A perspective on SARS-CoV-2 virus-like particles vaccines

Rapid and Scalable Production of Functional SARS-CoV-2 Virus-like Particles (VLPs) by a Stable HEK293 Cell Pool

At times of pandemics, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the situation demands rapid development and production timelines of safe and effective vaccines for delivering life-saving medications quickly to patients. Typical biologics production relies on using the lengthy and arduous approach of stable single-cell clones. Here, we used an alternative approach, a stable cell pool that takes only weeks to generate compared to a stable single-cell clone that needs several months to complete. We employed the membrane, envelope, and highly immunogenic spike proteins of SARS-CoV-2 to produce virus-like particles (VLPs) using the HEK293-F cell line as a host system with an economical transfection reagent. The cell pool showed the stability of protein expression for more than one month. We demonstrated that the production of SARS-CoV-2 VLPs using this cell pool was scalable up to a stirred-tank 2 L bioreactor in fed-batch mode. The purified VLPs were properly assembled, and their size was consistent with the authentic virus. Our particles were functional as they specifically entered the cell that naturally expresses ACE-2. Notably, this work reports a practical and cost-effective manufacturing platform for scalable SARS-CoV-2 VLPs production and chromatographic purification.

Both recombinant Bacillus subtilis Expressing PCV2d Cap protein and PCV2d-VLPs can stimulate strong protective immune responses in mice

Porcine circovirus type 2 (PCV2) is one of the most serious pathogens in pig herds worldwide. The Capsid protein (Cap), a structural protein of PCV2, is involved in the host's immune response; it induces neutralizing-antibody production and has good immunogenicity. The main PCV2 subtype currently prevalent in the Chinese pig herd is PCV2d. In this study, We constructed a recombinant Bacillus subtilis (B. subtilis) capable of secreting Cap protein, named pHT43-Cap/B. subtilis; we concentrated the supernatant of the recombinant bacteria and observed virus-like particles (VLPs) of PCV2d formed by Cap protein under transmission electron microscopy, named PCV2d-VLPs. The immunocompetence of the pHT43-Cap/B. subtilis and PCV2d-VLPs were then assessed by oral administration and by intramuscular injection into mice, respectively. The results showed that the levels of PCV2d-Cap protein-specific IgG in the serum and of PCV2d-Cap protein-specific sIgA in the small intestinal fluid of pHT43-Cap/B. subtilis immunized mice were elevated compared to the control group, both of them highly significant (p < 0.01), and the corresponding serum-specific IgG antibodies were effective in neutralizing PCV2d virulence. The virus load in the liver of the immunized mice was significantly lower than that in the control group (p < 0.01), as was the virus load in the spleen and lungs of the immunized mice (p < 0.05). In addition, the serum levels of PCV2d-Cap-specific IgG in mice immunized with PCV2d-VLPs by intramuscular injection were significantly elevated compared to the control group (p < 0.05), and the viral load in all tissues was significantly lower in immunized mice (p < 0.05). In conclusion, the recombinant bacterium pHT43-Cap/B. subtilis can induce effective mucosal and humoral immunity in mice, PCV2d-VLPs can induce humoral immunity in mice, and both vaccines have good immunogenicity; these results provide a theoretical and material basis for the development of a new vaccine against PCV2d.

Nanovaccines: A game changing approach in the fight against infectious diseases

The field of nanotechnology has revolutionised global attempts to prevent, treat, and eradicate infectious diseases in the foreseen future. Nanovaccines have proven to be a valuable pawn in this novel technology. Nanovaccines are made up of nanoparticles that are associated with or prepared with components that can stimulate the host's immune system. In addition to their delivery capabilities, the nanocarriers have been demonstrated to possess intrinsic adjuvant properties, working as immune cell stimulators. Thus, nanovaccines have the potential to promote rapid as well as long-lasting humoral and cellular immunity. The nanovaccines have several possible benefits, including site-specific antigen delivery, increased antigen bioavailability, and a diminished adverse effect profile. To avail these benefits, several nanoparticle-based vaccines are being developed, including virus-like particles, liposomes, polymeric nanoparticles, nanogels, lipid nanoparticles, emulsion vaccines, exomes, and inorganic nanoparticles. Inspired by their distinctive properties, researchers are working on the development of nanovaccines for a variety of applications, such as cancer immunotherapy and infectious diseases. Although a few challenges still need to be overcome, such as modulation of the nanoparticle pharmacokinetics to avoid rapid elimination from the bloodstream by the reticuloendothelial system, The future prospects of this technology are also assuring, with multiple options such as personalised vaccines, needle-free formulations, and combination nanovaccines with several promising candidates.

COVID-19 Vaccine in Renal Transplant Recipients: A Bibliometric-Based Analysis of Trends

BACKGROUND

The global community has been affected by COVID-19, which emerged in December 2019. Since then, many studies have been conducted on kidney transplant recipients (KTRs) and COVID-19. This study aimed to perform a bibliometric and visual analysis of the published relationship between KTRs and COVID-19.

OBJECTIVE

To discuss the current status, hot spots, and development trend of research on KTRs vaccination with the COVID-19 vaccine and to provide a reference for researchers in related fields.

METHODS

Visual analysis of countries/regions, institutions, authors, references cited, and keywords for 2020 to 2023 via Microsoft Office Excel 2019 and CiteSpace (6.1.R6) based on the Web of Science core database.

RESULTS

A total of 366 publications were included after screening, with a rapid increase in the global literature studying the COVID-19 vaccine of KTRs. The US has the highest number of publications, indicating that it is the leading country in this field of research. Charite University of Medicine Berlin and Schrezenmeier E are the most published institutions and authors, respectively. "Antibody Response After a Third Dose of the messenger RNA-1273 SARS-CoV-2 Vaccine in Kidney Transplant Recipients With Minimal Serologic Response to 2 Doses" is the most central co-cited reference; The keywords "kidney transplant recipient," "covid 19 vaccine," and "mortality" have become hot topics of research. The keywords "humoral response" and "bnt162b2" are the latest research frontiers for detecting bursts.

CONCLUSIONS

This paper analyzed the current status and trends of vaccination studies in KTRs through bibliometric analysis. Several studies support the vaccination of KTRs with the COVID-19 vaccine. However, the evidence for improving vaccine efficacy by adjustment of immunosuppression is still limited, and future studies on vaccination will remain a hot topic in this field.

Study of the Effects of Several SARS-CoV-2 Structural Proteins on Antiviral Immunity

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike (S) protein is a critical viral antigenic protein that enables the production of neutralizing antibodies, while other structural proteins, including the membrane (M), nucleocapsid (N) and envelope (E) proteins, have unclear roles in antiviral immunity. In this study, S1, S2, M, N and E proteins were expressed in 16HBE cells to explore the characteristics of the resultant innate immune response. Furthermore, peripheral blood mononuclear cells (PBMCs) from mice immunized with two doses of inactivated SARS-CoV-2 vaccine or two doses of mRNA vaccine were isolated and stimulated by these five proteins to evaluate the corresponding specific T-cell immune response. In addition, the levels of humoral immunity induced by two-dose inactivated vaccine priming followed by mRNA vaccine boosting, two homologous inactivated vaccine doses and two homologous mRNA vaccine doses in immunized mice were compared. Our results suggested that viral structural proteins can activate the innate immune response and elicit a specific T-cell response in mice immunized with the inactivated vaccine. However, the existence of the specific T-cell response against M, N and E is seemingly insufficient to improve the level of humoral immunity.

The Global Impact of COVID-19: Historical Development, Molecular Characterization, Drug Discovery and Future Directions

In December 2019, an outbreak of a respiratory disease called the coronavirus disease 2019 (COVID-19) caused by a new coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in Wuhan, China. The SARS-CoV-2, an encapsulated positive-stranded RNA virus, spread worldwide with disastrous consequences for people's health, economies, and quality of life. The disease has had far-reaching impacts on society, including economic disruption, school closures, and increased stress and anxiety. It has also highlighted disparities in healthcare access and outcomes, with marginalized communities disproportionately affected by the SARS-CoV-2. The symptoms of COVID-19 range from mild to severe. There is presently no effective cure. Nevertheless, significant progress has been made in developing COVID-19 vaccine for different therapeutic targets. For instance, scientists developed multifold vaccine candidates shortly after the COVID-19 outbreak after Pfizer and AstraZeneca discovered the initial COVID-19 vaccines. These vaccines reduce disease spread, severity, and mortality. The addition of rapid diagnostics to microscopy for COVID-19 diagnosis has proven crucial. Our review provides a thorough overview of the historical development of COVID-19 and molecular and biochemical characterization of the SARS-CoV-2. We highlight the potential contributions from insect and plant sources as anti-SARS-CoV-2 and present directions for future research.