterial IBs is developed. This novel formulation is comprised of 20% trifluoroethanol, 20% n-propanol and 2 M urea at pH 12.5 which disrupts the major dominant forces involved in protein aggregation. An extensive comparative study of novel formulation conducted on different IBs demonstrates its high solubilization and refolding efficiency. The overall yield of bioactive protein from human growth hormone expressed as bacterial IBs is reported to be around 50%. This is attributed to the capability of novel formulation to disrupt the tertiary structure of the protein while protecting the secondary structure of the protein, thereby reducing the formation of soluble aggregates during refolding. Thus, the formulation can eliminate the need of screening and optimizing various solubilization formulation and will improve the efficiency of recovering bioactive protein from variety of IB aggregates.

Polyangiitis overlap syndrome: a novel presentation of microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis.

Polyangiitis overlap syndrome (POS) is a diagnostic term coined by Leavitt and Fauci that characterises patients with overlapping features of more than one vasculitis. Prior case studies of antineutrophil cytoplasmic antibodies (ANCA)-associated POS have only been published in patients with eosinophilic granulomatosis with polyangiitis (EGPA) and granulomatosis with polyangiitis alongside proteinase-3/cytoplasmic (C)-ANCA positivity. We present a case of a 60-year-old woman with dyspnoea, hemoptysis, positive perinuclear-ANCA and renal biopsy demonstrating evidence of microscopic polyangiitis. In addition, our patient also had asthma, mononeuritis multiplex, eosinophilia and migratory pulmonary infiltrates, thus fulfilling the criteria for EGPA. This novel case report suggests that POS is not limited to C-ANCA positivity and has variable presentations.

Impact of Microbiota: A Paradigm for Evolving Herd Immunity against Viral Diseases.

Herd immunity is the most critical and essential prophylactic intervention that delivers protection against infectious diseases at both the individual and community level. This process of natural vaccination is immensely pertinent to the current context of a pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection around the globe. The conventional idea of herd immunity is based on efficient transmission of pathogens and developing natural immunity within a population. This is entirely encouraging while fighting against any disease in pandemic circumstances. A spatial community is occupied by people having variable resistance capacity against a pathogen. Protection efficacy against once very common diseases like smallpox, poliovirus or measles has been possible only because of either natural vaccination through contagious infections or expanded immunization programs among communities. This has led to achieving herd immunity in some cohorts. The microbiome plays an essential role in developing the body's immune cells for the emerging competent vaccination process, ensuring herd immunity. Frequency of interaction among microbiota, metabolic nutrients and individual immunity preserve the degree of vaccine effectiveness against several pathogens. Microbiome symbiosis regulates pathogen transmissibility and the success of vaccination among different age groups. Imbalance of nutrients perturbs microbiota and abrogates immunity. Thus, a particular population can become vulnerable to the infection. Intestinal dysbiosis leads to environmental enteropathy (EE). As a consequence, the generation of herd immunity can either be delayed or not start in a particular cohort. Moreover, disparities of the protective response of many vaccines in developing countries outside of developed countries are due to inconsistencies of healthy microbiota among the individuals. We suggested that pan-India poliovirus vaccination program, capable of inducing herd immunity among communities for the last 30 years, may also influence the inception of natural course of heterologous immunity against SARS-CoV-2 infection. Nonetheless, this anamnestic recall is somewhat counterintuitive, as antibody generation against original antigens of SARS-CoV-2 will be subdued due to original antigenic sin.

Effect of N-terminal poly histidine-tag on immunogenicity of Streptococcus pneumoniae surface protein SP0845.

SP0845, a pneumococcal surface protein and a potential candidate vaccine for Streptococcus pneumoniae infection, was used to evaluate the role of histidine affinity tag on its biophysical properties and immunogenicity. The protein was expressed in E. coli with and without histidine affinity tag and purified to homogeneity. Size exclusion chromatographic studies revealed that tag free SP0845 was mainly monomeric in solution whereas, histidine tagged SP0845 stayed predominantly in an oligomeric form. Histidine-tagged SP0845 have higher ß sheet content than the tag free protein. Removal of histidine tag increased the α-helical content of SP0845 from 35% to 46%. Histidine tagged SP0845 elicited higher serum antibody titer in comparison to the tag free SP0845 in mice. Effect of alum in improving the immunogenicity of tagged SP0845 was low in comparison to that observed with tag free protein. Immunogenicity of tag free SP0845 was enhanced by delivering it using polylactide polymeric particles. The presence of histidine tag thus influences the secondary structure and immunogenicity of protein and need careful consideration before use.

An Allosteric Anti-tryptase Antibody for the Treatment of Mast Cell-Mediated Severe Asthma.

Severe asthma patients with low type 2 inflammation derive less clinical benefit from therapies targeting type 2 cytokines and represent an unmet need. We show that mast cell tryptase is elevated in severe asthma patients independent of type 2 biomarker status. Active ß-tryptase allele count correlates with blood tryptase levels, and asthma patients carrying more active alleles benefit less from anti-IgE treatment. We generated a noncompetitive inhibitory antibody against human ß-tryptase, which dissociates active tetramers into inactive monomers. A 2.15 Å crystal structure of a ß-tryptase/antibody complex coupled with biochemical studies reveal the molecular basis for allosteric destabilization of small and large interfaces required for tetramerization. This anti-tryptase antibody potently blocks tryptase enzymatic activity in a humanized mouse model, reducing IgE-mediated systemic anaphylaxis, and inhibits airway tryptase in Ascaris-sensitized cynomolgus monkeys with favorable pharmacokinetics. These data provide a foundation for developing anti-tryptase as a clinical therapy for severe asthma.

Gene signatures common to allograft rejection are associated with lymphocytic bronchitis.

Lymphocytic bronchitis (LB) precedes chronic lung allograft dysfunction. The relationships of LB (classified here as Endobronchial or E-grade rejection) to small airway (A- and B-grade) pathologies are unclear. We hypothesized that gene signatures common to allograft rejection would be present in LB. We studied LB in two partially overlapping lung transplant recipient cohorts: Cohort 1 included large airway brushes (6 LB cases and 18 post-transplant referents). Differential expression using DESeq2 was used for pathway analysis and to define an LB-associated metagene. In Cohort 2, eight biopsies for each pathology subtype were matched with pathology-free biopsies from the same subject (totaling 48 samples from 24 subjects). These biopsies were analyzed by multiplexed digital counting of immune transcripts. Metagene score differences were compared by paired t tests. Compared to referents in Cohort 1, LB demonstrated upregulation of allograft rejection pathways, and upregulated genes in these cases characterized an LB-associated metagene. We observed statistically increased expression in Cohort 2 for this LB-associated metagene and four other established allograft rejection metagenes in rejection vs paired non-rejection biopsies for both E-grade and A-grade subtypes, but not B-grade pathology. Gene expression-based categorization of allograft rejection may prove useful in monitoring lung allograft health.

Donor-Reactive Regulatory T Cell Frequency Increases During Acute Cellular Rejection of Lung Allografts.

BACKGROUND: Acute cellular rejection is a major cause of morbidity after lung transplantation. Because regulatory T (Treg) cells limit rejection of solid organs, we hypothesized that donor-reactive Treg increase after transplantation with development of partial tolerance and decrease relative to conventional CD4 (Tconv) and CD8 T cells during acute cellular rejection. METHODS: To test these hypotheses, we prospectively collected 177 peripheral blood mononuclear cell specimens from 39 lung transplant recipients at the time of transplantation and during bronchoscopic assessments for acute cellular rejection. We quantified the proportion of Treg, CD4 Tconv, and CD8 T cells proliferating in response to donor-derived, stimulated B cells. We used generalized estimating equation-adjusted regression to compare donor-reactive T cell frequencies with acute cellular rejection pathology. RESULTS: An average of 16.5 ± 9.0% of pretransplantation peripheral blood mononuclear cell Treg cell were donor-reactive, compared with 3.8% ± 2.9% of CD4 Tconv and 3.4 ± 2.6% of CD8 T cells. These values were largely unchanged after transplantation. Donor-reactive CD4 Tconv and CD8 T cell frequencies both increased 1.5-fold (95% confidence interval [95% CI], 1.3-1.6; P < 0.001 and 95% CI, 1.2-1.6; P = 0.007, respectively) during grade A2 rejection compared with no rejection. Surprisingly, donor-reactive Treg frequencies increased by 1.7-fold (95% CI, 1.4-1.8; P < 0.001). CONCLUSIONS: Contrary to prediction, overall proportions of donor-reactive Treg cells are similar before and after transplantation and increase during grade A2 rejection. This suggests how A2 rejection can be self-limiting. The observed increases over high baseline proportions in donor-reactive Treg were insufficient to prevent acute lung allograft rejection.

Inhibition of inflammatory mediators: role of statins in airway inflammation.

OBJECTIVE: To determine if statins induce anti-inflammatory effects in upper airway inflammation. Mediators of innate and adaptive immunity regulate airway inflammation. Release of these mediators involves enzymatic conversion of polyunsaturated fatty acids into biologically active mediators, which can be blocked by statins. Although upper airway inflammation and chronic sinusitis occur in millions of patients with asthma worldwide, the anti-inflammatory effects of statins in upper airway inflammation have not been previously studied. STUDY DESIGN: Laboratory research. SETTING: Tertiary referral center. SUBJECTS AND METHODS: Analysis of sinus tissues collected from patients with chronic rhinosinusitis revealed suppression of highly expressed inflammatory mediators in patients who were found to be on statins, suggesting that statins may induce anti-inflammatory effects. Therefore, the authors performed an in vitro study to determine if these anti-inflammatory effects were induced by statins. Cultured primary human airway epithelial cells were exposed to ambient air pollution particulates (PM) to trigger the inflammation, with and without statins, and the expression of inflammatory mediators was analyzed. RESULTS: The authors found that expression of CCL5, CCL11, and IL13RA was suppressed in patients on statins. In vitro exposure to PM enhanced the expression of these mediators, while pretreatment with statins completely blocked these effects. Furthermore, the effects of statins were blocked by inhibition of the statin pathway using isopentenyl-5-pyrophosphate. Statins did not have any significant effect on the viability of normal cells. CONCLUSION: Statins induce anti-inflammatory effects in human airway epithelial inflammation. Statins may play a role in the treatment and prevention of chronic rhinosinusitis and pulmonary exacerbation of obstructive airway diseases.