Search Results (100)

Background/Objectives: Developing next-generation mRNA-based seasonal influenza vaccines remains challenging, primarily because of the relatively low immunogenicity of influenza B hemagglutinin (HA) antigens. We describe a systematic vaccine development strategy that combined vector and antigen design optimization. Methods: Novel untranslated region (UTR) sequences and a hybrid poly(A) tail were used to increase plasmid stability and mRNA expression. Fusion proteins containing HA antigens linked by T4 foldon domains were engineered to enhance the immune responses against influenza B HA antigens and to permit the expression of multiple HA ectodomains from a single mRNA species. The vaccine performance was verified in a traditional encapsulated lipid nanoparticle (LNP) formulation that requires long-term storage at temperatures below −15 °C as well as in a proprietary thermo-stable LNP formulation developed for the long-term storage of the mRNA vaccine at 2–8 °C. Results: In preclinical studies, our next-generation seasonal influenza vaccine tested alone or as a combination influenza/COVID-19 mRNA vaccine elicited hemagglutination inhibition (HAI) titers significantly higher than Fluzone HD, a commercial inactivated influenza vaccine, across all 2024/2025 seasonal influenza strains, including the B/Victoria lineage strain. At the same time, the combination mRNA vaccine demonstrated superior neutralizing antibody titers to 2023/2024 Spikevax, a commercial COVID-19 comparator mRNA vaccine. Conclusions: Our data demonstrate that the multimerization of antigens expressed as complex fusion proteins is a powerful antigen design approach that may be broadly applied toward mRNA vaccine development. Full article

Background: SARS-CoV-2 was the causing agent of the COVID-19 pandemic, which resulted in millions of deaths worldwide and massive economic losses. Although there are already several vaccines licensed, as novel variants develop, understanding the immune response induced by vaccination and natural infection is key for the development of future vaccines. Methods: In this study, we have used flow cytometry and next-generation sequencing to assess the longitudinal CD8⁺ T-cell response against natural infection and vaccination in convalescent and vaccinated individuals, from early activation to immune memory establishment. Moreover, we have characterized the T-cell receptor clonality and diversity at different stages post-infection and post-vaccination. Results: We have found no significant differences in CD8⁺ T-cell activation during the first three weeks post-infection compared to the first three weeks after first vaccination. Conversely, natural infection resulted in sustained high levels of T-cell activation at four weeks post-infection, a point in which we observed a decline in T-cell activation post-vaccination despite boosting with a second vaccination shot. Moreover, additional vaccination did not result in enhanced T-cell activation. Of note, we have observed variations in the memory subset structure at every stage of disease and vaccination. Overall, both infection and immunization induced a highly diverse T-cell receptor repertoire, which was observed both between study groups and between patients inside a given group. Conclusions: These data contribute to expand our knowledge about the immune response to SARS-CoV-2 infection and vaccination and call for additional strategies to enhance T-cell responses by booster immunization. Full article

Adenoviral (AdV) vector-based vaccines employing the human AdV (HAdV) and chimpanzee AdV (ChAdV) vector platforms played a crucial role in combating the COVID-19 pandemic. However, the widespread use of these platforms, the prevalence of various HAdV types, and the resulting preexisting immunity have significantly impacted the vaccines utilizing these vector platforms. Considering these challenges, the bovine AdV type 3 (BAdV-3) vector system has emerged as a versatile and innovative platform for developing next-generation vaccines against infectious diseases. Inherent attributes like a high transduction efficiency, large transgene insertion capacity, broad tissue tropism, and robust induction of innate immunity add significant value to the BAdV vector platform for vaccine design. BAdV-3 vectors effectively elude HAdV-specific preexisting humoral and cellular immune responses. Additionally, BAdV-3 is low in pathogenicity for its host and is anticipated to be safe as a vaccine platform. This systematic review provides an overview of the development of BAdV-3 as a vaccine delivery platform and its application in designing vaccines for infectious agents of human and veterinary importance. Full article

SARS-CoV-2 high transmission and genomic mutations result in the emergence of new variants that impact COVID-19 vaccine efficacy and virus transmission by evading the host immune system. Wastewater-based epidemiology is an effective approach to monitor SARS-CoV-2 variants circulation in the population but is a challenge due to the presence of reaction inhibitors and the low concentrations of SARS-CoV-2 in this environment. Here, we aim to improve SARS-CoV-2 variant detection in wastewater by employing nested PCR followed by next-generation sequencing (NGS) of small amplicons of the S gene. Eight SARS-CoV-2 wastewater samples from Alegria Wastewater Treatment Plant, in Rio de Janeiro, Brazil, were collected monthly from February to September 2021. Samples were submitted to virus concentration, RNA extraction and nested PCR followed by NGS. The small amplicons were used to prepare libraries for sequencing without the need to perform any fragmentation step. We identified and calculated the frequencies of 29 mutations matching the Alpha, Beta, Gamma, Delta, Omicron, and P.2 variants. Omicron matching-mutations were detected before the lineage was classified as a variant of concern. SARS-CoV-2 wastewater sequences clustered with SARS-CoV-2 variants detected in clinical samples that circulated in 2021 in Rio de Janeiro. We show that sequencing of selected small amplicons of SARS-CoV-2 S gene allows the identification of SARS-CoV-2 variants matching mutations and their frequencies’ calculation. This approach may be expanded using customizing primers for additional genomic regions, in order to differentiate current variants. Approaches that allow us to learn how variants emerge and how they relate to clinical outcomes are crucial for our understanding of the dynamics of virus variants circulation, providing valuable data for public health management. Full article

Vaccination has been instrumental in curbing the transmission of SARS-CoV-2 and mitigating the severity of clinical manifestations associated with COVID-19. Numerous COVID-19 vaccines have been developed to this effect, including BioNTech-Pfizer and Moderna’s mRNA vaccines, as well as adenovirus vector-based vaccines such as Oxford–AstraZeneca. However, the emergence of new variants and subvariants of SARS-CoV-2, characterized by enhanced transmissibility and immune evasion, poses significant challenges to the efficacy of current vaccination strategies. In this review, we aim to comprehensively outline the landscape of emerging SARS-CoV-2 variants of concern (VOCs) and sub-lineages that have recently surfaced in the post-pandemic years. We assess the effectiveness of existing vaccines, including their booster doses, against these emerging variants and subvariants, such as BA.2-derived sub-lineages, XBB sub-lineages, and BA.2.86 (Pirola). Furthermore, we discuss the latest advancements in vaccine technology, including multivalent and pan-coronavirus approaches, along with the development of several next-generation coronavirus vaccines, such as exosome-based, virus-like particle (VLP), mucosal, and nanomaterial-based vaccines. Finally, we highlight the key challenges and critical areas for future research to address the evolving threat of SARS-CoV-2 subvariants and to develop strategies for combating the emergence of new viral threats, thereby improving preparedness for future pandemics. Full article

This review systematically revises adenovirus (Ad) biology, vector structure, immune responses, and currently available Ad vector COVID-19 vaccines. It analyzes the challenges associated with the Ad vector-based vaccines, including preexisting vector immunity and other side effects. Moreover, this review explores novel and innovative strategies to overcome these constraints for developing next-generation vaccines for broad protection to cover emerging SARS-CoV-2 variants. The future refinement of Ad vaccine platforms will be pivotal in achieving durable immunity against emerging variants for global preparedness. Full article

Background: Lipid nanoparticles (LNPs) have proven effective in delivering RNA-based modalities. Rapid approval of the COVID-19 vaccines highlights the promise of LNPs as a delivery platform for nucleic acid-based therapies and vaccines. Nevertheless, improved LNP designs are needed to advance next-generation vaccines and other gene therapies toward greater clinical success. Lipid components and LNP formulation excipients play a central role in biodistribution, immunogenicity, and stability. Therefore, it is important to understand, identify, and assess the appropriate lipid components for developing a safe and effective formulation. Herein, this study focused on developing a novel Polysorbate-80 (PS-80)-based LNP. We hypothesized that substituting conventional linear PEG-lipids with PS-80, a widely used, biocompatible injectable surfactant featuring a branched PEG-like structure, may change the LNPs biodistribution pattern and enhance long-term stability. By leveraging PS-80’s unique structural properties, this study aimed to develop an mRNA-LNP platform with improved extrahepatic delivery and robust freeze/thaw tolerance. Methods: We employed a stepwise optimization to establish both the lipid composition and formulation buffer to yield a stable, high-performing PS-80-based SARS-CoV-2 mRNA-LNP (SC2-PS80 LNP). We compared phosphate- versus tris-based buffers for long-term stability, examined multiple lipid ratios, and evaluated the impact of incorporating PS-80 (a branched PEG-lipid) on in vivo biodistribution. Various analytical assays were performed to assess particle size, encapsulation efficiency, mRNA purity, and in vitro potency of the developed formulation and a humanized mouse model was used to measure its immunogenicity over six months of storage at −80 °C. Results: Replacing the standard 1,2-dimyristoyl-rac-glycero-3-methoxy polyethylene glycol-2000 (PEG-DMG) lipid with PS-80 increased spleen-specific expression of the mRNA-LNPs after intramuscular injection. Formulating in a tris-sucrose-salt (TSS) buffer preserved the LNP’s physicochemical properties and in vitro potency over six months at −80 °C, whereas a conventional PBS-sucrose (PSS) buffer was less protective under frozen conditions. Notably, TSS-based SC2-PS80 LNPs elicited potent humoral immunity in mice, including high anti-spike IgG titers and robust pseudovirus neutralization, comparable to freshly prepared formulations. Conclusions: A PS-80-based mRNA-LNP platform formulated in TSS buffer confers improved extrahepatic delivery, long-term frozen stability, and strong immunogenicity against SARS-CoV-2 following six months. These findings offer a promising pathway for the design of next-generation mRNA vaccines and therapeutics with enhanced stability and clinical potential. Full article

Viral infectious diseases pose a serious threat to global public health due to their high transmissibility, rapid mutation rates, and limited treatment options. Recent outbreaks of diseases such as plague, monkeypox, avian influenza, and coronavirus disease 2019 (COVID-19) have underscored the urgent need for efficient diagnostic and surveillance technologies. Focusing on viral infectious diseases that seriously threaten human health, this review summarizes and analyzes detection techniques from the perspective of combining viral surveillance and prevention advice, and discusses applications in improving diagnostic sensitivity and specificity. One of the major innovations of this review is the systematic integration of advanced biorecognition and detection technologies, such as bionanosensors, rapid detection test strips, and microfluidic platforms, along with the exploration of artificial intelligence in virus detection. These technologies address the limitations of traditional methods and enable the real-time monitoring and early warning of viral outbreaks. By analyzing the application of these technologies in the detection of pathogens, new insights are provided for the development of next-generation diagnostic tools to address emerging and re-emerging viral threats. In addition, we analyze the current progress of developed vaccines, combining virus surveillance with vaccine research to provide new ideas for future viral disease prevention and control and vaccine development, and call for global attention and the development of new disease prevention and detection technologies. Full article

Background: Rabies is a preventable zoonotic disease caused by the rabies virus (RABV) with a high mortality rate. Most vaccines on the market or under development have issues, such as low single-dose neutralization titer, complex processes, and high costs. During the COVID-19 pandemic, the successful development of mRNA vaccines opened up a new avenue for preventive vaccines. As a new technology, mRNA has higher scalability. Methods: In this study, we designed an mRNA encoding the RV-G protein, encapsulated by our own muscle-targeting lipid nanoparticles (LNPs), and evaluated the expression of the RV-G protein in vitro, its immunogenicity, and its protection against virus infection in vivo. Results: The results show that RV-G mRNA was significantly expressed in vitro. High Virus-IgG binding titers and virus-neutralizing antibody titers (VNT) were induced by immunization with RV-G mRNA-LNP. Additionally, our results showed that the RV-G mRNA vaccine is better than commercially available vaccines in mice. Conclusions: Our research highlights the potential of the mRNA-LNP platform in developing next-generation rabies vaccines. Full article

Background: During the COVID-19 pandemic, we continuously monitored the epidemiology of influenza virus among pediatric patients from January 2021 to December 2023 in Hainan Island, China. Methods: In this study, we collected 54,974 nasopharyngeal swab samples for influenza A Virus (IAV) testing and 53,151 samples for influenza B Virus (IBV) testing from pediatric outpatients. Additionally, we also collected 19,687 nasopharyngeal swab samples from pediatric inpatients for IAV and IBV testing. Outpatient samples were screened for influenza viruses (IVs) infection by the colloidal gold method. Targeted Next-Generation Sequencing (tNGS) was used to detect influenza virus infections in inpatients. Influenza virus types were identified by analyzing the HA/NA partial regions. Results: The findings revealed a significant decrease in the infection rate of IBV over the specified period, while the infection rate of IAV exhibited a rising trend. Additionally, B/Victoria lineage was the dominant epidemic strain in 2021, while the epidemic strains in 2022 and 2023 underwent a dynamic transformation from A/H3N2 to A/H1N1. Phylogenetic analysis revealed close relationships among the circulating strains. Nonetheless, because the sample size is limited, additional research is required. Conclusions: Our findings suggest that the predominant types of influenza viruses in the pediatric population are undergoing dynamic changes, influenced by the implementation and relaxation of non-pharmaceutical intervention measures. These findings highlight the need for adaptive influenza vaccination and containment strategies, particularly in tropical regions like Hainan, where climate and public health policies significantly impact viral transmission patterns. The insights gained from this study could inform more effective public health strategies in similar regions to mitigate the impact of influenza outbreaks in the future. Full article

Background: Next-generation vaccines against coronavirus disease 2019 (COVID-19) focus on inducing a long-lasting immune response against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its emerging variants. To achieve this, antigens other than spike proteins have been proposed, and different platforms have been evaluated. Nucleic acid-based vaccines are fundamental for this process. Preclinical data have shown that the SARS-CoV-2 nucleocapsid protein induces a protective cellular immune response, and when combined with the spike protein, the resulting humoral and cellular immune responses are effective against some SARS-CoV-2 variants. Methods: We designed a DNA vaccine against the spike and nucleocapsid proteins of SARS-CoV-2 to generate fusion proteins based on the Delta and Omicron B.5 strains. The most immunogenic regions of the spike and nucleocapsid proteins of the Delta and Omicron B strains were selected using bioinformatics. The nucleotide sequences were cloned into pcDNA3.1, and named pcDNA3.1/D-S1, pcDNA3.1/D-S1N, and pcDNA3.1/O-SN. The immunogenicity of the generated fusion proteins was evaluated by analyzing the humoral and cellular responses elicited after the immunization of BALB/c mice. Results: DNA immunization induced antibody production, neutralization activity, and IFN-γ production. The inclusion of the nucleocapsid regions in the plasmid greatly enhanced the immune response. Moreover, cross-reactions with the variants of interest were confirmed. Conclusions: Plasmids-encoding fusion proteins combining the most immunogenic regions of the spike and nucleocapsid proteins present a promising strategy for designing new and effective vaccines against SARS-CoV-2. Full article

The COVID-19 pandemic has posed a significant threat to global health systems, with extensive impacts across many sectors of society. The pandemic has been responsible for millions of deaths worldwide since its first identification in late 2019. Several actions have been taken to prevent the disease, including the unprecedented fast development and global vaccination campaigns, which were pivotal in reducing symptoms and deaths. Given the impact of the pandemic, the continuous changes of the virus, and present vaccine technologies, this review analyzes how, so far, we have met the challenge posed by the emergence of new variants and discusses how next-generation pan-coronavirus vaccines, with enhanced longevity and breadth of immune responses, may be tackled with alternative administration routes and antigen delivery platforms. By addressing these critical aspects, this review aims to contribute to the ongoing efforts to achieve long-term control of COVID-19, stimulating the discussion and work on next-generation vaccines capable of facing future waves of infection. Full article

The COVID-19 pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), is in its sixth year and is being maintained by the inability of current spike-alone-based COVID-19 vaccines to prevent transmission leading to the continuous emergence of variants and sub-variants of concern (VOCs). This underscores the critical need for next-generation broad-spectrum pan-Coronavirus vaccines (pan-CoV vaccine) to break this cycle and end the pandemic. The development of a pan-CoV vaccine offering protection against a wide array of VOCs requires two key elements: (1) identifying protective antigens that are highly conserved between passed, current, and future VOCs; and (2) developing a safe and efficient antigen delivery system for induction of broad-based and long-lasting B- and T-cell immunity. This review will (1) present the current state of antigen delivery platforms involving a multifaceted approach, including bioinformatics, molecular and structural biology, immunology, and advanced computational methods; (2) discuss the challenges facing the development of safe and effective antigen delivery platforms; and (3) highlight the potential of nucleoside-modified mRNA encapsulated in lipid nanoparticles (LNP) as the platform that is well suited to the needs of a next-generation pan-CoV vaccine, such as the ability to induce broad-based immunity and amenable to large-scale manufacturing to safely provide durable protective immunity against current and future Coronavirus threats. Full article

Although the Coronavirus disease 2019 (COVID-19) pandemic has ended, there are still many important lessons we can learn, as the pandemic profoundly affected every area of laboratory practice. During the pandemic, extensive changes to laboratory staffing had to be implemented, as many healthcare institutions required regular screening of all healthcare staff. Several studies examined the effectiveness of different screening regimens and concluded that repeated testing, even with lower sensitivity tests, could rival the performance of gold-standard RT-PCR testing in the detection of new cases. Many assay evaluations were performed both in the earlier and later periods of the pandemic. They included both nucleocapsid/spike antibodies and automated antigen assays. Early in the pandemic, it was generally agreed that the initial nucleocapsid antibody assays had poor sensitivity when used before 14 days of disease onset, with total or IgG antibodies being preferred over the use of IgM. Spike antibody assays gradually replaced nucleocapsid antibody assays, as most people were vaccinated. Spike antibodies tracked the rise in antibodies after vaccination with mRNA vaccines and became invaluable in the assessment of vaccine response. Studies demonstrated robust antibody secretion with each vaccine dose and could last for several months post-vaccination. When antigen testing was introduced, they became effective tools to identify affected patients when used serially or in an orthogonal fashion with RT-PCR testing. Despite the numerous findings during the pandemic period, research in COVID-19 has slowed. To this day it is difficult to identify a true neutralizing antibody test for the virus. An appropriate antibody level that would confer protective immunity against the plethora of new variants remains elusive. We hope that a summary of events during the pandemic could provide important insights to consider in planning for the next viral pandemic. Full article

Although global life expectancy has increased over the past 20 years due to advancements in managing infectious diseases, one-fifth of people still die from infections. In response to this ongoing threat, significant efforts are underway to develop vaccines and antimicrobial agents. However, pathogens evolve resistance mechanisms, complicating their control. The COVID-19 pandemic has underscored the limitations of focusing solely on the pathogen-killing strategies of immunology and microbiology to address complex, multisystemic infectious diseases. This highlights the urgent need for practical advancements, such as microbiome therapeutics, that address these limitations while complementing traditional approaches. Our review emphasizes key outcomes in the field, including evidence of probiotics reducing disease severity and insights into host-microbiome crosstalk that have informed novel therapeutic strategies. These findings underscore the potential of microbiome-based interventions to promote physiological function alongside existing strategies aimed at enhancing host immune responses and pathogen destruction. This narrative review explores microbiome therapeutics as next-generation treatments for infectious diseases, focusing on the application of probiotics and their role in host-microbiome interactions. While offering a novel perspective grounded in a cooperative defense system, this review also addresses the practical challenges and limitations in translating these advancements into clinical settings. Full article