Preclinical Immune Response and Safety Evaluation of the Protein Subunit Vaccine Nanocovax for COVID-19

CHO cells for virus-like particle and subunit vaccine manufacturing

Chinese Hamster Ovary (CHO) cells, employed primarily for manufacturing monoclonal antibodies and other recombinant protein (r-protein) therapeutics, are emerging as a promising host for vaccine antigen production. This is exemplified by the recently approved CHO cell-derived subunit vaccines (SUV) against respiratory syncytial virus (RSV) and varicella-zoster virus (VZV), as well as the enveloped virus-like particle (eVLP) vaccine against hepatitis B virus (HBV). Here, we summarize the design, production, and immunogenicity features of these vaccine and review the most recent progress of other CHO-derived vaccines in pre-clinical and clinical development. We also discuss the challenges associated with vaccine production in CHO cells, with a focus on ensuring viral clearance for eVLP products.

Autoimmune response after SARS-CoV-2 infection and SARS-CoV-2 vaccines

The complicated relationships between autoimmunity, COVID-19, and COVID-19 vaccinations are described, giving insight into their intricacies. Antinuclear antibodies (ANA), anti-Ro/SSA, rheumatoid factor, lupus anticoagulant, and antibodies against interferon (IFN)-I have all been consistently found in COVID-19 patients, indicating a high prevalence of autoimmune reactions following viral exposure. Furthermore, the discovery of human proteins with structural similarities to SARS-CoV-2 peptides as possible autoantigens highlights the complex interplay between the virus and the immune system in initiating autoimmunity. An updated summary of the current status of COVID-19 vaccines is presented. We present probable pathways underpinning the genesis of COVID-19 autoimmunity, such as bystander activation caused by hyperinflammatory conditions, viral persistence, and the creation of neutrophil extracellular traps. These pathways provide important insights into the development of autoimmune-related symptoms ranging from organ-specific to systemic autoimmune and inflammatory illnesses, demonstrating the wide influence of COVID-19 on the immune system.

Protein subunit vaccines: Promising frontiers against COVID-19

The emergence of COVID-19 has posed an unprecedented global health crisis, challenging the healthcare systems worldwide. Amidst the rapid development of several vaccine formulations, protein subunit vaccines have emerged as a promising approach. This article provides an in-depth evaluation of the role of protein subunit vaccines in the management of COVID-19. Leveraging viral protein fragments, particularly the spike protein from SARS-CoV-2, these vaccines elicit a targeted immune response without the risk of inducing disease. Notably, the robust safety profile of protein subunit vaccines makes them a compelling candidate in the management of COVID-19. Various innovative approaches, including reverse vaccinology, virus like particles, and recombinant modifications are incorporated to develop protein subunit vaccines. In addition, the utilization of advanced manufacturing techniques facilitates large-scale production, ensuring widespread distribution. Despite these advancements, challenges persist, such as the requirement for cold-chain storage and the necessity for booster doses. This article evaluates the formulation and applications of protein subunit vaccines, providing a comprehensive overview of their clinical development and approvals in the context of COVID-19. By addressing the current status and challenges, this review aims to contribute to the ongoing discourse on optimizing protein subunit vaccines for effective pandemic control.

COVID-19 Vaccines: Where Did We Stand at the End of 2023?

Vaccine development against SARS-CoV-2 has been highly successful in slowing down the COVID-19 pandemic. A wide spectrum of approaches including vaccines based on whole viruses, protein subunits and peptides, viral vectors, and nucleic acids has been developed in parallel. For all types of COVID-19 vaccines, good safety and efficacy have been obtained in both preclinical animal studies and in clinical trials in humans. Moreover, emergency use authorization has been granted for the major types of COVID-19 vaccines. Although high safety has been demonstrated, rare cases of severe adverse events have been detected after global mass vaccinations. Emerging SARS-CoV-2 variants possessing enhanced infectivity have affected vaccine protection efficacy requiring re-design and re-engineering of novel COVID-19 vaccine candidates. Furthermore, insight is given into preparedness against emerging SARS-CoV-2 variants.

Recombinant proteins production in Escherichia coli BL21 for vaccine applications: a cost estimation of potential industrial-scale production scenarios

Recent SARS-CoV-2 pandemic elevated research interest in microorganism-related diseases, and protective health application importance such as vaccination and immune promoter agents emerged. Among the production methods for proteins, recombinant technology is an efficient alternative and frequently preferred method. However, since the production and purification processes vary due to the protein nature, the effect of these differences on the cost remains ambiguous. In this study, brucellosis and its two important vaccine candidate proteins (rOmp25 and rEipB) with different properties were selected as models, and industrial-scale production processes were compared with the SuperPro Designer® for estimating the unit production cost. Simulation study showed raw material cost by roughly 60% was one of the barriers to lower-cost production and 52.5 and 559.8 $/g were estimated for rEipB and rOmp25, respectively.

Pre-Clinical Safety and Immunogenicity Study of a Coronavirus Protein-Based Subunit Vaccine for COVID-19

Creating an effective and safe vaccine is critical to fighting the coronavirus infection successfully. Several types of COVID-19 vaccines exist, including inactivated, live attenuated, recombinant, synthetic peptide, virus-like particle-based, DNA and mRNA-based, and sub-unit vaccines containing purified immunogenic viral proteins. However, the scale and speed at which COVID-19 is spreading demonstrate a global public demand for an effective prophylaxis that must be supplied more. The developed products promise a bright future for SARS-CoV-2 prevention; however, evidence of safety and immunogenicity is mandatory before any vaccine can be produced. In this paper, we report on the results of our work examining the safety, toxicity, immunizing dose choice, and immunogenicity of QazCoVac-P, a Kazakhstan-made sub-unit vaccine for COVID-19. First, we looked into the product's safety profile by assessing its pyrogenicity in vaccinated rabbit models and using the LAL (limulus amebocyte lysate) test. We examined the vaccine's acute and sub-chronic toxicity on BALB/c mice and rats. The vaccine did not cause clinically significant toxicity-related changes or symptoms in our toxicity experiments. Finally, we performed a double immunization of mice, ferrets, Syrian hamsters, and rhesus macaques (Macaca mulatta). We used ELISA to measure antibody titers with the maximum mean geometric titer of antibodies in the animals' blood sera totaling approximately 8 log2. The results of this and other studies warrant recommending the QazCoVac-P vaccine for clinical trials.

New-Onset Fulminant Type 1 Diabetes Following SARS-CoV-2 Protein Subunit Vaccine: A Case Report and Literature Review

The ravages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide have sped up the development of relevant vaccines, which is accompanied by public concerns over possible adverse effects. We report a rare case of a 39-year-old woman who suffered from severe hyperglycemia and ketoacidosis with normal hemoglobin A1c four days after SARS-CoV-2 protein subunit vaccine, which is consistent with the diagnosis of fulminant type 1 diabetes (FT1D). She received insulin therapy and recovered after 24 days from onset of the symptoms. This is the first case of new-onset FT1D after SARS-CoV-2 protein subunit vaccination and one of only six that developed after any form of SARS-CoV-2 vaccination. We hope to raise awareness of this potential adverse consequence and recommend careful monitoring after vaccination in patients even without a medical history of diabetes.

Modeling the Spread of COVID-19 with the Control of Mixed Vaccine Types during the Pandemic in Thailand

COVID-19 is a respiratory disease that can spread rapidly. Controlling the spread through vaccination is one of the measures for activating immunization that helps to reduce the number of infected people. Different types of vaccines are effective in preventing and alleviating the symptoms of the disease in different ways. In this study, a mathematical model, SVIHR, was developed to assess the behavior of disease transmission in Thailand by considering the vaccine efficacy of different vaccine types and the vaccination rate. The equilibrium points were investigated and the basic reproduction number R0 was calculated using a next-generation matrix to determine the stability of the equilibrium. We found that the disease-free equilibrium point was asymptotically stable if, and only if, R0<1, and the endemic equilibrium was asymptotically stable if, and only if, R0>1. The simulation results and the estimation of the parameters applied to the actual data in Thailand are reported. The sensitivity of parameters related to the basic reproduction number was compared with estimates of the effectiveness of pandemic controls. The simulations of different vaccine efficacies for different vaccine types were compared and the average mixing of vaccine types was reported to assess the vaccination policies. Finally, the trade-off between the vaccine efficacy and the vaccination rate was investigated, resulting in the essentiality of vaccine efficacy to restrict the spread of COVID-19.

Recombinant Protein Vaccines against Human Betacoronaviruses: Strategies, Approaches and Progress

Betacoronaviruses have already troubled humanity more than once. In 2002-2003 and 2012, the SARS-CoV and MERS-CoV, respectively, caused outbreaks of respiratory syndromes with a fatal outcome. The spread of the SARS-CoV-2 coronavirus has become a pandemic. These three coronaviruses belong to the genus Betacoronavirus and have a zoonotic origin. The emergence of new coronavirus infections in the future cannot be ruled out, and vaccination is the main way to prevent the spread of the infection. Previous experience in the development of vaccines against SARS and MERS has helped to develop a number of vaccines against SARS-CoV-2 in a fairly short time. Among them, there are quite a few recombinant protein vaccines, which seem to be very promising in terms of safety, minimization of side effects, storage and transportation conditions. The problem of developing a universal betacoronavirus vaccine is also still relevant. Here, we summarize the information on the designing of vaccines based on recombinant proteins against highly pathogenic human betacoronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2.

SARS-CoV-2 spike trimer vaccine expressed in Nicotiana benthamiana adjuvanted with Alum elicits protective immune responses in mice

The ongoing coronavirus disease 2019 (COVID-19) pandemic has spurred rapid development of vaccines as part of the public health response. However, the general strategy used to construct recombinant trimeric severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) proteins in mammalian cells is not completely adaptive to molecular farming. Therefore, we generated several constructs of recombinant S proteins for high expression in Nicotiana benthamiana. Intramuscular injection of N. benthamiana-expressed S_ct vaccine (NS_ct Vac) into Balb/c mice elicited both humoral and cellular immune responses, and booster doses increased neutralizing antibody titres. In human angiotensin-converting enzyme knock-in mice, two doses of NS_ct Vac induced anti-S and neutralizing antibodies, which cross-neutralized Alpha, Beta, Delta and Omicron variants. Survival rates after lethal challenge with SARS-CoV-2 were up to 80%, without significant body weight loss, and viral titres in lung tissue fell rapidly, with no infectious virus detectable at 7-day post-infection. Thus, plant-derived NS_ct Vac could be a candidate COVID-19 vaccine.

Evaluation of Immunogenicity and Clinical Protection of SARS-CoV-2 S1 and N Antigens in Syrian Golden Hamster

The novel coronavirus (SARS-CoV-2) epidemic continues to be a global public crisis affecting human health. Many research groups are developing different types of vaccines to suppress the spread of SARS-CoV-2, and some vaccines have entered phase III clinical trials and have been rapidly implemented. Whether multiple antigen matches are necessary to induce a better immune response remains unclear. To address this question, this study tested the immunogenicity and protective effects of a SARS-CoV-2 recombinant S and N peptide vaccine in the Syrian golden hamster model. This experiment was based on two immunization methods: intradermal and intramuscular administration. Immunized hamsters were challenged with live SARS-CoV-2 14 days after booster immunization. Clinical symptoms were observed daily, and the antibody titer and viral load in each tissue were detected. The results showed that immunization of golden hamsters with the SARS-CoV-2 structural protein S alone or in combination with the N protein through different routes induced antibody responses, whereas immunization with the N protein alone did not. However, although the immunized hamsters exhibited partial alleviation of clinical symptoms when challenged with the virus, neither vaccine effectively inhibited the proliferation and replication of the challenging virus. In addition, the pathological damage in the immunized hamsters was similar to that in the control hamsters. Interestingly, the neutralizing antibody levels of all groups including immunized and nonimmunized animals increased significantly after viral challenge. In conclusion, the immune response induced by the experimental S and N polypeptide vaccines had no significant ability to prevent viral infection and pathogenicity in golden hamsters.

Towards novel nano-based vaccine platforms for SARS-CoV-2 and its variants of concern: Advances, challenges and limitations

Vaccination is the most effective tool available for fighting the spread of COVID-19. Recently, emerging variants of SARS-CoV-2 have led to growing concerns about increased transmissibility and decreased vaccine effectiveness. Currently, many vaccines are approved for emergency use and more are under development. This review highlights the ongoing advances in the design and development of different nano-based vaccine platforms. The challenges, limitations, and ethical consideration imposed by these nanocarriers are also discussed. Further, the effectiveness of the leading vaccine candidates against all SARS-CoV-2 variants of concern are highlighted. The review also focuses on the possibility of using an alternative non-invasive routes of vaccine administration using micro and nanotechnologies to enhance vaccination compliance and coverage.

COVID-19 vaccination in patients receiving allergen immunotherapy (AIT) or biologicals-EAACI recommendations

Immune modulation is a key therapeutic approach for allergic diseases, asthma and autoimmunity. It can be achieved in an antigen-specific manner via allergen immunotherapy (AIT) or in an endotype-driven approach using biologicals that target the major pathways of the type 2 (T2) immune response: immunoglobulin (Ig)E, interleukin (IL)-5 and IL-4/IL-13 or non-type 2 response: anti-cytokine antibodies and B-cell depletion via anti-CD20. Coronavirus disease 2019 (COVID-19) vaccination provides an excellent opportunity to tackle the global pandemics and is currently being applied in an accelerated rhythm worldwide. The vaccine exerts its effects through immune modulation, induces and amplifies the response against the severe acute respiratory syndrome coronavirus (SARS-CoV-2). Thus, as there may be a discernible interference between these treatment modalities, recommendations on how they should be applied in sequence are expected. The European Academy of Allergy and Clinical Immunology (EAACI) assembled an expert panel under its Research and Outreach Committee (ROC). This expert panel evaluated the evidence and have formulated recommendations on the administration of COVID-19 vaccine in patients with allergic diseases and asthma receiving AIT or biologicals. The panel also formulated recommendations for COVID-19 vaccine in association with biologicals targeting the type 1 or type 3 immune response. In formulating recommendations, the panel evaluated the mechanisms of COVID-19 infection, of COVID-19 vaccine, of AIT and of biologicals and considered the data published for other anti-infectious vaccines administered concurrently with AIT or biologicals.

An overview of current drugs and prophylactic vaccines for coronavirus disease 2019 (COVID-19)

Designing and producing an effective vaccine is the best possible way to reduce the burden and spread of a disease. During the coronavirus disease 2019 (COVID-19) pandemic, many large pharmaceutical and biotechnology companies invested a great deal of time and money in trying to control and combat the disease. In this regard, due to the urgent need, many vaccines are now available earlier than scheduled. Based on their manufacturing technology, the vaccines available for COVID-19 (severe acute respiratory syndrome coronavirus 2 (SAR-CoV2)) infection can be classified into four platforms: RNA vaccines, adenovirus vector vaccines, subunit (protein-based) vaccines, and inactivated virus vaccines. Moreover, various drugs have been deemed to negatively affect the progression of the infection via various actions. However, adaptive variants of the SARS-CoV-2 genome can alter the pathogenic potential of the virus and increase the difficulty of both drug and vaccine development. In this review, along with drugs used in COVID-19 treatment, currently authorized COVID-19 vaccines as well as variants of the virus are described and evaluated, considering all platforms.

SARS-CoV-2 Virus-Like Particles Produced by a Single Recombinant Baculovirus Generate Anti-S Antibody and Protect against Variant Challenge

Coronavirus Disease 2019 (COVID-19), caused by infection with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has highlighted the need for the rapid generation of efficient vaccines for emerging disease. Virus-like particles, VLPs, are an established vaccine technology that produces virus-like mimics, based on expression of the structural proteins of a target virus. SARS-CoV-2 is a coronavirus where the basis of VLP formation has been shown to be the co-expression of the spike, membrane and envelope structural proteins. Here we describe the generation of SARS-CoV-2 VLPs by the co-expression of the salient structural proteins in insect cells using the established baculovirus expression system. VLPs were heterologous ~100 nm diameter enveloped particles with a distinct fringe that reacted strongly with SARS-CoV-2 convalescent sera. In a Syrian hamster challenge model, non-adjuvanted VLPs induced neutralizing antibodies to the VLP-associated Wuhan S protein and reduced virus shedding and protected against disease associated weight loss following a virulent challenge with SARS-CoV-2 (B.1.1.7 variant). Immunized animals showed reduced lung pathology and lower challenge virus replication than the non-immunized controls. Our data suggest SARS-CoV-2 VLPs offer an efficient vaccine that mitigates against virus load and prevents severe disease.

Self-Assembled Particles Combining SARS-CoV-2 RBD Protein and RBD DNA Vaccine Induce Synergistic Enhancement of the Humoral Response in Mice

Despite the fact that a range of vaccines against COVID-19 have already been created and are used for mass vaccination, the development of effective, safe, technological, and affordable vaccines continues. We have designed a vaccine that combines the recombinant protein and DNA vaccine approaches in a self-assembled particle. The receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 was conjugated to polyglucin:spermidine and mixed with DNA vaccine (pVAXrbd), which led to the formation of particles of combined coronavirus vaccine (CCV-RBD) that contain the DNA vaccine inside and RBD protein on the surface. CCV-RBD particles were characterized with gel filtration, electron microscopy, and biolayer interferometry. To investigate the immunogenicity of the combined vaccine and its components, mice were immunized with the DNA vaccine pVAXrbd or RBD protein as well as CCV-RBD particles. The highest antigen-specific IgG and neutralizing activity were induced by CCV-RBD, and the level of antibodies induced by DNA or RBD alone was significantly lower. The cellular immune response was detected only in the case of DNA or CCV-RBD vaccination. These results demonstrate that a combination of DNA vaccine and RBD protein in one construct synergistically increases the humoral response to RBD protein in mice.