VLP-ELISA for the Detection of IgG Antibodies against Spike, Envelope, and Membrane Antigens of SARS-CoV-2 in Indian Population.

BACKGROUND: Serological methods to conduct epidemiological survey are often directed only against the spike protein. To overcome this limitation, we have designed PRAK-03202, a virus-like particle (VLP), by inserting three antigens (Spike, envelope and membrane) of SARS-CoV-2 into a highly characterized S. cerevisiae-based D-Crypt™ platform. METHODS: Dot blot analysis was performed to confirm the presence of S, E, and M proteins in PRAK-03202. The number of particles in PRAK-03202 was measured using nanoparticle tracking analysis (NTA). The sensitivity of VLP-ELISA was evaluated in 100 COVID positive. PRAK-03202 was produced at a 5 L scale using fed-batch fermentation. RESULTS: Dot blot confirmed the presence of S, E, and M proteins in PRAK-03202. The number of particles in PRAK-03202 was 1.21 × 109 mL-1. In samples collected >14 days after symptom onset, the sensitivity, specificity, and accuracy of VLP-ELISA were 96%. We did not observe any significant differences in sensitivity, specificity, and accuracy when post-COVID-19 samples were used as negative controls compared to pre-COVID-samples. At a scale of 5 L, the total yield of PRAK-03202 was 100-120 mg/L. CONCLUSION: In conclusion, we have successfully developed an in-house VLP-ELISA to detect IgG antibodies against three antigens of SARS-CoV-2 as a simple and affordable alternative test.

Platforms, advances, and technical challenges in virus-like particles-based vaccines.

Viral infectious diseases threaten human health and global stability. Several vaccine platforms, such as DNA, mRNA, recombinant viral vectors, and virus-like particle-based vaccines have been developed to counter these viral infectious diseases. Virus-like particles (VLP) are considered real, present, licensed and successful vaccines against prevalent and emergent diseases due to their non-infectious nature, structural similarity with viruses, and high immunogenicity. However, only a few VLP-based vaccines have been commercialized, and the others are either in the clinical or preclinical phases. Notably, despite success in the preclinical phase, many vaccines are still struggling with small-scale fundamental research owing to technical difficulties. Successful production of VLP-based vaccines on a commercial scale requires a suitable platform and culture mode for large-scale production, optimization of transduction-related parameters, upstream and downstream processing, and monitoring of product quality at each step. In this review article, we focus on the advantages and disadvantages of various VLP-producing platforms, recent advances and technical challenges in VLP production, and the current status of VLP-based vaccine candidates at commercial, preclinical, and clinical levels.

Establishment of a three­dimensional triculture model on the novel AXTEX­4D™ platform.

Cancer can be fatal if it is not treated in a timely manner; therefore, there is a high demand for more specific oncology drugs. Unfortunately, drugs showing positive responses on a two­dimensional (2D) culture platform do not often show the same effect in clinical trials. Therefore, three­dimensional (3D) culture platforms are garnering attention since they more closely mimic the tumor microenvironment (TME). The TME stimulates metastasis and drug resistance, and serves an essential role in tumor formation. An accurate understanding of tumor­stroma interactions is undoubtedly required to improve the response of patients to therapeutic strategies, and cancer therapeutic strategies that do not account for the stroma are considered inadequate. It should be noted that 3D monoculture systems do not completely mimic the TME since other cells in the 3D culture are missing, such as fibroblast or endothelial cells, which are essential components of the stroma; therefore, it is essential to develop advanced 3D culture systems. The present study aimed to develop a versatile triculture model that mimics the native TME; therefore, it could aid in high­throughput screening of chemotherapeutic drugs against cancer by evaluating their effects on tumor progression and cell cytotoxicity. The present study demonstrated the use of the AXTEX­4D™ platform in developing triculture tissueoids composed of MCF­7, human umbilical vein endothelial cells and MRC5 cells, and compared it with a 3D monoculture model (MCF­7) and a 2D culture model. The triculture model was validated for proliferation, ECM markers and T­cell infiltration by confocal microscopy. Alamar Blue assay demonstrated that triculture tissueoids exhibited higher drug resistance than the other two models, thus demonstrating their use in the screening of oncology drugs.

PRAK-03202: A triple antigen virus-like particle vaccine candidate against SARS CoV-2.

The rapid development of safe and effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is a necessary response to coronavirus outbreak. Here, we developed PRAK-03202, the world's first triple antigen virus-like particle vaccine candidate, by cloning and transforming SARS-CoV-2 gene segments into a highly characterized S. cerevisiae-based D-Crypt™ platform, which induced SARS CoV-2 specific neutralizing antibodies in BALB/c mice. Immunization using three different doses of PRAK-03202 induced an antigen-specific (spike, envelope, and membrane proteins) humoral response and neutralizing potential. Peripheral blood mononuclear cells from convalescent patients showed lymphocyte proliferation and elevated interferon levels suggestive of epitope conservation and induction of T helper 1-biased cellular immune response when exposed to PRAK-03202. These data support further clinical development and testing of PRAK-03202 for use in humans.

Corrigendum to "PRAK-03202: A triple antigen virus-like particle vaccine candidate against SARS CoV-2"[Heliyon 7 (10) (October 2021) e08124].

[This corrects the article DOI: 10.1016/j.heliyon.2021.e08124.].

AXTEX-4D: A Three-Dimensional Ex Vivo Platform for Preclinical Investigations of Immunotherapy Agents.

The latest advancements in oncology are majorly focused on immuno-oncology (I-O) therapies. However, only ∼7% of drugs are being approved from the preclinical discovery phase to phase 1. The most challenging issues in I-O are the development of active and efficient drugs in an economically feasible way and in a comparatively short time for testing and validation. This mandates an urgent need for the upgradation of preclinical screening models that closely mimic the in vivo tumor microenvironment (TME). The established and most common methods for investigating the tumoricidal activity of I-O drugs are either two-dimensional systems or primary tumor cells in standard tissue culture vessels. Unfortunately, they do not mimic the TME. Consequently, the more in vivo-like three-dimensional (3D) multicellular tumor spheroids are quickly becoming the favored model to examine immune cell-mediated responses in reaction to the administration of I-O drugs. Despite many advantages of multicellular spheroids, challenges (e.g., incompatibility of quantitative assays with spheroid platforms) are still involved in the tedious procedures required for the spheroid culture that is holding back the biological community from adapting the well-recognized spheroid tissue models for studying drug delivery more widely. To this end, we have demonstrated the utility of the 3D ex vivo oncology model, developed on our novel AXTEX-4D™ platform to assess therapeutic efficacies of I-O drugs by investigating immune cell proliferation, migration, infiltration, cytokine profiling, and cytotoxicity of tumor tissueoids. The platform eliminates the need for additional biomolecules such as hydrogels and instead relies on the cancer cells themselves to create their own gradients and microenvironmental factors. In effect, the more comprehensive and ex vivo-like immune-oncology model developed on AXTEX-4D platform can be utilized for high-throughput screening of immunotherapeutic drugs.