Expression, Purification, and Refolding of Chikungunya Virus Full-Length Envelope E2 Protein along with B-Cell and T-Cell Epitope Analyses Using Immuno-Informatics Approaches

Purification and characterization of kyasanur forest disease virus EDIII domain of major envelope glycoprotein

Current research efforts are underway to create novel approaches for the efficient diagnosis, monitoring, and mitigation of Kyasanur Forest Disease Virus (KFDV) infections. Flavivirus subunit-based vaccines based on envelope glycoprotein EDIII are now in preclinical and clinical research stages. Efficient purification and isolation methods for surface immunogenic viral antigens, including the recombinant envelope immunoglobulin-like domain III (rEDIII) protein, are crucial for the production and manufacturing of promising vaccine candidates that have been extensively assessed in previous literature. Here, we describe a method for high-yield expression, purification, and refolding of a KFDV rEDIII protein from a bacterial expression system. The KFDV rEDIII protein is extracted from the inclusion bodies in urea denaturing buffer followed by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. The purified, denatured KFDV rEDIII protein was subsequently refolded using a step-wise gradient urea dilution via the dialysis method. The circular dichroism and Fourier transform infrared spectroscopy analysis confirms that the refolded KFDV rEDIII maintains the native secondary conformation majorly containing β-strands. Our study provides valuable insights into the design and expression strategies of rEDIII as a novel subunit vaccine candidate against KFDV.

Optimized high-yield expression of envelope glycoprotein domain III from dengue virus serotypes 1 to 4

Dengue virus (DENV) envelope glycoprotein Domain III (EDIII) is critical for viral entry, highly immunogenic, and induces robust neutralizing antibody response. It is a prominent candidate for designing subunit-based vaccines and can also be harnessed as an antigenic bait for isolation of neutralizing human mAbs. Here, we describe an optimized method for high-yield expression of recombinant domain EDIII protein from DENV serotypes 1 to 4 in different Escherichia coli (E. coli) expression strains. The DENV EDIII proteins show differential expression patterns in tested E. coli expression strains. The structural integrity of the purified and refolded proteins is further validated using the Circular Dichroism (CD) spectroscopy and Fourier Transform Infrared (FTIR) spectroscopic analysis. The functional validation of the purified refolded DENV EDIII proteins through Enzyme-linked Immunosorbent Assay (ELISA) and co-immunoprecipitation (Co-IP) exhibits efficient binding with a well-characterized humanized neutralizing mAb 513. Further, we compared the potency of purified EDIII in blocking viral through competitive inhibition assay. Our study highlights that a universal expression system may not be an ideal approach for all DENV EDIII protein expression.

Molecular cloning, expression, and purification, along with in silico epitope analysis of recombinant enolase proteins (a potential vaccine candidate) from Candida albicans and Candida auris

Candida albicans is the predominant cause of systemic candidiasis, although other non albicans Candida species are progressively becoming more widespread nowadays. Candida auris has emerged as a deadly multidrug-resistant fungal pathogen, posing a significant threat to global public health. In the absence of effective antifungal therapies, the development of a vaccine against C. auris infections is imperative. Enolase, a key glycolytic enzyme, has emerged as a promising vaccine candidate due to its immunogenic properties and essential role in fungal virulence. Herein, full-length Enolase gene sequences from C. albicans and C. auris were cloned into suitable expression vector and transformed into Escherichia coli expression hosts. Recombinant Enolase proteins were successfully expressed and purified using affinity chromatography under native conditions, followed by SDS-PAGE characterization and Western blot analysis. CD spectroscopy verified the existence of expressed proteins in soluble native conformation. Preliminary in silico studies verified the immunogenicity of recombinant Enolase proteins isolated from both C. albicans and C. auris. Furthermore, bioinformatics analysis revealed conserved B-cell and T-cell epitopes across C. albicans and C. auris Enolase proteins, suggesting potential cross-reactivity and broad-spectrum vaccine efficacy. Our findings are anticipated to play a role in advancing therapeutic as well as diagnostic strategies against systemic candidiasis.

Chikungunya Virus Diagnosis: A Review of Current Antigen Detection Methods

Chikungunya is a mosquito-borne viral disease caused by the chikungunya virus (CHIKV). CHIKV is expanding at an alarming rate, potentially spreading and establishing endemicity in new areas where competent vectors are present. The dramatic spread of CHIKV in recent years highlights the urgent need to take precautionary measures and investigate options for control. It is crucial in developing nations where diagnostic tools are limited, and symptoms are similar to other prevalent diseases such as malaria and dengue. The most reliable method for diagnosing chikungunya virus is viral gene detection by RT-PCR. Alternative methods like detecting human antibody and viral antigen can also be used, especially in areas where resources are limited. In this review, we summarize the limited data on antigen detection immunoassays. We further explain the essential structural elements of the virus to help comprehend the scientific concepts underlying the testing methods, as well as future methods and diagnostic approaches under investigation.

An Overview of Indian Biomedical Research on the Chikungunya Virus with Particular Reference to Its Vaccine, an Unmet Medical Need

Chikungunya virus (CHIKV) is an infectious agent spread by mosquitos, that has engendered endemic or epidemic outbreaks of Chikungunya fever (CHIKF) in Africa, South-East Asia, America, and a few European countries. Like most tropical infections, CHIKV is frequently misdiagnosed, underreported, and underestimated; it primarily affects areas with limited resources, like developing nations. Due to its high transmission rate and lack of a preventive vaccine or effective treatments, this virus poses a serious threat to humanity. After a 32-year hiatus, CHIKV reemerged as the most significant epidemic ever reported, in India in 2006. Since then, CHIKV-related research was begun in India, and up to now, more than 800 peer-reviewed research papers have been published by Indian researchers and medical practitioners. This review gives an overview of the outbreak history and CHIKV-related research in India, to favor novel high-quality research works intending to promote effective treatment and preventive strategies, including vaccine development, against CHIKV infection.

In silico design and validation of a novel multi-epitope vaccine candidate against structural proteins of Chikungunya virus using comprehensive immunoinformatics analyses

Chikungunya virus (CHIKV) is an emerging viral infectious agent with the potential of causing pandemic. There is neither a protective vaccine nor an approved drug against the virus. The aim of this study was design of a novel multi-epitope vaccine (MEV) candidate against the CHIKV structural proteins using comprehensive immunoinformatics and immune simulation analyses. In this study, using comprehensive immunoinformatics approaches, we developed a novel MEV candidate using the CHIKV structural proteins (E1, E2, 6 K, and E3). The polyprotein sequence was obtained from the UniProt Knowledgebase and saved in FASTA format. The helper and cytotoxic T lymphocytes (HTLs and CTLs respectively) and B cell epitopes were predicted. The toll-like receptor 4 (TLR4) agonist RS09 and PADRE epitope were employed as promising immunostimulatory adjuvant proteins. All vaccine components were fused using proper linkers. The MEV construct was checked in terms of antigenicity, allergenicity, immunogenicity, and physicochemical features. The docking of the MEV construct and the TLR4 and molecular dynamics (MD) simulation were also performed to assess the binding stability. The designed construct was non-allergen and was immunogen which efficiently stimulated immune responses using the proper synthetic adjuvant. The MEV candidate exhibited acceptable physicochemical features. Immune provocation included prediction of HTL, B cell, and CTL epitopes. The docking and MD simulation confirmed the stability of the docked TLR4-MEV complex. The high-level protein expression in the Escherichia coli (E. coli) host was observed through in silico cloning. The in vitro, in vivo, and clinical trial investigations are required to verify the findings of the current study.

Biophysical and biochemical insights in the design of immunoassays

BACKGROUND

Rapid antigen assays have been attractive for decentralized, point of care diagnostics because of their low cost, robustness, and ease of use. The development of a diagnostic assay for a newly emerging infectious disease needs to take into account the progression of a disease, whether there is human to human transmission, and patient biomarker levels with time, and these all impact the choice of antigen targets and affinity agents.

SCOPE OF REVIEW

The factors involved in the biophysical design of rapid antigen immunoassays are discussed, focusing on antigen selection and designing for cross-reactivity. State of the art in the biophysical characterization of protein-ligand or antigen-antibody interactions, the different types of affinity agents used in immunoassays, and biochemical conjugation strategies are described.

MAJOR CONCLUSIONS

Antigen choice is a critical factor in immunoassay diagnostic development, and should account for the properties of the virion, virus, and disease progression. Biophysical and biochemical aspects of immunoassays are critical for performance.

GENERAL SIGNIFICANCE

This review can serve as an instructive guide to aid in diagnostic development for future emerging diseases.