Update on current views and advances on RSV infection (Review)

Recent advances in natural products and derivatives with antiviral activity against respiratory syncytial virus (RSV)

Respiratory syncytial virus (RSV) is a widespread viral infection that causes millions of high-risk illnesses annually. Medicinal herbs such as ginseng root, echinacea purpurea, and radix astragali have a positive effect on antiviral activity by preventing viral adhesion, syncytial development, inhibiting viral internalization, relieving respiratory inflammation, strengthening the immune system, and stimulating the release of interferons. The potential benefits of natural products in terms of lower costs, better patient outcomes, and fewer adverse effects are discussed. This review examines the current evidence on the prevention and control of RSV with natural ingredients and the challenges and opportunities in clinical practice.

Antiviral C-geranylated flavonoids from Artocarpus communis

Ten C-geranylated flavonoids, along with three known analogues, were isolated from the leaves of Artocarpus communis. The chemical structures of these compounds were unambiguously determined via comprehensive spectroscopic analysis, single-crystal X-ray diffraction experiments, and quantum chemical electronic circular dichroism calculations. Structurally, artocarones A-I (1-9) represent a group of unusual, highly modified C-geranylated flavonoids, in which the geranyl chain is cyclised with the ortho-hydroxy group of flavonoids to form various heterocyclic scaffolds. Notably, artocarones E and G-I (5 and 7-9) feature a 6H-benzo[c]chromene core that is hitherto undescribed in C-geranylated flavonoids. Artocarone J (10) is the first example of C-9-C-16 connected C-geranylated aurone. Meanwhile, the plausible biosynthetic pathways for these rare C-geranylated flavonoids were also proposed. Notably, compounds 1, 2, 4, 8, 11, and 12 exhibited promising in vitro inhibitory activities against respiratory syncytial virus and herpes simplex virus type 1.

RNA-RNA interactions between respiratory syncytial virus and miR-26 and miR-27 are associated with regulation of cell cycle and antiviral immunity

microRNAs (miRNAs) regulate nearly all physiological processes but our understanding of exactly how they function remains incomplete, particularly in the context of viral infections. Here, we adapt a biochemical method (CLEAR-CLIP) and analysis pipeline to identify targets of miRNAs in lung cells infected with Respiratory syncytial virus (RSV). We show that RSV binds directly to miR-26 and miR-27 through seed pairing and demonstrate that these miRNAs target distinct gene networks associated with cell cycle and metabolism (miR-27) and antiviral immunity (miR-26). Many of the targets are de-repressed upon infection and we show that the miR-27 targets most sensitive to miRNA inhibition are those associated with cell cycle. Finally, we demonstrate that high confidence chimeras map to long noncoding RNAs (lncRNAs) and pseudogenes in transcriptional regulatory regions. We validate that a proportion of miR-27 and Argonaute 2 (AGO2) is nuclear and identify a long non-coding RNA (lncRNA) as a miR-27 target that is linked to transcriptional regulation of nearby genes. This work expands the target networks of miR-26 and miR-27 to include direct interactions with RSV and lncRNAs and implicate these miRNAs in regulation of key genes that impact the viral life cycle associated with cell cycle, metabolism, and antiviral immunity.

Evaluation of the Clinical, Laboratory and Radiology Findings and Treatment Methods of Children with Acute Bronchiolitis: Experience of a Tertiary Center

Objectives

The aim of this study is to determine the factors affecting the duration of hospitalization and causing the initiation of antibiotics in children with acute bronchiolitis.

Methods

This study was conducted retrospectively in Konya Training and Research Hospital. Demographic data, clinical features, laboratory and radiological findings, treatment methods and duration of hospitalization of 102 patients followed up in the pediatric service between September 2017 and April 2019 (in autumn, winter and spring seasons) were recorded from patient files.

Results

67 (65.7%) of 102 patients were male, and 35 (34.3%) were female. Median age was 6.5 (11.0) months. According to Wang bronchiolitis clinical scoring, 36 (35.3%) of the patients were mild, 51 (50.0%) were moderate, 15 (14.7%) were severe bronchiolitis The most common agents in polymerase chain reaction (PCR) were respiratory syncytial virus 60 (58.8%), influenza virus 20 (19.6%), rhinovirus 15 (14.7%), bocavirus 15 (14.7%) and parainfluenza virus 12 (11.7%). The median duration of hospitalization was 7.0 (4.0) days. Forty-two (41.2%) of the patients were hospitalized for ≤5 days, and 60 (58.8%) were hospitalized for >5 days. Duration of hospitalization was significantly and positively correlated with crepitant crackles, leukocytosis, neutrophilia, and coinfection with influenza virus (p=0.036, p=0.034, p=0.028, p=0.036, respectively). Duration of hospitalization was significantly and negatively correlated with pH and increased aeration (p=0.002, p=0.003, respectively) Antibiotic initiation was significantly and positively correlated with wheezing, crepitant crackles, leukocytosis, and neutrophilia (p=0.033, p=0.013, p=0.028, p=0.002, respectively).

Conclusion

A significant relationship was found between crepitant crackles in physical examination, respiratory acidosis in laboratory, co-infection with influenza virus detected by PCR and hospitalization for more than 5 days. A significant relationship was determined between wheezing or crepitant crackles in physical examination, leukocytosis or neutrophilia in laboratory and the initiation of antibiotic.

Respiratory syncytial virus-associated hospitalizations among children: an Italian retrospective observational study

BACKGROUND

Respiratory syncytial virus (RSV), a single-stranded RNA virus, is a leading cause of hospitalization in infants, especially ≤ 2 months of life. In the light new immunization strategies adoption, we described epidemiological and clinical characteristics of RSV-associated hospitalizations in pediatric and neonatal intensive care units of the Policlinico Foggia Hospital, Apulia Region, Italy.

METHODS

Hospitalized children with a laboratory-confirmed RSV infection from 2011 to 2023 were retrospectively evaluated. Clinical information was collected from Hospital Discharge Registry in the period 2011-2020. The proportion of the hospitalization for acute respiratory infections (ARIs) associated to RSV was calculated and the hospitalization cost was analyzed by using the diagnosis-related group reimbursement rate. The anticipated impact of immunization either with monoclonal antibodies or maternal immunization on the number of hospitalizations was estimated. All analyses and quality assessment were performed using STATA/SE15.0.

RESULTS

A total of 1,005 RSV-cases were included in the study, of which 86.3% occurred between December-March. In the period 2011-2020, 832 RSV-cases were matched with the corresponding hospital admissions; 75.2% were aged < 1 year (49.6% 0-2 months). Bronchiolitis was the most frequent admission diagnosis occurring in 63.3% of patients; 25% of children were affected by a very severe RSV-disease. Younger age ≤ 2 months (OR:14.8, 95%CI:8.30-26.31, p = 0.000), higher length-of-hospital-stay (OR:1.01, 95%CI:1.0-1.02, p = 0.030) and history of prematurity (OR:4.4, 95%CI:1.57-12.11, p = 0.005) were associated with a higher disease severity. RSV caused 48.9% of ARIs among children < 1 year. The mean cost of an RSV-associated hospitalization was 3,036 euros/year, with the higher cost in the 0-2 months age group (4,225 euros/year). Immunization programs with nirsevimab could prevent 51.4 RSV hospitalizations/year and 18.1 very severe RSV disease/year in infants < 1 year of age. RSV vaccine could prevent 46.1 of hospitalizations/year caused by RSV within 180 days after birth.

CONCLUSIONS

Our study contributes to outlining the baseline profile of RSV-associated hospitalizations among Italian children by providing epidemiological/clinical/economic estimates. While awaiting new recommendations on immunization, healthcare-workers should persist in implementing public health measures and appropriate case management to control RSV seasonal epidemics. Strengthened laboratory RSV surveillance is needed to inform the implementation of the new immunization strategies.

Immature granulocytes as an early clinical predictor in children with respiratory syncytial virus bronchiolitis

BACKGROUND

Immature granulocytes can be measured easily in a complete blood count by new automated hemolytic analyzers and have recently been studied as bio-markers in many infectious/inflammatory diseases. This study aims to investigate whether immature granulocyte percentage (IG%) would enable greater discrimination than conventionally utilized laboratory values in terms of early clinical prediction in instances with respiratory syncytial virus (RSV) bronchiolitis.

METHODS

A prospective observational cohort study involved 149 individuals with RSV bronchiolitis. Complete blood count (including IG%), C-reactive protein, and procalcitonin (PCT) assays were performed.

RESULTS

Sixty-two (42%) RSV bronchiolitis patients responded well to outpatient therapy; 60 (40%) were admitted to the hospital, and 27 (18%) required pediatric intensive care unit (PICU) follow up. Inpatients had a higher platelet count than outpatients, and PICU patients had a higher platelet lymphocyte ratio (PLR). Pediatric intensive care unit patients had greater PCT levels than outpatients, and their IG% was higher than that of both inpatient and outpatient groups. In the receiver operating characteristic analysis examining the usefulness of parameters in predicting PICU hospitalization, PLR, PCT, and IG% produced statistically significant findings, with IG% having the highest area under the curve (0.730).

CONCLUSIONS

Immature granulocyte percentage was the biomarker that best differentiated PICU patients from other patient groups when compared with traditional acute phase reactants. Immature granulocytes may help to determine the severity of infection/inflammation at an early stage of the disease.

Respiratory Syncytial Virus Infection: An Update

Respiratory syncytial virus (RSV) is a highly contagious respiratory virus that can cause mild to severe illness in children. It is the leading cause of lower respiratory tract infections (LRTI) in children under the age of one year, and it can also affect older children and adults, especially those with underlying medical conditions. In the post-COVID period, there seems to be an increase in the incidence, possibly due to 'immunity debt'. Symptoms of RSV infection in children may include fever, runny nose, and cough. In severe cases, it can lead to bronchiolitis (inflammation of the small airways in the lungs) or pneumonia (infection of the lungs). Most children with RSV infection recover within a week or two, but some may require hospitalization, especially those who are premature or have underlying medical conditions. As there is no specific treatment for RSV infection, supportive care is the mainstay of management. In severe cases, oxygen therapy or mechanical ventilation may be necessary. High flow nasal cannula seems to be beneficial. There have been promising advances in development of RSV vaccines; few trials in adults and pregnant women have reported encouraging results. The US FDA has approved two RSV vaccines for use in older adults (GSK's Arexvy and Pfizer's ABRYSVO).

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.

Natural killer cells and their exosomes in viral infections and related therapeutic approaches: where are we?

Innate immunity is the first line of the host immune system to fight against infections. Natural killer cells are the innate immunity lymphocytes responsible for fighting against virus-infected and cancerous cells. They have various mechanisms to suppress viral infections. On the other hand, viruses have evolved to utilize different ways to evade NK cell-mediated responses. Viruses can balance the response by regulating the cytokine release pattern and changing the proportion of activating and inhibitory receptors on the surface of NK cells. Exosomes are a subtype of extracellular vesicles that are involved in intercellular communication. Most cell populations can release these nano-sized vesicles, and it was shown that these vesicles produce identical outcomes to the originating cell from which they are released. In recent years, the role of NK cell-derived exosomes in various diseases including viral infections has been highlighted, drawing attention to utilizing the therapeutic potential of these nanoparticles. In this article, the role of NK cells in various viral infections and the mechanisms used by viruses to evade these important immune system cells are initially examined. Subsequently, the role of NK cell exosomes in controlling various viral infections is discussed. Finally, the current position of these cells in the treatment of viral infections and the therapeutic potential of their exosomes are reviewed. Video Abstract.

Common cold

The common cold is a unique human disease, as it is arguably the most common disease and because of the large number of respiratory viruses causing colds it is one of the most complex of human diseases. This review discusses the respiratory viruses and notes that all these viruses may cause the illness complex recognised as the common cold. The common cold is discussed as part of the "iceberg concept" of disease which ranges from asymptomatic infection to severe illness and death. The factors influencing the incidence of colds are discussed: crowding and sociability, stress, smoking and alcohol, immune status, sex, age, sleep, season, chilling, nutrition and exercise. The mechanism of symptoms related to the innate immune response is explained and symptomatic treatments are tabulated. Morbidity associated with common cold is discussed and possible vaccines.

The Importance of RSV Epidemiological Surveillance: A Multicenter Observational Study of RSV Infection during the COVID-19 Pandemic

The restrictive measures adopted worldwide against SARS-CoV-2 produced a drastic reduction in respiratory pathogens, including RSV, but a dramatic rebound was thereafter reported. In this multicenter retrospective observational study in 15 Pediatric Emergency Departments, all children <3 years old with RSV infection admitted between 1 September and 31 December 2021 were included and compared to those admitted in the same period of 2020 and 2019. The primary aim was to evaluate RSV epidemiology during and after the COVID-19 pandemic peak. The secondary aims were to evaluate the clinical features of children with RSV infection. Overall, 1015 children were enrolled: 100 in 2019, 3 in 2020 and 912 in 2021. In 2019, the peak was recorded in December, and in 2021, it was recorded in November. Comparing 2019 to 2021, in 2021 the median age was significantly higher and the age group 2-3 years was more affected. Admissions were significantly higher in 2021 than in 2020 and 2019, and the per-year hospitalization rate was lower in 2021 (84% vs. 93% in 2019), while the duration of admissions was similar. No difference was found in severity between 2019-2020-2021. In conclusion, after the COVID-19 pandemic, an increase in RSV cases in 2021 exceeding the median seasonal peak was detected, with the involvement of older children, while no difference was found in severity.

Molecular epidemiology of respiratory syncytial virus in children with acute respiratory illnesses in Africa: A systematic review and meta-analysis

Background

Globally, the respiratory syncytial virus (RSV) is the most common etiologic agent of acute respiratory illnesses in children. However, its burden has not been well addressed in developing countries. We aimed to estimate the molecular epidemiology of RSV in children less than 18 years of age with acute respiratory infections in Africa by conducting a systematic review and meta-analysis.

Methods

We systematically searched PubMed, Scopus, CINAHL, and Global Index Medicus databases to identify studies published from January 1, 2002, to April 27, 2022, following the PRISMA 2020 guideline. We assessed the study quality using the Joanna Brigg's Institute (JBI) critical appraisal checklists. We conducted a qualitative synthesis by describing the characteristics of included studies and performed the quantitative synthesis with random effects model using STATA-14. We checked for heterogeneity with Q statistics, quantified by I², and determined the prediction interval. We performed subgroup analyses to explain the sources of heterogeneity and assessed publication biases by funnel plots augmented with Egger's test.

Results

Eighty-eight studies with 105 139 participants were included in the review. The overall pooled prevalence of RSV in children <18 years of age was 23% (95% confidence interval (CI) = 20, 25%). Considerable heterogeneity was present across the included studies. The adjusted prediction interval was found to be 19%-27%. Heterogeneities were explained by subgroups analyses. The highest prevalence of RSV was found among inpatients, 28% (95% CI = 25, 31%) compared with inpatients/outpatients and outpatients, with statistically significant differences (P < 0.01). The RSV estimate was also highest among those with acute lower respiratory tract illnesses (ALRTIs), 28% (95% CI = 25, 31%) compared with acute upper respiratory tract illnesses (AURTIs) and both acute upper/lower respiratory manifestations, with statistically different prevalence (P < 0.01). RSV infection estimates in each sub-region of Africa were statistically different (P < 0.01). There were no statistically significant differences in RSV infections by designs, specimen types, and specimen conditions, despite them contributing to heterogeneity.

Conclusions

We found a high prevalence of RSV in pediatric populations with acute respiratory tract illnesses in Africa, highlighting that the prevention and control of RSV infections in children deserve more attention.

Registration

PROSPERO CRD42022327054.

Severe bronchiolitis profiling as the first step towards prevention of asthma

Bronchiolitis is the most common respiratory infection leading to hospitalization and constitutes a significant healthcare burden. The two main viral agents causing bronchiolitis, respiratory syncytial virus (RSV) and rhinovirus (RV), have distinct cytopathic, immune response, and clinical characteristics. Different approaches have been suggested for subtyping bronchiolitis based on viral etiology, atopic status, transcriptome profiles in blood, airway metabolome, lipidomic data, and airway microbiota. The highest risk of asthma at school age has been in a subgroup of bronchiolitis characterized by older age, high prevalence of RV infection, previous breathing problems, and/or eczema. Regarding solely viral etiology, RV-bronchiolitis in infancy has been linked to a nearly three times higher risk of developing asthma than RSV-bronchiolitis. Although treatment with betamimetics and systemic corticosteroids has been found ineffective in bronchiolitis overall, it can be beneficial for infants with severe RV bronchiolitis. Thus, there is a need to develop a more individualized therapeutic approach for bronchiolitis and follow-up strategies for infants at higher risk of asthma in the future perspective.

Respiratory infections in children born preterm in low and middle-income countries: A systematic review

CONTEXT

Studies from high-income countries indicates that infants born preterm are at increased risk of respiratory infections; however in the low and middle-income countries (LMICs) data are limited. Our aim was to systematically review the studies evaluating the risk of respiratory infections in preterm children born in LMICs.

METHODS

We searched Medline, PubMed, Cumulative Index of Nursing and Allied Health Literature, Embase, and Psych-INFO databases for studies reporting respiratory outcomes in children born preterm in LMICs. Two authors extracted the data and evaluated the risk of bias with appropriate assessment methods independently.

RESULTS

Twelve observational studies evaluating 5969 children were included in the review. The risk of lower respiratory tract infection varied from 5% to 73.9%. Similarly, respiratory syncytial virus (RSV) infection risk ranged from 4.4% to 22.7%. The unadjusted relative risk for any respiratory tract infection or lower respiratory tract infection was significantly higher in the children born preterm than in children born at term (1.52 [95% confidence interval 1.25-1.85]). We also noted wide-ranging risk of respiratory infections requiring in-hospital or emergency care (range: 0.5%-27.7%) and hospital stay in children born preterm (range: 6-14.3 days).

CONCLUSIONS

Preterm-born children in LMICs are at risk of increased respiratory infections compared to term-born children; however, the baseline risk is variable, although substantial; This highlights the need for preventive strategies, including RSV immunoprophylaxis.

Airway Epithelial Cell Junctions as Targets for Pathogens and Antimicrobial Therapy

Intercellular contacts between epithelial cells are established and maintained by the apical junctional complexes (AJCs). AJCs conserve cell polarity and build epithelial barriers to pathogens, inhaled allergens, and environmental particles in the respiratory tract. AJCs consist of tight junctions (TJs) and adherens junctions (AJs), which play a key role in maintaining the integrity of the airway barrier. Emerging evidence has shown that different microorganisms cause airway barrier dysfunction by targeting TJ and AJ proteins. This review discusses the pathophysiologic mechanisms by which several microorganisms (bacteria and viruses) lead to the disruption of AJCs in airway epithelial cells. We present recent progress in understanding signaling pathways involved in the formation and regulation of cell junctions. We also summarize the potential chemical inhibitors and pharmacological approaches to restore the integrity of the airway epithelial barrier. Understanding the AJCs-pathogen interactions and mechanisms by which microorganisms target the AJC and impair barrier function may further help design therapeutic innovations to treat these infections.

Level of maternal antibodies against respiratory syncytial virus (RSV) nucleoprotein at birth and risk of RSV very severe lower respiratory tract infection

BACKGROUND

The nucleoprotein (N protein) of respiratory syncytial virus (RSV) is a candidate antigen for new RSV vaccine development. The aim of the present study was to investigate the association between maternal antibody titers against the RSV N protein at birth and the newborns' risk of developing very severe lower respiratory tract infection (VS-LRTI).

METHODS

In this single-center prospective cohort study, 578 infants born during the RSV epidemic season in France were included. Among these, 36 were hospitalized for RSV VS-LRTI. A generalized linear model was used to test the occurrence of a VS-LRTI in function of sex, mode of delivery, parity of the mother, type of pregnancy, date of birth in relation to the peak of the epidemic, and antibody titer against N protein.

RESULTS

All cord blood samples had detectable antibodies against N protein. The mean titers were significantly lower in newborns with risk factors for RSV severe LRTI (preterm infants, birth before the peak epidemic, multiparous mother). There was no association between antibody titer against the N protein and a protection against VS-LRTI.

CONCLUSIONS

Further studies are needed to support the hypothesis that transfer of maternal antibodies against the RSV N protein can provide a significant immune protection early in infancy and that N protein candidate vaccine may be a suitable target for maternal vaccine.

Clinical and economic burden of respiratory syncytial virus in Spanish children: the BARI study

Respiratory syncytial virus (RSV) infection is a major cause of morbidity in children. However, its disease burden remains poorly understood, particularly outside of the hospital setting. Our study aimed to estimate the burden of medically attended acute lower respiratory infection (ALRI) cases potentially related to RSV in Spanish children. Longitudinal data from September 2017 to June 2018 of 51,292 children aged < 5 years old from the National Healthcare System (NHS) of two Spanish regions were used. Three case definitions were considered: (a) RSV-specific; (b) RSV-specific and unspecified acute bronchiolitis (RSV-specific and Bronchiolitis), and; (c) RSV-specific and unspecified ALRI (RSV-specific and ALRI). A total of 3460 medically attended ALRI cases potentially due to RSV were identified, of which 257 (7.4%), 164 (4.7%), and 3039 (87.8%) coded with RSV-specific, unspecific bronchiolitis, and unspecific ALRI codes, respectively. Medically attended RSV-specific and ALRI cases per 1000 children was 134.4 in the first year of life, 119.4 in the second, and 35.3 between 2 and 5 years old. Most cases were observed in otherwise healthy children (93.1%). Mean direct healthcare cost per medically attended RSV-specific and ALRI case was €1753 in the first year of life, €896 in the second, and €683 between 2 and 5 years old. Hospitalization was the main driver of these costs, accounting for 55.6%, 38.0% and 33.4%, in each respective age group. In RSV-specific cases, mean direct healthcare cost per medically attended case was higher, mostly due to hospitalization: €3362 in the first year of life (72.9% from hospitalizations), €3252 in the second (72.1%), and €3514 between 2 and 5 years old (74.2%). These findings suggest that hospitalization data alone will underestimate the RSV infections requiring medical care, as will relying only on RSV-specific codes. RSV testing and codification must be improved and preventive solutions adopted, to protect all infants, particularly during the first year of life.

Medicinal Fungi with Antiviral Effect

Pandemics from various viruses make natural organisms face challenges over and over again. Therefore, new antiviral drugs urgently need to be found to solve this problem. However, drug research and development is a very difficult task, and finding new antiviral compounds is desirable. A range of medicinal fungi such as Ganoderma lucidum and Cordyceps sinensis are widely used all over the world, and they can enhance human immunity and direct anti-virus activities and other aspects to play an antiviral role. Medicinal fungi are used as foods or as food supplements. In this review, the species of medicinal fungi with antiviral activity in recent decades and the mechanism of antiviral components were reviewed from the perspectives of human, animal, and plant viruses to provide a comprehensive theory based on better clinical utilization of medicinal fungi as antiviral agents.

Bioengineered Co-culture of organoids to recapitulate host-microbe interactions

The recent spike in the instances of complex physiological host-microbe interactions has raised the demand for developing in vitro models that recapitulate the microbial microenvironment in the human body. Organoids are steadily emerging as an in vitro culture system that closely mimics the structural, functional, and genetic features of complex human organs, particularly for better understanding host-microbe interactions. Recent advances in organoid culture technology have become new avenues for assessing the pathogenesis of symbiotic interactions, pathogen-induced infectious diseases, and various other diseases. The co-cultures of organoids with microbes have shown great promise in simulating host-microbe interactions with a high level of complexity for further advancement in related fields. In this review, we provide an overview of bioengineering approaches for microbe-co-cultured organoids. Latest developments in the applications of microbe-co-cultured organoids to study human physiology and pathophysiology are also highlighted. Further, an outlook on future research on bioengineered organoid co-cultures for various applications is presented.

Protein and Peptide Substances in the Treatment of Respiratory Syncytial Infection: Current State

Respiratory syncytial virus infection (RSVI) is an acute medical and social problem in many countries globally. Infection is most dangerous for infants under one year old and the elderly. Despite its epidemiological relevance, only two drugs are registered for clinical use against RSVI: ribavirin (approved in a limited number of countries due to side effects) and palivizumab (Synagis), which is intended only for the prevention, but not the treatment, of infection. Currently, various research groups are searching for new drugs against RSV, with three main areas of research: small molecules, polymeric drugs (proteins and peptides), and plant extracts. This review is devoted to currently developed protein and peptide anti-RSV drugs.

Favipiravir in the Battle with Respiratory Viruses

Abstract:

Among antiviral drugs, the vast majority targets only one or two related viruses. The conventional model, one virus - one drug, significantly limits therapeutic options. Therefore, in the strategy of controlling viral infections, there is a necessity to develop compounds with pleiotropic effects. Favipiravir (FPV) emerged as a strong candidate to become such a drug. The aim of the study is to present up-to-date information on the role of favipiravir in the treatment of viral respiratory infections. The anti-influenza activity of favipiravir has been confirmed in cell culture experiments, animal models and clinical trials. Thoroughly different - from the previously registered drugs - mechanism of action suggests that FVP can be used as a countermeasure for the novel or re-emerging influenza virus infections. In recent months, favipiravir has been broadly investigated due to its potential efficacy in the treatment of Covid-19. Based on preclinical and clinical studies and a recently published meta-analysis it seems that favipiravir may be a promising antiviral drug in the treatment of patients with Covid-19. FPV is also effective against other RNA respiratory viruses and may be a candidate for the treatment of serious infections caused by human rhinovirus, respiratory syncytial virus, metapneumovirus, parainfluenza viruses and hantavirus pulmonary syndrome.

The Differences Between RSV and no RSV Acute Bronchiolitis in Hospitalized Infants: A Cross-Sectional Study

To identify the differences between the RSV and non-RSV bronchiolitis in hospitalized infants in a Greek tertiary pediatric unit and the possible risk factors related to severe forms of the illness. We performed a retrospective cross-sectional data analysis by reviewing medical records of patients that were hospitalized for acute bronchiolitis from 2012 to 2019. The patients with RSV bronchiolitis were found to require antibiotic treatment, IV fluids, adrenaline, and hypertonic saline inhalations more frequently than the non-RSV patients. They also required prolonged hospitalization, especially those that were admitted to PICU, and received oxygen therapy for longer periods. We searched risk factors for severe forms of the disease according to the need for admission to PICU, the supplemental oxygen and the extended length of hospital stay, concurrently. The patients with RSV bronchiolitis developed more severe illness in comparison with patients with bronchiolitis due to other respiratory viruses.

Potential Neurocognitive Symptoms Due to Respiratory Syncytial Virus Infection

Respiratory infections are among the major public health burdens, especially during winter. Along these lines, the human respiratory syncytial virus (hRSV) is the principal viral agent causing acute lower respiratory tract infections leading to hospitalization. The pulmonary manifestations due to hRSV infection are bronchiolitis and pneumonia, where the population most affected are infants and the elderly. However, recent evidence suggests that hRSV infection can impact the mother and fetus during pregnancy. Studies have indicated that hRSV can infect different cell types from the placenta and even cross the placenta barrier and infect the fetus. In addition, it is known that infections during the gestational period can lead to severe consequences for the development of the fetus due not only to a direct viral infection but also because of maternal immune activation (MIA). Furthermore, it has been described that the development of the central nervous system (CNS) of the fetus can be affected by the inflammatory environment of the uterus caused by viral infections. Increasing evidence supports the notion that hRSV could invade the CNS and infect nervous cells, such as microglia, neurons, and astrocytes, promoting neuroinflammation. Moreover, it has been described that the hRSV infection can provoke neurological manifestations, including cognitive impairment and behavioral alterations. Here, we will review the potential effect of hRSV in brain development and the potential long-term neurological sequelae.

Age-Specific Etiology of Severe Acute Respiratory Infections and Influenza Vaccine Effectivity in Prevention of Hospitalization in Russia, 2018-2019 Season

The expansion and standardization of clinical trials, as well as the use of sensitive and specific molecular diagnostics methods, provide new information on the age-specific roles of influenza and other respiratory viruses in development of severe acute respiratory infections (SARI). Here, we present the results of the multicenter hospital-based study aimed to detect age-specific impact of influenza and other respiratory viruses (ORV). The 2018-2019 influenza season in Russia was characterized by co-circulation of influenza A(H1N1)pdm09 and A(H3N2) virus subtypes which were detected among hospitalized patients with SARI in 19.3% and 16.4%, respectively. RSV dominated among ORV (15.1% of total cases and 26.8% in infants aged ≤ 2 years). The most significant SARI agents in intensive care units were RSV and influenza A(H1N1)pdm09 virus, (37.3% and 25.4%, respectively, of PCR-positive cases). Hyperthermia was the most frequently registered symptom for influenza cases. In contrast, hypoxia, decreased blood O₂ concentration, and dyspnea were registered more often in RSV, rhinovirus, and metapneumovirus infection in young children. Influenza vaccine effectiveness (IVE) against hospitalization of patients with PCR-confirmed influenza was evaluated using test-negative case-control design. IVE for children and adults was estimated to be 57.0% and 62.0%, respectively. Subtype specific IVE was higher against influenza A(H1N1)pdm09, compared to influenza A(H3N2) (60.3% and 45.8%, respectively). This correlates with delayed antigenic drift of the influenza A(H1N1)pdm09 virus and genetic heterogeneity of the influenza A(H3N2) population. These studies demonstrate the need to improve seasonal influenza prevention and control in all countries as states by the WHO Global Influenza Strategy for 2019-2030 initiative.

The impact of childhood RSV infection on children's and parents' quality of life: a prospective multicenter study in Spain

Background

 Several immunisation candidates against RSV are in late-stage clinical trials. To evaluate the benefits of a potential vaccination programme, both economic and health benefits will be needed. Health benefits are usually measured in Health-related Quality of Life (HRQoL) loss using standardised questionnaires. However, there are no RSV-specific questionnaires validated for children under 2 years, in whom most RSV episodes occur. Therefore, HRQoL estimates are taken from literature or inadequate tools. We determined HRQoL loss and direct costs due to an RSV episode in children younger than 2 years and their caregivers during a month of follow up, using a new questionnaire administered online.

Methods

 An observational prospective multicentre surveillance study was conducted in children aged younger than two years. Children were recruited from 8 primary care centres and 1 hospital in the Valencia region and Catalonia (Spain). RSV-positive cases were obtained by immunochromatographic test. HRQoL was assessed using a new ad-hoc 38 item-questionnaire developed. Parents of infected children completed 4 questionnaires at four timepoints (day 0, 7, 14 and 30) after diagnosis.

Results

 117 children were enrolled in the study and 86 (73.5%) were RSV + . Median (interquartile range; IQR) scores were 0.52 (0.42–0.68), 0.65 (0.49–0.79), 0.82 (0.68–0.97) and 0.94 (0.81–1), for days 0, 7, 14 and 30, respectively. Compared to total recovery (Q30), HRQoL loss was 37.5%, 31.5% and 8.9% on days 0, 7 and 14 since diagnosis of the disease. The total median cost per patient (including treatments) was €598.8 (IQR: 359.63–2425.85).

Conclusions

 RSV had almost 40% impact on HRQoL during the first week since onset of symptoms and the median cost per episode and patient was about €600. These results represent a substantial input for health-economic evaluations of future RSV-related interventions such as vaccination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06629-z.

Vitamin D in respiratory viral infections: a key immune modulator?

Respiratory viral infections are common respiratory diseases. Influenza viruses, RSV and SARS-COV2 have the potential to cause severe respiratory infections. Numerous studies have shown that unregulated immune response to these viruses can cause excessive inflammation and tissue damage. Therefore, regulating the antiviral immune response in the respiratory tract is of importance. In this regard, recent years studies have emphasized the importance of vitamin D in respiratory viral infections. Although, the most well-known role of vitamin D is to regulate the metabolism of phosphorus and calcium, it has been shown that this vitamin has other important functions. One of these functions is immune regulation. Vitamin D can regulate the antiviral immune response in the respiratory tract in order to provide an effective defense against respiratory viral infections and prevention from excessive inflammatory response and tissue damage. In addition, this vitamin has preventive effects against respiratory viral infections. Some studies during the COVID-19 pandemic have shown that vitamin D deficiency may be associated with a higher risk of mortality and sever disease in patients with COVID-19. Since, more attention has recently been focused on vitamin D. In this article, after a brief overview of the antiviral immune response in the respiratory system, we will review the role of vitamin D in regulating the antiviral immune response comprehensively. Then we will discuss the importance of this vitamin in influenza, RSV, and COVID-19.

Disease Burden Due to Respiratory Syncytial Virus in Indian Pediatric Population: A Literature Review

Respiratory syncytial virus (RSV) is one of the leading causes of lower respiratory tract infections in young children. Globally, there is huge disease burden, high treatment cost, and health impact beyond acute episodes due to RSV which necessitate development and implementation of preventive strategies for the control of RSV infection. The disease burden due to RSV in pediatric population across India is still not clearly understood so this literature review was therefore conducted to gather data on disease burden due to RSV in Indian pediatric population. Systematic literature search was performed using PubMed and Google search with different medical subject headings from 2007 to 2020. Studies performed in Indian pediatric population were selected for review. Literature review revealed that in India, epidemiology of RSV infection is well documented in young children (0-5 years) as compared to children from other age groups. The rates of RSV detection in various studies conducted in younger children (0-5 years) vary from 2.1% to 62.4% in India which is higher as compared to children from other age groups. In India, RSV mainly peaks around rainy to early winter season, that is, during months of June through October while smaller peak was noted during December, January, and February. In 2020, higher RSV-associated disease burden was reported among children (<5 years) in low-income and lower-middle-income countries. Considering significant disease burden due to RSV in young Indian children, availability of RSV vaccine would be crucial to prevent RSV infections in children and its spread in the community.

Clinico demographic profiling of the Respiratory syncytial virus (RSV) infected children admitted in tertiary care hospital in North India

Background:

Acute bronchiolitis is fatal disease involving lower respiratory tract of infants and children of paediatric age group. Respiratory Syncytial Virus (RSV) is responsible for causing more than 70% hospital admissions of children aged less than 2 years thus making a necessity for accurate and timely diagnosis.

Aims:

The main aim of study was clinicodemographic correlation of RSV positive children presenting to our tertiary care hospital.

Setting and Design:

It is a retrospective study done between December to January 2018.

Materials and Methods:

Detection of RSV antigen from nasophyrangeal aspirates using Mouse Monoclonal anti RSV Antibody (by Novatetra) and Goat Anti Mouse Antibody conjugated with FITC as secondary antibody.

Results:

A total of 147 samples were received in the laboratory and 20 were tested as positive for RSV Antigen. Totally, 19/20 children were aged less than 1 year and with a male predominance. The most common symptom was cough and respiratory distress. Eight percent of the children showed wheezing and 18/20 required assisted ventilation. The clinical course in one child deteriorated leading to death of that patient.

Conclusions:

The timely diagnosis and management of RSV infected children is utmost needed to prevent morbidity and mortality. The premorbid conditions can assist to differentiate the viral from bacterial pneumonia and thus enable speedy recovery of the child.

New Look at RSV Infection: Tissue Clearing and 3D Imaging of the Entire Mouse Lung at Cellular Resolution

BACKGROUND

Respiratory Syncytial Virus (RSV) is the major cause of severe acute respiratory tract illness in young children worldwide and a main pathogen for the elderly and immune-compromised people. In the absence of vaccines or effective treatments, a better characterization of the pathogenesis of RSV infection is required. To date, the pathophysiology of the disease and its diagnosis has mostly relied on chest X-ray and genome detection in nasopharyngeal swabs. The development of new imaging approaches is instrumental to further the description of RSV spread, virus-host interactions and related acute respiratory disease, at the level of the entire lung.

METHODS

By combining tissue clearing, 3D microscopy and image processing, we developed a novel visualization tool of RSV infection in undissected mouse lungs.

RESULTS

Whole tissue analysis allowed the identification of infected cell subtypes, based on both morphological traits and position within the cellular network. Furthermore, 3D imaging was also valuable to detect the cytoplasmic viral factories, also called inclusion bodies, a hallmark of RSV infection.

CONCLUSIONS

Whole lung clearing and 3D deep imaging represents an unprecedented visualization method of infected lungs to allow insight into RSV pathophysiology and improve the 2D histology analyses.

The foundation of the Institute of Paediatric Virology on the island of Euboea, Greece (Review)

The Institute of Paediatric Virology, founded on October 2019 on the island of Euboea in Greece, introduces medical students, paediatric and neonatal trainees, postgraduate students, virologists, paediatric and allied health professionals to the bold, new, scientific field of paediatric virology. The institute is committed to medical education and is the sequel of the Paediatric Virology Study Group (PVSG), which was formed in 2007 in the United Kingdom by a group of young paediatric trainees and junior researchers. The main mission of the institute is to provide an educational e-platform on neonatal and paediatric viral infections, to facilitate scientific discussion between virologists and paediatric health professionals and to develop an international network aiming to the promotion of children's health by the prevention and treatment of viral infectious diseases. The foundation of the institute is dedicated to three children from a small fishing village at the south of the island of Euboea in Greece, who survived the 1918 Spanish flu pandemic.