Non-pulmonary manifestations of respiratory syncytial virus infection

Estimated Incidence Rate of Specific Types of Cardiovascular and Respiratory Hospitalizations Attributable to Respiratory Syncytial Virus Among Adults in Germany Between 2015 and 2019

BACKGROUND

RSV incidence in adults is frequently underestimated due to non-specific symptomatology, limited standard-of-care testing, and lower test sensitivity compared to infants. We conducted a retrospective observational study to estimate RSV-attributable incidence of specific types of cardiorespiratory hospitalizations among adults in Germany between 2015 and 2019.

METHODS

Information on hospitalizations and the number of people at risk of hospitalization (denominator) was gathered from a Statutory Health Insurance database. A quasi-Poisson regression model accounting for periodic and aperiodic time trends and virus activity was fitted to estimate the RSV-attributable incidence rate (IR) of four specific cardiovascular hospitalizations (arrhythmia, ischemic heart diseases, chronic heart failure exacerbations, and cerebrovascular diseases) and four specific respiratory hospitalizations (influenza/pneumonia, bronchitis/bronchiolitis, chronic lower respiratory tract diseases, and upper respiratory tract diseases).

RESULTS

The estimated RSV-attributable IRs of hospitalizations generally increased with age. Among estimated cardiovascular hospitalizations in adults aged ≥ 60 years, arrhythmia and ischemic heart diseases accounted for the highest incidence of RSV-attributable events, followed by chronic heart failure exacerbation, with annual IR ranges of 157-260, 133-214, and 105-169 per 100,000 person-years, respectively. The most frequent RSV-attributable respiratory hospitalizations in adults aged ≥ 60 years were estimated for chronic lower respiratory tract diseases and bronchitis/bronchiolitis, with annual IR ranges of 103-168 and 77-122 per 100,000 person-years, respectively.

CONCLUSIONS

RSV causes a considerable burden of respiratory and cardiovascular hospitalizations in adults in Germany, similar to other respiratory viruses (e.g., influenza and SARS-CoV-2). This highlights the need to implement effective prevention strategies, especially for older adults.

Clinical manifestations, para-clinical features and outcome of Iranian adults with respiratory syncytial virus (RSV) infection: a report from hospitalized patients

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of children's pulmonary infections. However, there are fewer studies on RSV infections in adults. The purpose of this study was to describe the clinical manifestations, para-clinical characteristics, and outcome of RSV infection among adult patients who were referred to the Imam Khomeini Hospital Complex during the winter and spring of 2022-2023.

METHODS

From December 21, 2022, to May 20, 2023, we conducted a cross-sectional study on hospitalized adults having positive RT-PCR results for RSV. We further assessed the clinical and para-clinical characteristics and outcomes of the RSV groups.

RESULTS

We screened 1375 adults with suspected acute respiratory infections (ARIs) and confirmed RSV infections in 59 of them (4.3%). Of these, 23 patients were excluded from further analysis due to outpatient management, leaving 36 hospitalized patients with confirmed RSV infection (61.01%). The mean age of the hospitalized patients was 53.28 ± 20.37 years (range: 15-83), with a slightly higher proportion of females (52.80%) compared to males (47.20%). Dyspnea, productive cough, and fever were the most common symptoms, with a mean symptom duration of 10.50 days. Ischemic heart disease, hypertension, and liver failure were common underlying conditions. Notably, biochemical and inflammatory markers such as CRP, ESR, and LDH were significantly elevated beyond the normal range. Finally, five patients (13.9%) who received intensive care treatments died.

CONCLUSIONS

Although the rate of RSV infection was not high among Iranian adults, a greater proportion of patients required hospitalization (61%). There was a significant link between liver failure, an elevated INR, more than 30% bilateral pulmonary involvement, abdominal pain, longer ICU stays, and immunodeficiency cases with increased mortality from RSV infection. We suggest that RSV infection may act as a secondary factor in decompensating pre-existing liver failure, which was present in certain patients with underlying conditions, potentially leading to life-threatening consequences.

The Role of the CX3CR1-CX3CL1 Axis in Respiratory Syncytial Virus Infection and the Triggered Immune Response

Respiratory syncytial virus (RSV) is a common respiratory pathogen that causes respiratory illnesses, ranging from mild symptoms to severe lower respiratory tract infections in infants and older adults. This virus is responsible for one-third of pneumonia deaths in the pediatric population; however, there are currently only a few effective vaccines. A better understanding of the RSV-host relationship at the molecular level may lead to a more effective management of RSV-related symptoms. The fractalkine (CX3CL1) receptor (CX3CR1) is a co-receptor for RSV expressed by airway epithelial cells and diverse immune cells. RSV G protein binds to the CX3CR1 receptor via a highly conserved amino acid motif (CX3C motif), which is also present in CX3CL1. The CX3CL1-CX3CR1 axis is involved in the activation and infiltration of immune cells into the infected lung. The presence of the RSV G protein alters the natural functions of the CX3CR1-CX3CL1 axis and modifies the host's immune response, an aspects that need to be considered in the development of an efficient vaccine and specific pharmacological treatment.

Epidemiology of Respiratory Syncytial Virus-Associated Acute Lower Respiratory Tract Infection among Hospitalized Under-5s in Northwestern Nigeria

Objective Globally, 33 million cases of respiratory syncytial virus (RSV) infections occur annually among under-fives (5s). Ninety-nine percent of deaths from RSV occur in low- and middle-income countries. Under-five pneumonia mortality in Nigeria was estimated at 140,520 in 2017, but RSV epidemiological data are scant due to poor awareness and limited testing. Vaccines for RSV are currently under development and RSV mortality data from this high mortality, low resource setting are essential to maximizing the potential benefit of vaccination as well as promoting vaccine uptake. This study aimed to describe the epidemiology of RSV-associated acute lower respiratory tract infection (ALRTI) in children younger than 5 years in Zaria, Northwestern Nigeria.

Methods A prospective cohort study was conducted among children aged 1 month to 5 years who were hospitalized with ALRTI in the Emergency Pediatric Unit of a tertiary hospital in Zaria from November 2018 to October 2019. Naso-pharyngeal swabs were obtained for RSV testing using a point-of-care immunoassay technique.

Results Thirty-three percent (35/106) of the children had RSV-related ALRTI. The median age of RSV-positive cases was 8 months (IQR 3–14). Two-thirds of children (68.6%, 24/35) were below 12 months. The RSV mortality rate was 5.7% (2/35). RSV occurred in 10 months of the year with peaks in March and July.

Conclusion A third of admitted children with ALRTI were positive for RSV. Therefore RSV significantly contributes to childhood pneumonia and the dual seasonal peak observed in our study may have implications for vaccine implementation.

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.

Bivalirudin exerts antiviral activity against respiratory syncytial virus-induced lung infections in neonatal mice

Respiratory syncytial virus (RSV) is the most common cause of small airways inflammation in the lungs (bronchiolitis) in neonates and immunocompromised adults. The deregulation of cellular and plasma components leads to increased morbidity and mortality. The activation of the clotting cascade plays a key role in the progression of disease severity during viral infection. The current investigation studied the effect of bivalirudin (BR) on the progression and cellular effects of RSV-induced infection in the neonatal mice model. Mice (5-7 days old) were inoculated intranasally with RSV with or without BR administration (2 mg kg^-1 day^-1, i.v.) for 2 weeks. Tissue histopathology, inflammatory signalling genes such as TLR, and cytokines were analyzed. The results showed pneumocytes exhibiting nuclear pyknosis, cellular infiltration in lung tissue and increased lung titers in RSV-infected mice compared to the control. Furthermore, RSV-infected mice demonstrated altered clotting parameters such as D-dimer, soluble thrombomodulin, and increased inflammatory cytokines IL-5, 6, IFN-γ, IL-13, and CXCL1. Additionally, the mRNA expression analysis displayed increased levels of IL-33, TLR3, and TLR7 genes in RSV-infected lung tissue. Further, to delineate the role of micro RNAs, the qRT-PCR analysis was done, and the results displayed an increase in miR-136, miR-30b, and let-7i. At the same time, the down-regulated expression of miR-221 in RSV-infected mice compared to the control. BR treatment reduced the cellular infiltration with reduced inflammatory cytokines and normalized clotting indices. Thus, the study shows that RSV infection induces specific changes in lung tissue and the clotting related signalling mechanism. Additionally, BR treatment significantly reduces bronchiolitis and prevents the severity of the infections suggesting that BR can possibly be used to reduce the viral-mediated infections in neonates.

Nonrespiratory sites of influenza-associated disease: mechanisms and experimental systems for continued study

The productive replication of human influenza viruses is almost exclusively restricted to cells in the respiratory tract. However, a key aspect of the host response to viral infection is the production of inflammatory cytokines and chemokines that are not similarly tissue restricted. As such, circulating inflammatory mediators, as well as the resulting activated immune cells, can induce damage throughout the body, particularly in individuals with underlying conditions. As a result, more holistic experimental approaches are required to fully understand the pathogenesis and scope of influenza virus-induced disease. This review summarizes what is known about some of the most well-appreciated nonrespiratory tract sites of influenza virus-induced disease, including neurological, cardiovascular, gastrointestinal, muscular and fetal developmental phenotypes. In the context of this discussion, we describe the in vivo experimental systems currently being used to study nonrespiratory symptoms. Finally, we highlight important future questions and potential models that can be used for a more complete understanding of influenza virus-induced disease.

Endothelial Dysfunction through Oxidatively Generated Epigenetic Mark in Respiratory Viral Infections

The bronchial vascular endothelial network plays important roles in pulmonary pathology during respiratory viral infections, including respiratory syncytial virus (RSV), influenza A(H1N1) and importantly SARS-Cov-2. All of these infections can be severe and even lethal in patients with underlying risk factors.A major obstacle in disease prevention is the lack of appropriate efficacious vaccine(s) due to continuous changes in the encoding capacity of the viral genome, exuberant responsiveness of the host immune system and lack of effective antiviral drugs. Current management of these severe respiratory viral infections is limited to supportive clinical care. The primary cause of morbidity and mortality is respiratory failure, partially due to endothelial pulmonary complications, including edema. The latter is induced by the loss of alveolar epithelium integrity and by pathological changes in the endothelial vascular network that regulates blood flow, blood fluidity, exchange of fluids, electrolytes, various macromolecules and responses to signals triggered by oxygenation, and controls trafficking of leukocyte immune cells. This overview outlines the latest understanding of the implications of pulmonary vascular endothelium involvement in respiratory distress syndrome secondary to viral infections. In addition, the roles of infection-induced cytokines, growth factors, and epigenetic reprogramming in endothelial permeability, as well as emerging treatment options to decrease disease burden, are discussed.

The burden of respiratory syncytial virus associated with acute lower respiratory tract infections in Chinese children: a meta-analysis

BACKGROUND

Respiratory syncytial virus (RSV), which is associated with acute lower respiratory tract infection (ALRTI), is highly common among children. The burden of RSV varies between countries. In China, the actual burden remains unclear. Thus, this meta-analysis aimed to quantify the positive rate of ALRTI-related RSV infections among Chinese children in recent years.

METHODS

The PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, and Chinese BioMedical (CBM) databases were searched to identify relevant cross-sectional studies published between January 1, 2015 and December 31, 2018. Subsequently, a meta-analysis was performed using R software.

RESULTS

A total of 18 studies involving 66,799 ALRTI cases were finally included in the meta-analysis. Among those ALRTIs cases, the overall positive rate of RSV infection was 16.0% (95% CI: 12.9-19.6%). The rate was significantly higher in children <3 years (19.5%, 95% CI 13.3-27.6%) compared to those ≥3 years (5.6%, 95% CI: 2.3-13.2%; P<0.01). Moreover, stratified analysis revealed that RSV infection was most frequent in children <6 months (31.1%, 95% CI: 21.0-43.5%). The positive detection rate of RSV infection was significantly associated with season (P<0.01), with winter having the highest detection rate (29.0%, 95% CI: 21.3-38.2%), followed by autumn (20.9%, 95% CI: 10.5-37.3%), and summer having the lowest rate (6.4%, 95% CI: 2.3-16.9%). The rate of RSV infection was highest and lowest in November (49.4%, 95% CI: 29.0-70.0%) and June (1.3%, 95% CI: 0.6-2.8%), respectively. When stratified according to geographical region, RSV infections peaked in winter (South: 24.8%, 95% CI: 12.9-42.3%; North: 36.3%, 95% CI: 30.8-42.1%), followed by autumn (South: 13.9%, 95% CI: 6.5-27.4%; North: 32.7%, 95% CI: 20.2-48.3%).

CONCLUSIONS

In conclusion, our meta-analysis showed that among Chinese children with ALRTI, 16.0% had RSV infection. RSV infection frequently occurred in children under the age of 3 years, especially in those under 6 months. The rate of RSV infections was highest in winter, followed by autumn.