Leveraging the immunoinformatics approach for designing the SARS-CoV-2 omicron-specific antigenic cassette of mRNA vaccine

Transfection via RNA-Based Nanoparticles: Comparing Encapsulation vs Adsorption Approaches of RNA Incorporation

Historically, RNA delivery via nanoparticles has primarily relied on encapsulation, as demonstrated by lipid nanoparticles in SARS-CoV-2 vaccines. Concerns about RNA degradation on nanoparticle surfaces initially limited the exploration of adsorption-based approaches. However, recent advancements have renewed interest in adsorption as a viable alternative. This Viewpoint explores the approaches of RNA incorporation in nanoparticles, comparing encapsulation, adsorption, and the combination of encapsulation and adsorption, and presents a framework to guide the selection of the most suitable strategy based on general characteristics.

Cellular immune breadth of an Omicron-specific, self-amplifying monovalent mRNA vaccine booster for COVID-19

Selecting a booster vaccine strategy that generates cellular immune breadth is crucial for effectively recalling cellular reservoirs upon infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants. This post hoc analysis from a multicentre, randomized phase 3 study (CTRI/2022/10/046475) compared the cellular immune breadth induced by self-replicating mRNA (samRNA) vaccine GEMCOVAC-OM, encoding Omicron B.1.1.529 Spike protein, with the adenovector vaccine ChAdOx1 nCoV-19, encoding Wuhan variant Spike protein, when administered as a booster. GEMCOVAC-OM elicited significant expansion of memory B-cells (MBCs) specific to Omicron B.1.1.529, compared to ChAdOx1 nCoV-19. GEMCOVAC-OM also induced more B-cells reactive to Omicron XBB.1.5 and BA.2.86 Spike proteins. Additionally, GEMCOVAC-OM triggered higher frequencies of Omicron-Spike-specific T-cells, including stem cell, central, and effector memory subsets. In summary, while ChAdOx1 nCoV-19 showed some cross-reactivity, GEMCOVAC-OM induced a more targeted immune response. GEMCOVAC-OM offers a broader, longer-lasting immunity, making it a promising candidate for future vaccine development and global distribution.

Leveraging Next-Generation Sequencing Application from Identity to Purity Profiling of Nucleic Acid-Based Products

Background/Objectives: The nucleic acid-based product (NAP) portfolio is expanding continuously and provides safer curative options for many disease indications. Nucleic acid-based products offer several advantages compared to proteins and virus-based products. They represent an emerging field; thus, their quality control and regulatory landscape is evolving to ensure adequate quality and safety. Next-Generation Sequencing (NGS) is mostly recommended for NAP identity testing, and we are leveraging its application for impurity profiling. Methods: We proposed a workflow for the purity assessment of NAPs through short-read Illumina NGS followed by data analysis of mRNA vaccine and pDNA samples. We determined the sequence identity, DNA and RNA contamination, off-target RNA contamination, and poly-A count with the proposed workflow. Results: Our workflow predicted most of the critical quality controls of mRNA vaccine and plasmid DNA samples, especially focusing on the identity and the nucleotide-based impurities. Additionally, NGS data interpretation also assisted in strategic decisions for NAP manufacturing process optimizations. Conclusions: We recommend the adaptation of incremental NGS data by regulatory agencies to identify nucleotide-based impurities in NAPs. Perhaps NGS adaptation under cGMP compliance needs to be deliberated with the regulatory bodies, especially focusing on the methods qualification and validation part, starting from the sample collection, NGS library preparation, NGS run, and its data analysis pipeline.

Combinative workflow for mRNA vaccine development

Recently, mRNA has gained a lot of attention in the field of vaccines, gene therapy, and protein replacement therapies. Herein, we are demonstrating a comprehensive approach to designing, cloning, and characterizing an antigenic cassette for the development of mRNA vaccine for COVID-19. The gene encoding the antigenic spike protein of the SARS-CoV-2 Omicron variant (B.1.1.529) was designed using the databases, characterized by in-silico tools, and assembled using overlapping oligonucleotide-based assembly by PCR. Next, the gene was cloned, mRNA was synthesized, and characterized using orthogonal approaches (Capillary electrophoresis, Sanger DNA sequencing, Next-generation sequencing, HPLC, qPCR, etc.). Furthermore, the antigen expression was monitored in-vitro using an animal cell model by western blot, flow cytometer, and surface plasmon resonance. The demonstrated approach has also been followed for developing the mRNA vaccines for various other indications such as Malaria, Herpes, Dengue, HPV, etc.

An Omicron-specific, self-amplifying mRNA booster vaccine for COVID-19: a phase 2/3 randomized trial

Here we conducted a multicenter open-label, randomized phase 2 and 3 study to assess the safety and immunogenicity of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron-specific (BA.1/B.1.1.529), monovalent, thermostable, self-amplifying mRNA vaccine, GEMCOVAC-OM, when administered intradermally as a booster in healthy adults who had received two doses of BBV152 or ChAdOx1 nCoV-19. GEMCOVAC-OM was well tolerated with no related serious adverse events in both phase 2 and phase 3. In phase 2, the safety and immunogenicity of GEMCOVAC-OM was compared with our prototype mRNA vaccine GEMCOVAC-19 (D614G variant-specific) in 140 participants. At day 29 after vaccination, there was a significant rise in anti-spike (BA.1) IgG antibodies with GEMCOVAC-OM (P < 0.0001) and GEMCOVAC-19 (P < 0.0001). However, the IgG titers (primary endpoint) and seroconversion were higher with GEMCOVAC-OM (P < 0.0001). In phase 3, GEMCOVAC-OM was compared with ChAdOx1 nCoV-19 in 3,140 participants (safety cohort), which included an immunogenicity cohort of 420 participants. At day 29, neutralizing antibody titers against the BA.1 variant of SARS-CoV-2 were significantly higher than baseline in the GEMCOVAC-OM arm (P < 0.0001), but not in the ChAdOx1 nCoV-19 arm (P = 0.1490). GEMCOVAC-OM was noninferior (primary endpoint) and superior to ChAdOx1 nCoV-19 in terms of neutralizing antibody titers and seroconversion rate (lower bound 95% confidence interval of least square geometric mean ratio >1 and difference in seroconversion >0% for superiority). At day 29, anti-spike IgG antibodies and seroconversion (secondary endpoints) were significantly higher with GEMCOVAC-OM (P < 0.0001). These results demonstrate that GEMCOVAC-OM is safe and boosts immune responses against the B.1.1.529 variant. Clinical Trial Registry India identifier: CTRI/2022/10/046475 .