Search Results (2,719)

Streptococcus pyogenes (Group A Streptococcus, StrepA) is a human pathogen responsible for hundreds of millions of infections each year and remains one of the most prevalent bacterial causes of upper respiratory and skin infections worldwide. Despite its global impact, there is no approved vaccine, and the optimal protective immune response is still not fully understood. In particular, the role of Th17 T cells in immunity against StrepA remains to be explored. We have previously shown that Th17 T cells are induced in humans following StrepA infection. In this study, we investigated the role of Th17 T cells during skin and upper airway StrepA infections. To generate StrepA-specific Th17 T cells, we utilized a novel cationic liposomal adjuvant system. We demonstrated that vaccine-induced Th17 T cells are recruited to the skin and upper airways upon StrepA infection. In the airways, Th17 T cells and IgA correlate with protection, whereas Th1 T cells and IgG do not. To further characterize the recruited Th17 T cells, we used an IL-17 fate-reporter mouse model to track Th17 T cells. Our results show that Th17 T cells outnumber bona fide Th1 T cells in both StrepA-infected skin and upper airways. Surprisingly, most Th17 T cells lose expression of IL-17, and do not express TNFα, IFNγ, and IL-2. Initial single-cell sequencing data suggest the existence of multiple Th17 T cell subsets with distinct expression profiles. We discuss the functional relevance of these subsets in the context of a StrepA infection. Full article

Despite the widespread accessibility of vaccines and antivirals, seasonal influenza virus epidemics continue to pose a threat to public health. In this study, we constructed a recombinant replication-deficient simian adenovirus type 25 vector carrying the full-length hemagglutinin (HA) of the H1N1 influenza virus, named rSAd25-H1. Both systemic and mucosal humoral immune responses, as well as the protective efficacy, were assessed in mice immunized via the intramuscular (IM) or intranasal (IN) route. A single-dose IM or IN administration of rSAd25-H1 elicited a robust systemic IgG antibody response, including hemagglutination inhibition antibodies. As expected, only IN immunization was able to induce IgA production in serum and respiratory mucosa. Notably, a single dose of rSAd25-H1 at the highest dose (10¹⁰ viral particles) conferred complete protection against lethal homologous H1N1 challenge in mice despite the route of administration. These findings demonstrate the potential of simian adenovirus type 25-based vectors as a promising candidate for intranasal vaccine development targeting respiratory pathogens. Full article

Porcine reproductive and respiratory syndrome virus (PRRSV), an enveloped single-stranded positive-sense RNA virus, poses a significant threat to global swine production. Despite the availability of modified live virus and inactivated vaccines, their limited efficacy and safety concerns highlight the urgent need for novel antiviral therapeutics. This study aimed to investigate the molecular mechanisms by which lycopene inhibits PRRSV replication. Initial assessments confirmed that lycopene did not adversely affect cellular viability, cell cycle progression, or apoptosis. Using fluorescence microscopy, flow cytometry, immunoblotting, quantitative real-time PCR (qRT-PCR), and viral titration assays, lycopene was shown to exhibit potent antiviral activity against PRRSV. Mechanistic studies revealed that lycopene suppresses reactive oxygen species (ROS) production, which is critical for PRRSV proliferation. Additionally, lycopene attenuated PRRSV-induced inflammatory responses, as demonstrated by immunoblotting, ELISA, and qRT-PCR assays. These findings suggest that lycopene inhibits PRRSV replication by modulating ROS levels and mitigating inflammation, offering a promising avenue for the development of antiviral therapeutics. This study provides new insights and strategies for combating PRRSV infections, emphasizing the potential of lycopene as a safe and effective antiviral agent. Full article

Background/Objective: The COVID-19 pandemic profoundly transformed social life worldwide, indiscriminately affecting individuals across all age groups. Children have not been exempted from the risk of severe illness and death caused by COVID-19. Objective: This paper sought to describe the clinical findings, laboratory and imaging results, and hospital care provided for severe and critical cases of COVID-19 in unvaccinated children, with or without severe asthma, hospitalized in a public referral service for COVID-19 treatment in the Brazilian state of Pernambuco. Methods: This was a case series study of severe and critical COVID-19 in hospitalized, unvaccinated children, with or without severe asthma, conducted in a public referral hospital between March 2020 and June 2021. Results: The case series included 80 children, aged from 1 month to 11 years, with the highest frequency among those under 2 years old (58.8%) and a predominance of males (65%). Respiratory diseases, including severe asthma, were present in 73.8% of the cases. Pediatric multisystem inflammatory syndrome occurred in 15% of the children, some of whom presented with cardiac involvement. Oxygen therapy was required in 65% of the cases, mechanical ventilation in 15%, and 33.7% of the children required intensive care in a pediatric intensive care unit. Pulmonary infiltrates and ground-glass opacities were common findings on chest X-rays and CT scans; inflammatory markers were elevated, and the most commonly used medications were antibiotics, bronchodilators, and corticosteroids. Conclusions: This case series has identified key characteristics of children with severe and critical COVID-19 during a period when vaccines were not yet available in Brazil for the study age group. However, the persistence of low vaccination coverage, largely due to parental vaccine hesitancy, continues to leave children vulnerable to potentially severe illness from COVID-19. These findings may inform the development of public health emergency contingency plans, as well as clinical protocols and care pathways, which can guide decision-making in pediatric care and ensure appropriate clinical management, ultimately improving the quality of care provided. Full article

Since late 2023, an increase in Bordetella pertussis infections has been noticed in Europe, particularly among children. Our data showed the upward trend of B. pertussis cases in the Lazio region, even among adults with severe influenza-like illnesses, highlighting the necessity for maintaining high vaccination rates across both children and adults. These findings underscore the urgent need for clinicians to maintain a high index of suspicion for B. pertussis in patients with respiratory symptoms, prioritize nasopharyngeal swabs for accurate diagnosis, assess for co-infections, verify booster vaccination status in adults, and support timely reporting to public health authorities. Full article

Background/objectives: This was a post hoc analysis of safety data across the bivalent respiratory syncytial virus prefusion F (RSVpreF) vaccine clinical trial development program. Methods: Data from eight clinical trials in 46,913 immunocompetent adults who received RSVpreF or placebo were analyzed. Local reactions and systemic events were assessed among non-pregnant ≥18-year-olds (n = 9517); adverse events (AEs) among pregnant and non-pregnant 18–59-year-olds (n = 9238); and vaccine-related AEs among non-pregnant ≥18-year-olds (n = 39,314). Post-marketing data in non-pregnant adults were considered. Results: Local reactions and systemic events were reported more frequently in RSVpreF versus placebo recipients; injection site pain was the most common local reaction (RSVpreF, 18.9%; placebo, 7.4%), and fatigue (23.5%; 18.4%) and headache (19.5%; 15.0%) were the most common systemic events. Percentages of AEs within 1 month after vaccination were similar across groups (RSVpreF, 12.8%; placebo, 13.1%); severe AEs were reported in ≤1.5% of participants. Differences in percentages of individuals reporting vaccine-related AEs between the RSVpreF and placebo groups were <0.2% for all related AEs. Serious AEs throughout the study were reported in ≤14.0% (RSVpreF, 12.6%; placebo, 14.0%). No atrial fibrillation, Guillain-Barré syndrome, or acute polyneuropathy cases were reported. The AE data from post-marketing data sources were consistent with the safety profile from the clinical trial program, with no new safety concerns. Conclusions: Integrated data demonstrated that RSVpreF was well tolerated with a favorable safety profile in non-pregnant and pregnant adults. Ongoing surveillance through real-world use and clinical trial experience continue to support the safety profile of RSVpreF. ClinicalTrials.gov: NCT03529773/NCT04071158/NCT04785612/NCT05035212/NCT05096208/NCT05842967/NCT04032093/NCT04424316. Full article

Background/Objectives: Viral respiratory infections have a significant impact on global health and the economy. While vaccines are effective in preventing infection, they might not be available or sufficient when used alone and must be complemented by specific therapeutic strategies. The development of new antiviral agents is increasingly important due to the continual emergence of novel respiratory pathogens. Previously we identified bovine lactoferrin (bLf)-derived tetrapeptides and peptidomimetics that showed potent in vitro activity against the influenza A virus in the picomolar range. Methods: Inspired by these results, in this study, we evaluated the antiviral potential of these compounds against HCoV-229E, a human coronavirus that can cause severe disease in immunocompromised individuals, using a compound repositioning approach. Results: Functional studies revealed that SK(N-Me)HS (3) interferes with viral entry and replication, while compound SNKHS (5) primarily blocks infection in the early stages. Biophysical analyses confirmed the occurrence of high-affinity binding to the viral spike protein, and computational studies suggested that the compounds target a region involved in conformational changes necessary for membrane fusion. Conclusions: These findings highlight these compounds as promising candidates for coronavirus entry inhibition and underscore the value of compound repurposing in antiviral development. Full article

Background/Objectives: Mucosal vaccines, delivered intranasally or via inhalation, are being studied for respiratory infectious diseases like COVID-19 and influenza. These vaccines aim to provide non-invasive administration and strong immune responses at infection sites, making them a promising area of research. This systematic review and meta-analysis assessed their immunogenicity, safety, and protective efficacy. Methods: The study design was a systematic review and meta-analysis, searching PubMed and Cochrane databases up to 30 May 2025. Inclusion criteria followed the PICOS framework, focusing on mucosal vaccines for COVID-19, influenza, RSV, pertussis, and tuberculosis. Results: A total of 65 studies with 229,614 participants were included in the final analysis. Mucosal COVID-19 vaccines elicited higher neutralizing antibodies compared to intramuscular vaccines (SMD = 2.48, 95% CI: 2.17–2.78 for wild-type; SMD = 1.95, 95% CI: 1.32–2.58 for Omicron), with varying efficacy by route (inhaled VE = 47%, 95% CI: 22–74%; intranasal vaccine VE = 17%, 95% CI: 0–31%). Mucosal influenza vaccines protected children well (VE = 62%, 95% CI: 30–46%, I² = 17.1%), but seroconversion rates were lower than those of intramuscular vaccines. RSV and pertussis vaccines had high seroconversion rates (73% and 52%, respectively). Tuberculosis vaccines were reviewed systemically, exhibiting robust cellular immunogenicity. Safety was comparable to intramuscular vaccines or placebo, with no publication bias detected. Conclusions: Current evidence suggests mucosal vaccines are immunogenic, safe, and protective, particularly for respiratory diseases. This review provides insights for future research and vaccination strategies, though limitations include varying efficacy by route and study heterogeneity. Full article

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infections (ALRIs) in young children, especially bronchiolitis, with significant global health and economic impact. Increasing evidence links early-life RSV infection to long-term respiratory complications, notably recurrent wheezing and asthma. This narrative review examines these associations, emphasizing predictive factors and emerging biomarkers for risk stratification. Early RSV infection can trigger persistent airway inflammation and immune dysregulation, increasing the likelihood of chronic respiratory outcomes. Risk factors include severity of the initial infection, age at exposure, genetic susceptibility, prematurity, air pollution, and tobacco smoke. Biomarkers such as cytokines and chemokines are showing promise in identifying children at higher risk, potentially guiding early interventions. RSV-related bronchiolitis may also induce airway remodeling and promote Th2/Th17-skewed immune responses, mechanisms closely linked to asthma development. Advances in molecular profiling are shedding light on these pathways, suggesting novel targets for early therapeutic strategies. Furthermore, passive immunization and maternal vaccination offer promising approaches to reducing both acute and long-term RSV-related morbidity. A deeper understanding of RSV’s prolonged impact is essential to develop targeted prevention, enhance risk prediction, and improve long-term respiratory health in children. Future studies should aim to validate biomarkers and refine immunoprophylactic strategies. Full article

Background/Objectives: This retrospective multicenter study, conducted within the ORCHESTRA Project, investigated SARS-CoV-2 reinfections among 5777 healthcare workers (HCWs) from four University Hospitals (Modena, Verona, Padova and Trieste) in northern Italy, aiming to assess the risk of reinfection and its determinants, comparing the clinical characteristics of reinfections with those of first infections, and examining the impact of preventive measures and vaccination strategies. Methods: HCWs completed an online questionnaire between June and August 2022. The survey collected demographic, occupational, and clinical data, including information on first infections and reinfections. Statistical analyses were performed using SPSS 28.0, through bivariate and multivariate approaches. Results: Response rates were 41.8% for Modena, 39.5% for Verona, 17.9% for Padova, and 17.4% for Trieste. Among the respondents, 4.8% (n = 276) experienced 2 infections and 0.5% (n = 27) reported 3 infections, out of a total of 330 reinfection cases. Additionally, 43.0% (n = 2787) reported only one infection, while 51.5% were never infected. Reinfection rates increased across five study phases (based on the epidemiological context), likely due to the emergence of new SARS-CoV-2 variants. A booster vaccine dose significantly reduced reinfection risk. Higher reinfection risk was found among HCWs aged ≤30 years, those with chronic respiratory diseases, and those working in COVID-19 wards, particularly nurses and allied health professionals. Reinfections were associated with a lower frequency of symptoms both during the period of swab positivity and after a negative swab, as well as with a shorter duration of swab positivity. No significant differences in symptom duration were found between first infections and reinfections. Conclusions: Despite its limitations, the online questionnaire proved a useful tool. Natural infection and vaccination reduced both reinfection risk and symptom severity. Prior infections should be considered in planning vaccination schedules and prioritizing HCWs. Full article

Background: Since the COVID-19 pandemic, managing acute infections in symptomatic individuals, regardless of vaccination status, has been widely debated and extensively studied. Even more concerning, however, is the impact of COVID-19 on pregnant women—especially its effects on fetuses and newborns. Several studies have documented complications in both expectant mothers and their infants following infection. Methods: In our previous works, we provided scientific evidence of the bacteriophage behavior of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2). This demonstrated that a well-defined combination of two antibiotics, amoxicillin and rifaximin, is associated with the same statistics for subjects affected by severe cases of SARS-CoV-2, regardless of vaccination status. We considered the few cases in the literature regarding the management of pregnancies infected with SARS-CoV-2, as well as previous data published in our works. In this brief case series, we present two pregnancies from the same unvaccinated mother—one prior to the COVID-19 pandemic and the other during the spread of the Omicron variant—as well as one pregnancy from a mother vaccinated against COVID-19. We describe the management of acute maternal infection using a previously published protocol that addresses the bacteriophage and toxicological mechanisms associated with SARS-CoV-2. Results: The three pregnancies are compared based on fetal growth and ultrasound findings. This report highlights that, even in unvaccinated mothers, timely and well-guided management of symptomatic COVID-19 can result in positive outcomes. In all cases, intrauterine growth remained within excellent percentiles, and the births resulted in optimal APGAR scores. Conclusions: This demonstrates that a careful and strategic approach, guided by ultrasound controls, can support healthy pregnancies during SARS-CoV-2 infection, regardless of vaccination status. Full article

Artificial intelligence (AI) techniques—ranging from hybrid mechanistic–machine learning (ML) ensembles to gradient-boosted decision trees, support-vector machines, and deep neural networks—are transforming the management of seasonal influenza, respiratory syncytial virus (RSV), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Symptom-based triage models using eXtreme Gradient Boosting (XGBoost) and Random Forests, as well as imaging classifiers built on convolutional neural networks (CNNs), have improved diagnostic accuracy across respiratory infections. Transformer-based architectures and social media surveillance pipelines have enabled real-time monitoring of COVID-19. In HIV research, support-vector machines (SVMs), logistic regression, and deep neural network (DNN) frameworks advance viral-protein classification and drug-resistance mapping, accelerating antiviral and vaccine discovery. Despite these successes, persistent challenges remain—data heterogeneity, limited model interpretability, hallucinations in large language models (LLMs), and infrastructure gaps in low-resource settings. We recommend standardized open-access data pipelines and integration of explainable-AI methodologies to ensure safe, equitable deployment of AI-driven interventions in future viral-outbreak responses. Full article

Avian influenza viruses (AIVs) pose significant risks to occupational populations engaged in poultry farming, livestock handling, and live poultry market operations due to frequent exposure to infected animals and contaminated environments. This review synthesizes evidence on AIV exposure patterns and risk factors through a comprehensive analysis of viral characteristics, host dynamics, environmental influences, and human behaviors. The main routes of transmission include direct animal contact, respiratory contact during slaughter/milking, and environmental contamination (aerosols, raw milk, shared equipment). Risks increase as the virus adapts between species, survives longer in cold/wet conditions, and spreads through wild bird migration (long-distance transmission) and live bird trade (local transmission). Recommended control measures include integrated animal–human–environment surveillance, stringent biosecurity measures, vaccination, and education. These findings underscore the urgent need for global ‘One Health’ collaboration to assess risk and implement preventive measures against potentially pandemic strains of influenza A viruses, especially in light of undetected mild/asymptomatic cases and incomplete knowledge of viral evolution. Full article

Introduction: Respiratory Syncytial Virus (RSV) is the leading cause of lower respiratory tract infections in infants and children, as well as hospitalizations for respiratory infections in the pediatric population, representing a significant public health concern. Nirsevimab, a long-acting anti-RSV monoclonal antibody, has recently been approved by the European Medicines Agency (EMA). The aim of this study is to assess the utility of certain parameters, such as the Number Needed to Immunize (NNI), in supporting decision-makers regarding the introduction of nirsevimab as a universal prophylactic measure. Methods: A literature review was conducted to identify the definition and application of the NNI in the context of infectious disease prevention. The following online databases were consulted: Scopus, MEDLINE, Google Scholar, Web of Science, and Cochrane Library. The search was restricted to English-language texts published between 1 January 2000 and 30 January 2025. Results: The NNI represents the number of individuals who need to be immunized to prevent clinical outcomes such as medical visits and hospitalizations caused by infectious diseases. Six studies were identified that utilized this parameter to outline the benefits of immunization and describe the advantages of using monoclonal antibodies for RSV disease. Finelli and colleagues report that to prevent one RSV-related hospitalization, 37–85 infants aged 0–5 months and 107–280 infants aged 6–11 months would need to be immunized with long-acting anti-RSV antibodies. A recent study by Mallah et al. on the efficacy of nirsevimab estimates that the NNI required to prevent one RSV-related hospitalization is 25 infants. Studies by Francisco and O’Leary report NNI values of 82 and 128 infants, respectively, to prevent one RSV-related hospitalization with nirsevimab. Mallah et al. describe NNI as a metric useful to quantify the immunization effort needed to prevent a single RSV hospitalization. A recent Italian study reports that 35 infants need to be immunized to prevent one hospitalization due to RSV-LRTI and 3 infants need to be immunized to prevent one primary care visit due to RSV-LRTI. The studies indicate that the NNI for anti-RSV monoclonal antibodies is lower than the corresponding Number Needed to Vaccinate (NNV) for vaccines already included in national immunization programs. The main limitations of using this parameter include the absence of a shared threshold for interpreting results and the lack of consideration for the indirect effects of immunization on the population. Conclusions: The NNI is an easily understandable tool that can be used to convey the value of an immunization intervention to a variety of stakeholders, thereby supporting public health decision-making processes when considered in association with the uptake of the preventative strategy. At the current status, the estimated NNI of monoclonal antibodies against RSV results favourable and confirms the use in the first year of life for the prevention of RSV disease. Full article

The COVID-19 pandemic significantly impacted the circulation, seasonality, and disease burden of viral respiratory infections. This study aimed to evaluate the impact of SARS-CoV-2 on the frequency of viral respiratory infections at a teaching hospital in Southern Italy by comparing data from before, during, and after the COVID-19 pandemic and by investigating how the emergence of SARS-CoV-2 affected the circulation and seasonality of other respiratory viruses. This retrospective and prospective study was performed on de-identified nasopharyngeal specimens classified as pre-COVID-19 (before 15 March 2020), during-COVID-19 (from 16 March 2020 to 5 May 2023), and post-COVID-19 (from 6 May 2023 to 31 December 2024). Overall, 790 out of 3930 (20%) patient samples tested positive for at least one respiratory virus. The mean age of patients was 60 ± 19 years, with significant positivity rates observed in the 65–98 age group (p ≤ 0.05) across all periods. In the pre-COVID-19 period, the most prevalent virus was influenza A (47.5%, 47/99), followed by the human rhinovirus (19.2%, 19/99). During the COVID-19 pandemic, SARS-CoV-2 was the most prevalent (64.9%, 290/447), before decreasing to 38% (92/244) after the pandemic, while influenza A’s positivity prevalence increased to 14.3% (35/244). Rhinovirus/enterovirus remained relatively stable throughout all periods. The pandemic notably altered viral co-infection dynamics, with its effects lasting into the post-COVID-19 period. Specifically, a marked decrease in influenza A circulation was observed, while respiratory syncytial virus (RSV) epidemiology remained stable and significant co-circulation of rhinovirus/enterovirus with SARS-CoV-2 persisted. Therefore, since COVID-19 and influenza affect the same high-risk groups, those individuals must be vaccinated against both viruses. Full article