Development of mRNA vaccines against respiratory syncytial virus (RSV)

Epidemiological and pathological characterization of acute respiratory infections

This research comprehensively investigates the epidemiological features and pathogen profile of acute respiratory infections (ARI) in Shihezi City, Xinjiang. A pivotal aspect of this study is the construction of a Bayes discriminant function for principal pathogen infections. This innovative methodology aims to furnish a robust scientific basis for the prevention and clinical management of ARI, potentially guiding more effective strategies in both public health and clinical settings. We compiled and examined data from January 2020 to June 2023, pertaining to patients admitted with acute respiratory infections at the First Affiliated Hospital of Shihezi University. This investigation focused on discerning patterns in epidemiology and pathogen etiology. Among 2110 cases of acute respiratory infections (ARI), 1736 underwent pathogenetic testing. Of these, 595 cases tested positive for at least one pathogen, marking a positivity rate of 34.27%. Viral detections, at a rate of 27.47%, were notably higher than bacterial detections, which stood at 6.51%. The most prevalent viruses identified were Human respiratory syncytial virus (hRSV), Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and Human adenovirus (HAdV), while the dominant bacterial pathogens included Klebsiella pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Co-infections were observed in 76 cases, accounting for 12.77% of positive diagnoses, predominantly involving hRSV in conjunction with other pathogens. In cases of acute bronchiolitis, hRSV was the most frequent pathogen, contributing to 23.10% of such cases. Similarly, in severe pneumonia cases, SARS-CoV-2 was predominant, accounting for 25.4% of these infections. The group with bacterial positivity exhibited elevated levels of C-reactive protein (CRP, 19.17 mg/L) and neutrophilic granulocyte percentage (NE%, 54.7%). The Bayes discriminant function demonstrated an initial validation accuracy of 74.9% and a cross-validation accuracy of 63.7%. The study underscores that hRSV, SARS-CoV-2, and HAdV are the primary pathogens in acute respiratory infections in the Shihezi region. Pathogen susceptibility exhibits variation across different age groups, with a higher pathogen detection rate in children compared to adults. The Bayes discriminant function shows significant promise in the classification and diagnosis of major pathogenic infections.

Both chebulagic acid and punicalagin inhibit respiratory syncytial virus entry via multi-targeting glycoprotein and fusion protein

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections, with no currently available small-molecule drugs that are both safe and effective. A major obstacle in antiviral drug development is the rapid emergence of drug-resistant viral strains. Targeting multiple viral compounds may help mitigate the development of resistance. Herein, we conducted a drug screening using the Antiviral Traditional Chinese Medicine Active Compound Library, aiming to identify compounds that simultaneously target the RSV fusion (F) protein, glycoprotein (G), and the host heparan sulfate proteoglycans (HSPGs). From this screening, 10 candidate compounds were identified for their ability to interact with all three targets. Among these 10 candidates, chebulagic acid (CHLA) and punicalagin (PUG) demonstrated the most potent inhibition of RSV replication. In vitro dose-response assays confirmed the antiviral efficacy of CHLA (IC50: 0.07864 µM) and PUG (IC50: 0.08065 µM). Further experiments revealed both CHLA and PUG disrupt RSV attachment and membrane fusion by targeting the RSV-F and G proteins, rather than HSPG. Notably, CHLA and PUG were found to bind to the CX3C motif of the RSV-G protein, with docking assays predicting their binding sites at cysteines 176 and 182. Additionally, CHLA enhanced the conformational stability of the RSV-F protein before fusion. In an in vivo study, both CHLA and PUG were shown to alleviate RSV-induced pulmonary pathology by reducing viral titers, mitigating lung injury, and suppressing the inflammatory responses in the lungs. Our findings suggest that CHLA and PUG hold potential as therapeutic agents for RSV infection.IMPORTANCEA significant challenge in developing anti-respiratory syncytial virus (RSV) agents is the rapid emergence of resistant viral strains. Designing drugs that target multiple viral components can effectively reduce the likelihood of developing resistant strains. In this study, we screened compounds from the Antiviral Traditional Chinese Medicine Active Compound Library, aiming to simultaneously targe the RSV fusion (F) protein, glycoprotein (G), and host heparan sulfate proteoglycans (HSPGs). Our findings revealed that chebulagic acid (CHLA) and punicalagin (PUG) significantly inhibited RSV replication both in vitro and in vivo and interacted with all three targets. Both CHLA and PUG were able to disrupt RSV attachment and membrane fusion. Mechanistically, CHLA and PUG were found to bind to the CX3C motif of the RSV-G protein, with CHLA also enhancing the conformational stability of the RSV-F protein before fusion. In conclusion, our study suggests that CHLA and PUG hold promise as therapeutic agents against RSV infection.

Vaccine and therapeutic agents against the respiratory syncytial virus: resolved and unresolved issue

Respiratory syncytial virus (RSV) is a predominant pathogen responsible for respiratory tract infections among infants, the elderly, and immunocompromised individuals. In recent years, significant progress has been made in innovative vaccines and therapeutic agents targeting RSV. Nevertheless, numerous challenges and bottlenecks persist in the prevention and treatment of RSV infections. This review will provide an overview of the resolved and unresolved issues surrounding the development of vaccines and therapeutic agents against RSV. As of September 2024, three RSV vaccines against acute lower respiratory infections (ALRI) have been approved globally. Additionally, there have been notable progress in the realm of passive immunoprophylactic antibodies, with the monoclonal antibody nirsevimab receiving regulatory approval for the prevention of RSV infections in infants. Furthermore, a variety of RSV therapeutic agents are currently under clinical investigation, with the potential to yield breakthrough advancements in the foreseeable future. This review delineates the advancements and challenges faced in vaccines and therapeutic agents targeting RSV. It aims to provide insights that will guide the development of effective preventive and control measures for RSV.

Biology of human respiratory syncytial virus: Current perspectives in immune response and mechanisms against the virus

Human respiratory syncytial virus (hRSV) remains a leading cause of morbidity and mortality in infants, young children, and older adults. hRSV infection's limited treatment and vaccine options significantly increase bronchiolitis' morbidity rates. The severity and outcome of viral infection hinge on the innate immune response. Developing vaccines and identifying therapeutic interventions suitable for young children, older adults, and pregnant women relies on comprehending the molecular mechanisms of viral PAMP recognition, genetic factors of the inflammatory response, and antiviral defense. This review covers fundamental elements of hRSV biology, diagnosis, pathogenesis, and the immune response, highlighting prospective options for vaccine development.

RNA Modifications in Pathogenic Viruses: Existence, Mechanism, and Impacts

RNA modification is a key posttranscriptional process playing various biological roles, and one which has been reported to exist extensively in cellular RNAs. Interestingly, recent studies have shown that viral RNAs also contain a variety of RNA modifications, which are regulated dynamically by host modification machinery and play critical roles in different stages of the viral life cycle. In this review, we summarize the reports of four typical modifications reported on viral RNAs, including N6-methyladenosine (m6A), 5-methylcytosine (m5C), N4-acetylcytosine (ac4C), and N1-methyladenosine (m1A), describe the molecular mechanisms of these modification processes, and illustrate their impacts on viral replication, pathogenicity, and innate immune responses. Notably, we find that RNA modifications in different viruses share some common features and mechanisms in their generation, regulation, and function, highlighting the potential for viral RNA modifications and the related host machinery to serve as the targets or bases for the development of antiviral therapeutics and vaccines.

Progress and prospects of mRNA-based drugs in pre-clinical and clinical applications

In the last decade, messenger ribonucleic acid (mRNA)-based drugs have gained great interest in both immunotherapy and non-immunogenic applications. This surge in interest can be largely attributed to the demonstration of distinct advantages offered by various mRNA molecules, alongside the rapid advancements in nucleic acid delivery systems. It is noteworthy that the immunogenicity of mRNA drugs presents a double-edged sword. In the context of immunotherapy, extra supplementation of adjuvant is generally required for induction of robust immune responses. Conversely, in non-immunotherapeutic scenarios, immune activation is unwanted considering the host tolerability and high expression demand for mRNA-encoded functional proteins. Herein, mainly focused on the linear non-replicating mRNA, we overview the preclinical and clinical progress and prospects of mRNA medicines encompassing vaccines and other therapeutics. We also highlight the importance of focusing on the host-specific variations, including age, gender, pathological condition, and concurrent medication of individual patient, for maximized efficacy and safety upon mRNA administration. Furthermore, we deliberate on the potential challenges that mRNA drugs may encounter in the realm of disease treatment, the current endeavors of improvement, as well as the application prospects for future advancements. Overall, this review aims to present a comprehensive understanding of mRNA-based therapies while illuminating the prospective development and clinical application of mRNA drugs.

Advancement in the development of mRNA-based vaccines for respiratory viruses

Acute respiratory infections are the leading cause of death and illness in children under 5 years old and represent a significant burden in older adults. Primarily caused by viruses infecting the lower respiratory tract, symptoms include cough, congestion, and low-grade fever, potentially leading to bronchiolitis and pneumonia. Messenger ribonucleic acid (mRNA)-based vaccines are biopharmaceutical formulations that employ mRNA molecules to induce specific immune responses, facilitating the expression of viral or bacterial antigens and promoting immunization against infectious diseases. Notably, this technology had significant relevance during the COVID-19 pandemic, as these formulations helped to limit SARS-CoV-2 virus infections, hospitalizations, and deaths. Importantly, mRNA vaccines promise to be implemented as new alternatives for fighting other respiratory viruses, such as influenza, human respiratory syncytial virus, and human metapneumovirus. This review article analyzes mRNA-based vaccines' main contributions, perspectives, challenges, and implications against respiratory viruses.

Induction of neutralizing antibody responses by AAV5-based vaccine for respiratory syncytial virus in mice

Introduction

Respiratory Syncytial Virus (RSV) is a significant cause of respiratory illnesses worldwide, particularly in infants and elderly individuals. Despite the burden RSV imposes, effective preventive measures are limited. The research application of adeno-associated virus (AAV) in vaccine platforms has been expanding, and its potential in prevention and treatment has garnered much attention.

Methods

In this study, we explored the potential application of a recombinant adeno-associated virus 5 (rAAV5) vector-based RSV vaccine, focusing on the expression of the pre-fusion (Pre-F) protein structure. Through intramuscular immunization in mice. The immunogenicity of the vaccine was evaluated in Balb/c mice immunized intramuscularly and intranasal, respectively.

Results

The rAAV5-RSV-Fm vaccine demonstrated positive humoral and induced antibody titers against RSV strains A and B for up to 120 days post-immunization. Notably, intranasal administration also elicited protective antibodies. Characterization studies confirmed the ability of the vac-cine to express the Pre-F protein and its superior immunogenicity compared to that of full-length F protein.

Conclusion

These findings underscore the potential application of rAAV5 vector platforms in RSV vaccine development and further investigation into their protective efficacy is warranted.

Innovative biomarkers TCN2 and LY6E can significantly inhibit respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) is a prominent etiological agent of lower respiratory tract infections in children, responsible for approximately 80% of cases of pediatric bronchiolitis and 50% of cases of infant pneumonia. Despite notable progress in the diagnosis and management of pediatric RSV infection, the current biomarkers for early-stage detection remain insufficient to meet clinical needs. Therefore, the development of more effective biomarkers for early-stage pediatric respiratory syncytial virus infection (EPR) is imperative.

METHODS

The datasets used in this study were derived from the Gene Expression Omnibus (GEO) database. We used GSE188427 dataset as the training set to screen for biomarkers. Biomarkers of EPR were screened by Weighted Gene Co-expression Network Analysis (WGCNA), three machine-learning algorithms (LASSO regression, Random Forest, XGBoost), and other comprehensive bioinformatics analysis techniques. To evaluate the diagnostic value of these biomarkers, multiple external and internal datasets were employed as validation sets. Next, an examination was performed to investigate the relationship between the screened biomarkers and the infiltration of immune cells. Furthermore, an investigation was carried out to identify potential small molecule compounds that interact with selected diagnostic markers. Finally, we confirmed that the expression levels of the selected biomarkers exhibited a significant increase following RSV infection, and they were further identified as having antiviral properties.

RESULTS

The study found that lymphocyte antigen 6E (LY6E) and Transcobalamin-2 (TCN2) are two biomarkers with diagnostic significance in EPR. Analysis of immune cell infiltration showed that they were associated with activation of multiple immune cells. Furthermore, our analysis demonstrated that small molecules, 3'-azido-3'-deoxythymine, methotrexate, and theophylline, have the potential to bind to TCN2 and exhibit antiviral properties. These compounds may serve as promising therapeutic agents for the management of pediatric RSV infections. Additionally, our data revealed an upregulation of LY6E and TCN2 expression in PBMCs from patients with RSV infection. ROC analysis indicated that LY6E and TCN2 possessed diagnostic value for RSV infection. Finally, we confirmed that LY6E and TCN2 expression increased after RSV infection and further inhibited RSV infection in A549 and BEAS-2B cell lines. Importantly, based on TCN2, our findings revealed the antiviral properties of a potentially efficacious compound, vitamin B12.

CONCLUSION

LY6E and TCN2 are potential peripheral blood diagnostic biomarkers for pediatric RSV infection. LY6E and TCN2 inhibit RSV infection, indicating that LY6E and TCN2 are potential therapeutic target for RSV infection.

Global progress in clinical research on human respiratory syncytial virus vaccines

Human respiratory syncytial virus (hRSV) not only affects newborns but also older adults, contributing to a substantial worldwide burden of disease. However, only three approved hRSV vaccines remain commercially available to date. The development of a safe, practical and broad-spectrum vaccine suitable for all age groups remains extremely challenging. Using five different approaches-live-attenuated, recombinant-vector, subunit, particle-based, and mRNA-nearly 30 hRSV vaccine candidates are currently conducting clinical trials worldwide; moreover, > 30 vaccines are under preclinical evaluation. This review presents a comprehensive overview of these hRSV vaccines along with prospects for the development of infectious disease vaccines in the post-COVID-19 pandemic era.

Cracking the Codes behind Cancer Cells' Immune Evasion

Immune evasion is a key phenomenon in understanding tumor recurrence, metastasis, and other critical steps in tumor progression. The tumor microenvironment (TME) is in constant flux due to the tumor's ability to release signals that affect it, while immune cells within it can impact cancer cell behavior. Cancer cells undergo several changes, which can change the enrichment of different immune cells and modulate the activity of existing immune cells in the tumor microenvironment. Cancer cells can evade immune surveillance by downregulating antigen presentation or expressing immune checkpoint molecules. High levels of tumor-infiltrating lymphocytes (TILs) correlate with better outcomes, and robust immune responses can control tumor growth. On the contrary, increased enrichment of Tregs, myeloid-derived suppressor cells, and M2-like anti-inflammatory macrophages can hinder effective immune surveillance and predict poor prognosis. Overall, understanding these immune evasion mechanisms guides therapeutic strategies. Researchers aim to modulate the TME to enhance immune surveillance and improve patient outcomes. In this review article, we strive to summarize the composition of the tumor immune microenvironment, factors affecting the tumor immune microenvironment (TIME), and different therapeutic modalities targeting the immune cells. This review is a first-hand reference to understand the basics of immune surveillance and immune evasion.

Towards broad-spectrum protection: the development and challenges of combined respiratory virus vaccines

In the post-COVID-19 era, the co-circulation of respiratory viruses, including influenza, SARS-CoV-2, and respiratory syncytial virus (RSV), continues to have significant health impacts and presents ongoing public health challenges. Vaccination remains the most effective measure for preventing viral infections. To address the concurrent circulation of these respiratory viruses, extensive efforts have been dedicated to the development of combined vaccines. These vaccines utilize a range of platforms, including mRNA-based vaccines, viral vector vaccines, and subunit vaccines, providing opportunities in addressing multiple pathogens at once. This review delves into the major advancements in the field of combined vaccine research, underscoring the strategic use of various platforms to tackle the simultaneous circulation of respiratory viruses effectively.

Emodin inhibits respiratory syncytial virus entry by interactions with fusion protein

Introduction

Respiratory syncytial virus (RSV) fusion (F) protein is essential for facilitating virus entry into host cells, providing a hopeful path for combating viral diseases. However, F protein inhibitors can rapidly select for viral resistance. Thus, discovering new inhibitors of F-protein is necessary to enrich the RSV drug development pipeline.

Methods

In this study, we screen 25 bioactive compounds from Chinese herbal medicines that exhibit a strong binding to the RSV-F protein using surface plasmon resonance.

Results

After screening, we found emodin could strongly bind to RSV-F protein, and could effectively curb RSV infection. Further investigations certificated that emodin specifically disrupts the attachment and internalization phases of RSV infection by targeting the RSV-F protein. In vivo studies with mice infected with RSV demonstrated that emodin effectively reduces lung pathology. This therapeutic effect is attributed to emodin's capacity to diminish pro-inflammatory cytokine production and reduce viral load in the lungs.

Discussion

In conclusion, our findings provide initial insights into the mechanism by which emodin counters RSV infection via engagement with the RSV-F protein, establishing it as a viable contender for the development of novel therapeutic agents aimed at RSV.

What U.S. Obstetricians Need to Know About Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in neonates, infants, and children worldwide. The virus is estimated to infect 97% of this population in the United States by the age of 2 years, leading to hospitalization for severe lower respiratory tract disease in 2-3% of infants younger than age 6 months. Two preventive options, prenatal administration of a maternal vaccine and administration of a long-acting monoclonal antibody to the infant, are now available for the prevention of RSV-associated lower respiratory tract infection in infants in the United States. The U.S. Food and Drug Administration (FDA) has approved and the Centers for Disease Control and Prevention (CDC) has recommended a new maternal vaccination, RSVPreF, to be administered between 32 0/7 and 36 6/7 weeks of gestation to reduce the risk of RSV-associated lower respiratory tract infection in infants in the first 6 months of life. The monoclonal antibody nirsevimab was approved by the FDA and recommended by the CDC for prevention of RSV-associated lower respiratory tract infection in infants younger than age 8 months who are born during or entering their first RSV season and for infants and children aged 8-19 months who are at high risk for RSV-associated lower respiratory tract infection and entering their second RSV season. Either maternal vaccination during pregnancy or monoclonal antibody administration to the infant is recommended to prevent RSV-associated lower respiratory tract infection among infants, but both are not needed for most infants. Given that the availability of these products may vary as these recommendations are implemented, it is important that obstetricians and other prenatal practitioners have the information they need to counsel their pregnant patients about both options. We review the safety and efficacy of these products, current recommendations for their use, and relative advantages and disadvantages of both newly approved options for the prevention of RSV-associated lower respiratory tract infection in infants to assist obstetricians and other prenatal practitioners in their counseling of pregnant patients.

Resveratrol inhibits respiratory syncytial virus replication by targeting heparan sulfate proteoglycans

Resveratrol, renowned as an antioxidant, also exhibits significant potential in combatting severe respiratory infections, particularly the respiratory syncytial virus (RSV). Nevertheless, the specific mechanism underlying its inhibition of RSV replication remains unexplored. Heparan sulfate proteoglycans (HSPGs) play a pivotal role as attachment factors for numerous viruses, offering a promising avenue for countering viral infections. Our research has unveiled that resveratrol effectively curbs RSV infection in a dose-dependent manner. Remarkably, resveratrol disrupts the early stages of RSV infection by engaging with HSPGs, rather than interacting with RSV surface proteins like fusion (F) protein and glycoprotein (G). Resveratrol's affinity appears to be predominantly directed towards the negatively charged sites on HSPGs, thus impeding the binding of viral receptors. In an in vivo study involving RSV-infected mice, resveratrol demonstrates its potential by ameliorating pulmonary pathology. This improvement is attributed to the inhibition of pro-inflammatory cytokine expression and a reduction in viral load within the lungs. Notably, resveratrol specifically alleviates inflammation characterized by an abundance of neutrophils in RSV-infected mice. In summation, our data first shows how resveratrol combats RSV infection through interactions with HSPGs, positioning it as a promising candidate for innovative drug development targeting RSV infections. Our study provides insight into the mechanism of resveratrol antiviral infection.

Correlating Stability-Indicating Biochemical and Biophysical Characteristics with In Vitro Cell Potency in mRNA LNP Vaccine

The development of mRNA vaccines has increased rapidly since the COVID-19 pandemic. As one of the critical attributes, understanding mRNA lipid nanoparticle (LNP) stability is critical in the vaccine product development. However, the correlation between LNPs' physiochemical characteristics and their potency still remains unclear. The lack of regulatory guidance on the specifications for mRNA LNPs is also partially due to this underexplored relationship. In this study, we performed a three-month stability study of heat-stressed mRNA LNP samples. The mRNA LNP samples were analyzed for their mRNA degradation, LNP particle sizes, and mRNA encapsulation efficiency. In vitro cell potency was also evaluated and correlated with these above-mentioned physiochemical characterizations. The mRNA degradation-cell potency correlation data showed two distinct regions, indicating a critical cut-off size limit for mRNA degradation. The same temperature dependence was also observed in the LNP size-cell potency correlation.

Safety, Immunogenicity, and Mechanism of a Rotavirus mRNA-LNP Vaccine in Mice

Rotaviruses (RVs) are a major cause of diarrhea in young children worldwide. The currently available and licensed vaccines contain live attenuated RVs. Optimization of live attenuated RV vaccines or developing non-replicating RV (e.g., mRNA) vaccines is crucial for reducing the morbidity and mortality from RV infections. Herein, a nucleoside-modified mRNA vaccine encapsulated in lipid nanoparticles (LNP) and encoding the VP7 protein from the G1 type of RV was developed. The 5' untranslated region of an isolated human RV was utilized for the mRNA vaccine. After undergoing quality inspection, the VP7-mRNA vaccine was injected by subcutaneous or intramuscular routes into mice. Mice received three injections in 21 d intervals. IgG antibodies, neutralizing antibodies, cellular immunity, and gene expression from peripheral blood mononuclear cells were evaluated. Significant differences in levels of IgG antibodies were not observed in groups with adjuvant but were observed in groups without adjuvant. The vaccine without adjuvant induced the highest antibody titers after intramuscular injection. The vaccine elicited a potent antiviral immune response characterized by antiviral clusters of differentiation CD8+ T cells. VP7-mRNA induced interferon-γ secretion to mediate cellular immune responses. Chemokine-mediated signaling pathways and immune response were activated by VP7-mRNA vaccine injection. The mRNA LNP vaccine will require testing for protective efficacy, and it is an option for preventing rotavirus infection.

All Eyes on the Prefusion-Stabilized F Construct, but Are We Missing the Potential of Alternative Targets for Respiratory Syncytial Virus Vaccine Design?

Respiratory Syncytial Virus (RSV) poses a significant global health concern as a major cause of lower respiratory tract infections (LRTIs). Over the last few years, substantial efforts have been directed towards developing vaccines and therapeutics to combat RSV, leading to a diverse landscape of vaccine candidates. Notably, two vaccines targeting the elderly and the first maternal vaccine have recently been approved. The majority of the vaccines and vaccine candidates rely solely on a prefusion-stabilized conformation known for its highly neutralizing epitopes. Although, so far, this antigen design appears to be successful for the elderly, our current understanding remains incomplete, requiring further improvement and refinement in this field. Pediatric vaccines still have a long journey ahead, and we must ensure that vaccines currently entering the market do not lose efficacy due to the emergence of mutations in RSV's circulating strains. This review will provide an overview of the current status of vaccine designs and what to focus on in the future. Further research into antigen design is essential, including the exploration of the potential of alternative RSV proteins to address these challenges and pave the way for the development of novel and effective vaccines, especially in the pediatric population.

Expert consensus on the diagnosis, treatment, and prevention of respiratory syncytial virus infections in children

BACKGROUND

Respiratory syncytial virus (RSV) is the leading global cause of respiratory infections and is responsible for about 3 million hospitalizations and more than 100,000 deaths annually in children younger than 5 years, representing a major global healthcare burden. There is a great unmet need for new agents and universal strategies to prevent RSV infections in early life. A multidisciplinary consensus development group comprising experts in epidemiology, infectious diseases, respiratory medicine, and methodology aims to develop the current consensus to address clinical issues of RSV infections in children.

DATA SOURCES

The evidence searches and reviews were conducted using electronic databases, including PubMed, Embase, Web of Science, and the Cochrane Library, using variations in terms for "respiratory syncytial virus", "RSV", "lower respiratory tract infection", "bronchiolitis", "acute", "viral pneumonia", "neonatal", "infant" "children", and "pediatric".

RESULTS

Evidence-based recommendations regarding diagnosis, treatment, and prevention were proposed with a high degree of consensus. Although supportive care remains the cornerstone for the management of RSV infections, new monoclonal antibodies, vaccines, drug therapies, and viral surveillance techniques are being rolled out.

CONCLUSIONS

This consensus, based on international and national scientific evidence, reinforces the current recommendations and integrates the recent advances for optimal care and prevention of RSV infections. Further improvements in the management of RSV infections will require generating the highest quality of evidence through rigorously designed studies that possess little bias and sufficient capacity to identify clinically meaningful end points.

Arexvy: A Comprehensive Review of the Respiratory Syncytial Virus Vaccine for Revolutionary Protection

The respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infection in children and poses a significant risk to older adults. Developing a vaccine against RSV has been a priority, and the recently approved Arexvy vaccine has shown promise in preventing lower respiratory tract disease (LRTD) caused by RSV in individuals aged 60 years and older. This comprehensive review discusses the history of RSV, challenges in vaccine development, and the mechanism of action of Arexvy. The efficacy and safety of the vaccine are explored based on phase 3 clinical trial, demonstrating its effectiveness in preventing RSV-associated LRTD. The most common adverse reactions reported include injection site pain, fatigue, myalgia, headache, and arthralgia. Ongoing research focuses on the long-term effectiveness of Arexvy, including the need for booster doses and its impact on reducing RSV-associated hospitalizations. The potential of Arexvy to lessen the burden of RSV-related illnesses, particularly in vulnerable populations, is highlighted, emphasizing the importance of widespread immunization efforts and accessibility to this groundbreaking vaccine.

Induction of long-term tolerance to a specific antigen using anti-CD3 lipid nanoparticles following gene therapy

Development of factor VIII (FVIII) inhibitors is a serious complication in the treatment of hemophilia A (HemA) patients. In clinical trials, anti-CD3 antibody therapy effectively modulates the immune response of allograft rejection or autoimmune diseases without eliciting major adverse effects. In this study, we delivered mRNA-encapsulated lipid nanoparticles (LNPs) encoding therapeutic anti-CD3 antibody (αCD3 LNPs) to overcome the anti-FVIII immune responses in HemA mice. It was found that αCD3 LNPs encoding the single-chain antibodies (Fc-scFv) can efficiently deplete CD3+ and CD4+ effector T cells, whereas αCD3 LNPs encoding double-chain antibodies cannot. Concomitantly, mice treated with αCD3 (Fc-scFv) LNPs showed an increase in the CD4+CD25+Foxp3+ regulatory T cell percentages, which modulated the anti-FVIII immune responses. All T cells returned to normal levels within 2 months. HemA mice treated with αCD3 LNPs prior to hydrodynamic injection of liver-specific FVIII plasmids achieved persistent FVIII gene expression without formation of FVIII inhibitors. Furthermore, transgene expression was increased and persistent following secondary plasmid challenge, indicating induction of long-term tolerance to FVIII. Moreover, the treated mice maintained their immune competence against other antigens. In conclusion, our study established a potential new strategy to induce long-term antigen-specific tolerance using an αCD3 LNP formulation.

A lung-selective delivery of mRNA encoding broadly neutralizing antibody against SARS-CoV-2 infection

The respiratory system, especially the lung, is the key site of pathological injury induced by SARS-CoV-2 infection. Given the low feasibility of targeted delivery of antibodies into the lungs by intravenous administration and the short half-life period of antibodies in the lungs by intranasal or aerosolized immunization, mRNA encoding broadly neutralizing antibodies with lung-targeting capability can perfectly provide high-titer antibodies in lungs to prevent the SARS-CoV-2 infection. Here, we firstly identify a human monoclonal antibody, 8-9D, with broad neutralizing potency against SARS-CoV-2 variants. The neutralization mechanism of this antibody is explained by the structural characteristics of 8-9D Fabs in complex with the Omicron BA.5 spike. In addition, we evaluate the efficacy of 8-9D using a safe and robust mRNA delivery platform and compare the performance of 8-9D when its mRNA is and is not selectively delivered to the lungs. The lung-selective delivery of the 8-9D mRNA enables the expression of neutralizing antibodies in the lungs which blocks the invasion of the virus, thus effectively protecting female K18-hACE2 transgenic mice from challenge with the Beta or Omicron BA.1 variant. Our work underscores the potential application of lung-selective mRNA antibodies in the prevention and treatment of infections caused by circulating SARS-CoV-2 variants.

Kaempferol: A Review of Current Evidence of Its Antiviral Potential

Kaempferol and its derivatives are flavonoids found in various plants, and a considerable number of these have been used in various medical applications worldwide. Kaempferol and its compounds have well-known antioxidant, anti-inflammatory and antimicrobial properties among other health benefits. However, the antiviral properties of kaempferol are notable, and there is a significant number of experimental studies on this topic. Kaempferol compounds were effective against DNA viruses such as hepatitis B virus, viruses of the alphaherpesvirinae family, African swine fever virus, and pseudorabies virus; they were also effective against RNA viruses, namely feline SARS coronavirus, dengue fever virus, Japanese encephalitis virus, influenza virus, enterovirus 71, poliovirus, respiratory syncytial virus, human immunodeficiency virus, calicivirus, and chikungunya virus. On the other hand, no effectiveness against murine norovirus and hepatitis A virus could be determined. The antiviral action mechanisms of kaempferol compounds are various, such as the inhibition of viral polymerases and of viral attachment and entry into host cells. Future research should be focused on further elucidating the antiviral properties of kaempferol compounds from different plants and assessing their potential use to complement the action of antiviral drugs.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

A Rift Valley fever mRNA vaccine elicits strong immune responses in mice and rhesus macaques

Rift Valley fever virus (RVFV) is listed as a priority pathogen by the World Health Organization (WHO) because it causes serious and fatal disease in humans, and there are currently no effective countermeasures. Therefore, it is urgent to develop a safe and efficacious vaccine. Here, we developed six nucleotide-modified mRNA vaccines encoding different regions of the Gn and Gc proteins of RVFV encapsulated in lipid nanoparticles, compared their ability to induce immune responses in mice and found that mRNA vaccine encoding the full-length Gn and Gc proteins had the strongest ability to induce cellular and humoral immune responses. IFNAR(-/-) mice vaccinated with mRNA-GnGc were protected from lethal RVFV challenge. In addition, mRNA-GnGc induced high levels of neutralizing antibodies and cellular responses in rhesus macaques, as well as antigen-specific memory B cells. These data demonstrated that mRNA-GnGc is a potent and promising vaccine candidate for RVFV.

Respiratory Syncytial Virus Vaccines: A Review of the Candidates and the Approved Vaccines

Respiratory syncytial virus (RSV) is responsible for a significant proportion of global morbidity and mortality affecting young children and older adults. In the aftermath of formalin-inactivated RSV vaccine development, the effort to develop an immunizing agent was carefully guided by epidemiologic and pathophysiological evidence of the virus, including various vaccine technologies. The pipeline of RSV vaccine development includes messenger ribonucleic acid (mRNA), live-attenuated (LAV), subunit, and recombinant vector-based vaccine candidates targeting different virus proteins. The availability of vaccine candidates of various technologies enables adjustment to the individualized needs of each vulnerable age group. Arexvy® (GSK), followed by Abrysvo® (Pfizer), is the first vaccine available for market use as an immunizing agent to prevent lower respiratory tract disease in older adults. Abrysvo is additionally indicated for the passive immunization of infants by maternal administration during pregnancy. This review presents the RSV vaccine pipeline, analyzing the results of clinical trials. The key features of each vaccine technology are also mentioned. Currently, 24 vaccines are in the clinical stage of development, including the 2 licensed vaccines. Research in the field of RSV vaccination, including the pharmacovigilance methods of already approved vaccines, promotes the achievement of successful prevention.

Mitigating the effects of climate change on human health with vaccines and vaccinations

Climate change represents an unprecedented threat to humanity and will be the ultimate challenge of the 21st century. As a public health consequence, the World Health Organization estimates an additional 250,000 deaths annually by 2030, with resource-poor countries being predominantly affected. Although climate change's direct and indirect consequences on human health are manifold and far from fully explored, a growing body of evidence demonstrates its potential to exacerbate the frequency and spread of transmissible infectious diseases. Effective, high-impact mitigation measures are critical in combating this global crisis. While vaccines and vaccination are among the most cost-effective public health interventions, they have yet to be established as a major strategy in climate change-related health effect mitigation. In this narrative review, we synthesize the available evidence on the effect of climate change on vaccine-preventable diseases. This review examines the direct effect of climate change on water-related diseases such as cholera and other enteropathogens, helminthic infections and leptospirosis. It also explores the effects of rising temperatures on vector-borne diseases like dengue, chikungunya, and malaria, as well as the impact of temperature and humidity on airborne diseases like influenza and respiratory syncytial virus infection. Recent advances in global vaccine development facilitate the use of vaccines and vaccination as a mitigation strategy in the agenda against climate change consequences. A focused evaluation of vaccine research and development, funding, and distribution related to climate change is required.

Oxidative stress and ROS-mediated cellular events in RSV infection: potential protective roles of antioxidants

Respiratory syncytial virus (RSV), a member of the Pneumoviridae family, can cause severe acute lower respiratory tract infection in infants, young children, immunocompromised individuals and elderly people. RSV is associated with an augmented innate immune response, enhanced secretion of inflammatory cytokines, and necrosis of infected cells. Oxidative stress, which is mainly characterized as an imbalance in the production of reactive oxygen species (ROS) and antioxidant responses, interacts with all the pathophysiologic processes above and is receiving increasing attention in RSV infection. A gradual accumulation of evidence indicates that ROS overproduction plays an important role in the pathogenesis of severe RSV infection and serves as a major factor in pulmonary inflammation and tissue damage. Thus, antioxidants seem to be an effective treatment for severe RSV infection. This article mainly reviews the information on oxidative stress and ROS-mediated cellular events during RSV infection for the first time.

mRNA vaccines against respiratory viruses

PURPOSE OF REVIEW

The successes of the coronavirus disease 2019 (COVID-19) mRNA vaccines have accelerated the development of mRNA vaccines against other respiratory pathogens. The aim of this review is to highlight COVID-19 mRNA vaccine advances and provide an update on the progress of mRNA vaccine development against other respiratory pathogens.

RECENT FINDINGS

The COVID-19 mRNA vaccines demonstrated effectiveness in preventing severe COVID-19 and death. H7N9 and H10N8 avian influenza mRNA vaccines have demonstrated safety and immunogenicity in phase 1 clinical trials. Numerous seasonal influenza mRNA vaccines are in phase 1-3 clinical trials. Respiratory syncytial virus (RSV) mRNA vaccines have progressed to phase 2-3 clinical trials in adults and a phase 1 clinical trial in children. A combined human metapneumovirus and parainfluenza-3 mRNA vaccines was found to be well tolerated and immunogenic in a phase 1 trial among adults and trials are being conducted among children. Clinical trials of mRNA vaccines combining antigens from multiple respiratory viruses are underway.

SUMMARY

The development of mRNA vaccines against respiratory viruses has progressed rapidly in recent years. Promising vaccine candidates are moving through the clinical development pathway to test their efficacy in preventing disease against respiratory viral pathogens.

Vaccines' New Era-RNA Vaccine

RNA vaccines, including conventional messenger RNA (mRNA) vaccines, circular RNA (circRNA) vaccines, and self-amplifying RNA (saRNA) vaccines, have ushered in a promising future and revolutionized vaccine development. The success of mRNA vaccines in combating the COVID-19 pandemic caused by the SARS-CoV-2 virus that emerged in 2019 has highlighted the potential of RNA vaccines. These vaccines possess several advantages, such as high efficacy, adaptability, simplicity in antigen design, and the ability to induce both humoral and cellular immunity. They also offer rapid and cost-effective manufacturing, flexibility to target emerging or mutant pathogens and a potential approach for clearing immunotolerant microbes by targeting bacterial or parasitic survival mechanisms. The self-adjuvant effect of mRNA-lipid nanoparticle (LNP) formulations or circular RNA further enhances the potential of RNA vaccines. However, some challenges need to be addressed. These include the technology's immaturity, high research expenses, limited duration of antibody response, mRNA instability, low efficiency of circRNA cyclization, and the production of double-stranded RNA as a side product. These factors hinder the widespread adoption and utilization of RNA vaccines, particularly in developing countries. This review provides a comprehensive overview of mRNA, circRNA, and saRNA vaccines for infectious diseases while also discussing their development, current applications, and challenges.

Risk Factors for Severe Respiratory Syncytial Virus Infection in Hospitalized Children

BACKGROUND

RSV often leads to hospitalization, and accurate knowledge of risk factors is crucial.

METHODS

We retrospectively analyzed laboratory-confirmed RSV hospitalizations regarding pregnancy factors, birth status, cigarette smoke exposure, nutrition, social conditions, clinical presentation, and severe disease defined as a need for passive oxygen therapy (pO2Tx), the presence of pneumonia, respiratory failure, intensive care unit (ICU) transfer, and prolonged hospitalization.

RESULTS

A univariate analysis included 594 children (median age 4 months) and revealed a pO2Tx relationship with age ≤ 3 months (OR = 1.56), prematurity (OR = 1.71), being born during RSV season (OR = 1.72), smoke exposure during pregnancy (both parents (OR = 2.41, father (OR = 1.8)), dyspnea (OR = 5.09), and presence of apnea (OR = 5.81). Pneumonia was associated with maternal smoke exposure (OR = 5.01), fever (OR = 3.92), dyspnea (OR = 1.62), history of aspiration (OR = 4.63), and inversely with age ≤ 3 months (OR = 0.45). Respiratory failure was associated with prematurity (OR = 3.13) and apnea (OR = 18.78), while the lower odds were associated with older age (OR = 0.57 per month) and presence of fever (OR = 0.11). ICU transfer was associated with apnea (OR = 17.18), but an inverse association was observed with age (OR = 0.54) and fever (OR = 0.11). A prolonged hospital stay was associated with prematurity (OR = 1.76), low birth weight (OR = 2.89), aspiration (OR = 4.93), and presence of fever (OR = 1.51).

CONCLUSIONS

Age (up to 3 months), prematurity, and presence of apnea are risk factors for a severe RSV course.

The SeroNet Clinical and Translational Serology Task Force (CTTF) SARS-CoV-2 mucosal immunity methodological considerations and best practices workshop

SARS-CoV-2 persists in certain populations, even with vaccination and boosters. Emerging evidence suggests that reductions in virus transmission and infection will likely require involvement of the mucosal immune system, especially secretory antibodies in the upper respiratory tract. The Clinical and Translational Serology Task Force (CTTF) within The National Cancer Institute (NCI)'s Serological Sciences Network for COVID-19 (SeroNet) hosted a workshop to review the status of development and standardization of mucosal sample collection methods and assays, identify challenges, and develop action plans to bridge gaps. Speakers presented data underscoring a role for secretory IgA in protection, mucosal markers as correlates of protection, methods for tracking and assessing mucosal antibodies, and lessons learned from other infectious agents. Perspectives from regulators and industry were put forward to guide mucosal vaccine development. Methodological considerations for optimizing collection protocols and assays and harmonizing data were highlighted. Rigorous studies, standardized protocols, controls, standards, and assay validation were identified as necessary to gain momentum in expanding SARS-CoV-2 vaccines to the mucosa.

Dissolving Microneedles Loaded with Nanoparticle Formulation of Respiratory Syncytial Virus Fusion Protein Virus-like Particles (F-VLPs) Elicits Cellular and Humoral Immune Responses

Respiratory syncytial virus (RSV) is one of the leading causes of bronchiolitis and pneumonia in children ages five years and below. Recent outbreaks of the virus have proven that RSV remains a severe burden on healthcare services. Thus, a vaccine for RSV is a need of the hour. Research on novel vaccine delivery systems for infectious diseases such as RSV can pave the road to more vaccine candidates. Among many novel vaccine delivery systems, a combined system with polymeric nanoparticles loaded in dissolving microneedles holds a lot of potential. In this study, the virus-like particles of the RSV fusion protein (F-VLP) were encapsulated in poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs). These NPs were then loaded into dissolving microneedles (MNs) composed of hyaluronic acid and trehalose. To test the in vivo immunogenicity of the nanoparticle-loaded microneedles, Swiss Webster mice were immunized with the F-VLP NPs, both with and without adjuvant monophosphoryl lipid A (MPL) NPs loaded in the MN. The mice immunized with the F-VLP NP + MPL NP MN showed high immunoglobulin (IgG and IgG2a) levels both in the serum and lung homogenates. A subsequent analysis of lung homogenates post-RSV challenge revealed high IgA, indicating the generation of a mucosal immune response upon intradermal immunization. A flowcytometry analysis showed high CD8+ and CD4+ expression in the lymph nodes and spleens of the F-VLP NP + MPL NP MN-immunized mice. Thus, our vaccine elicited a robust humoral and cellular immune response in vivo. Therefore, PLGA nanoparticles loaded in dissolving microneedles could be a suitable novel delivery system for RSV vaccines.

mRNA vaccines: The future of prevention of viral infections?

Messenger RNA (mRNA) vaccines against COVID-19 are the first authorized biological preparations developed using this platform. During the pandemic, their administration has been proven to be a life-saving intervention. Here, we review the main advantages of using mRNA vaccines, identify further technological challenges to be met during the development of the mRNA platform, and provide an update on the clinical progress on leading mRNA vaccine candidates against different viruses that include influenza viruses, human immunodeficiency virus 1, respiratory syncytial virus, Nipah virus, Zika virus, human cytomegalovirus, and Epstein-Barr virus. The prospects and challenges of manufacturing mRNA vaccines in low-income countries are also discussed. The ongoing interest and research in mRNA technology are likely to overcome some existing challenges for this technology (e.g., related to storage conditions and immunogenicity of some components of lipid nanoparticles) and enhance the portfolio of vaccines against diseases for which classical formulations are already authorized. It may also open novel pathways of protection against infections and their consequences for which no safe and efficient immunization methods are currently available.

Vaccination against Community-Acquired Pneumonia in Spanish Adults: Practical Recommendations by the NeumoExperts Prevention Group

In the adult population, community-acquired pneumonia (CAP) is a serious disease that is responsible for high morbidity and mortality rates, being frequently associated with multidrug resistant pathogens. The aim of this review is to update a practical immunization prevention guideline for CAP in Spain caused by prevalent respiratory pathogens, based on the available scientific evidence through extensive bibliographic review and expert opinion. The emergence of COVID-19 as an additional etiological cause of CAP, together with the rapid changes in the availability of vaccines and recommendations against SARS-CoV-2, justifies the need for an update. In addition, new conjugate vaccines of broader spectrum against pneumococcus, existing vaccines targeting influenza and pertussis or upcoming vaccines against respiratory syncytial virus (RSV) will be very useful prophylactic tools to diminish the burden of CAP and all of its derived complications. In this manuscript, we provide practical recommendations for adult vaccination against the pathogens mentioned above, including their contribution against antibiotic resistance. This guide is intended for the individual perspective of protection and not for vaccination policies, as we do not pretend to interfere with the official recommendations of any country. The use of vaccines is a realistic approach to fight these infections and ameliorate the impact of antimicrobial resistance. All of the recently available scientific evidence included in this review gives support to the indications established in this practical guide to reinforce the dissemination and implementation of these recommendations in routine clinical practice.