Respiratory Syncytial Virus Infection: An Illness for All Ages

Longitudinal humoral analysis in RSV-infected infants identifies pre-existing RSV strain-specific G and evolving cross-reactive F antibodies

Respiratory syncytial virus (RSV) is among the most common causes of lower respiratory tract infection (LRTI) and hospitalization in infants. However, the mechanisms of immune control in infants remain incompletely understood. Antibody profiling against attachment (G) and fusion (F) proteins in children less than 2 years of age, with mild (outpatients) or severe (inpatients) RSV disease, indicated substantial age-dependent differences in RSV-specific immunity. Maternal antibodies were detectable for the first 3 months of life, followed by a long window of immune vulnerability between 3 and 6 months and a rapid evolution of FcγR-recruiting immunity after 6 months of age. Acutely ill hospitalized children exhibited lower G-specific antibodies compared with healthy controls. With disease resolution, RSV-infected infants generated broad functional RSV strain-specific G-responses and evolved cross-reactive F-responses, with minimal maternal imprinting. These data suggest an age-independent RSV G-specific functional humoral correlate of protection, and the evolution of RSV F-specific functional immunity with disease resolution.

Burden of respiratory syncytial virus in older adults in Taiwan: An expert perspective on knowledge gaps

The burden of respiratory syncytial virus (RSV) infection among older adults in Taiwan is not well understood due to a scarcity of published epidemiological data. Nonetheless, the increasing proportion of older adults is anticipated to translate to increased burden of RSV infection, presenting a challenge to the healthcare system. Thus, an expert meeting was convened among a panel of infectious disease specialists from Taiwan to evaluate the existing local evidence and data gaps related to RSV infection in older adults (aged ≥50 years), and propose steps to generating evidence on disease burden among this population. Overall, there are few studies on the clinical and economic burden of RSV infection in Taiwan, and existing data are limited by small sample sizes and highly selected populations. Inconsistent RSV testing practices among older adults contribute to under-diagnosis and under-reporting, driven by limitations to reimbursement policies that discourage proactive RSV testing in older adults, and the lack of appropriate, targeted RSV treatment. Crucially, the paucity of epidemiological data may perpetuate a lack of awareness of RSV among clinicians and the public, hinder investments into RSV testing at a policymaker level, and thereby impede implementation of consistent diagnostic practices, precluding a deeper understanding of RSV. To overcome these challenges, it is imperative to prioritize generation of epidemiological data to establish the burden of RSV infection among older adults in Taiwan. Such data would also support a multi-stakeholder group in assessing the impact of future RSV-related interventions, such as educational initiatives and preventative strategies including vaccines.

Engineered dityrosine-bonding of the RSV prefusion F protein imparts stability and potency advantages

Viral fusion proteins facilitate cellular infection by fusing viral and cellular membranes, which involves dramatic transitions from their pre- to postfusion conformations. These proteins are among the most protective viral immunogens, but they are metastable which often makes them intractable as subunit vaccine targets. Adapting a natural enzymatic reaction, we harness the structural rigidity that targeted dityrosine crosslinks impart to covalently stabilize fusion proteins in their native conformations. We show that the prefusion conformation of respiratory syncytial virus fusion protein can be stabilized with two engineered dityrosine crosslinks (DT-preF), markedly improving its stability and shelf-life. Furthermore, it has 11X greater potency as compared with the DS-Cav1 stabilized prefusion F protein in immunogenicity studies and overcomes immunosenescence in mice with simply a high-dose formulation on alum.

Respiratory Syncytial Virus Vaccination Recommendations for Adults Aged 60 Years and Older: The NeumoExperts Prevention Group Position Paper

Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in adults, particularly older adults and those with underlying medical conditions. Vaccination has emerged as a potential key strategy to prevent RSV-related morbidity and mortality. This Neumoexperts Prevention (NEP) Group scientific paper aims to provide an evidence-based positioning and RSV vaccination recommendations for adult patients. We review the current literature on RSV burden and vaccine development and availability, emphasising the importance of vaccination in the adult population. According to our interpretation of the data, RSV vaccines should be part of the adult immunisation programme, and an age-based strategy should be preferred over targeting high-risk groups. The effectiveness and efficiency of this practice will depend on the duration of protection and the need for annual or more spaced doses. Our recommendations should help healthcare professionals formulate guidelines and implement effective vaccination programmes for adult patients at risk of RSV infection now that specific vaccines are available.

Management of Acute Bronchiolitis in Spoke Hospitals in Northern Italy: Analysis and Outcome

Bronchiolitis is an acute viral infection of the lower respiratory tract that affects infants and young children. Respiratory syncytial virus (RSV) is the most common causative agent; however, other viruses can be involved in this disease. We retrospectively reviewed the clinical features of infants aged less than 12 months hospitalized for acute bronchiolitis in our Pediatric Units of Chivasso, Cirié, and Ivrea in Piedmont, Northern Italy, over two consecutive bronchiolitis seasons (September 2021-March 2022 and September 2022-March 2023). Patient-, disease-, and treatment-related variables were analyzed. The probability of therapeutic success (discharge home) was 96% for all patients (93% for RSV vs. 98% for non-RSV patients, p > 0.05). Among 192 patients, 42 infants (22%) underwent high-flow oxygen support (HFNC), and only 8 (4%) needed to be transferred to our hub referral hospital. Factors associated with hub hospital transfer were the age under 1 month and the failure of HFNC. The wide and increasing use of HFNC in pediatric inpatients improved the management of bronchiolitis in Spoke hospitals, reducing transfer to a hub hospital provided with Intensive Care Units.

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.

[After the COVID-19 pandemic-Which new vaccinations for adults are available or coming soon?]

The accumulation of respiratory infections in the winter months repeatedly highlights the relevance of prevention through vaccination, even beyond a pandemic. Current developments in this field are therefore highly relevant, particularly for older people who are more susceptible to infections due to immune senescence and comorbidities. The Standing Committee on Vaccination (STIKO) has responded accordingly by recommending the 20-valent pneumococcal conjugate vaccine PCV20 for standard and indication vaccination of adults. Furthermore, new vaccines against respiratory syncytial virus (RSV) infections are available for which the STIKO has not yet issued a recommendation. The development of other more effective and more immunogenic vac2cines is being driven in particular by new technologies, such as mRNA or vector vaccines. Various higher valent pneumococcal vaccine candidates and, for example, universal influenza vaccines are also already in development.

Low peripheral blood chemokine (C-C motif) ligand 5 and tumor necrosis factor α gene expression is associated with unfavorable progression of respiratory syncytial virus bronchiolitis in infants

OBJECTIVES

We aimed to analyze whether the expression of inflammatory and antiviral genes in respiratory syncytial virus (RSV)-infected infants' peripheral blood is associated with bronchiolitis progression.

METHODS

We conducted a prospective study on 117 infants between 2015 and 2023. The expression levels of nine genes were quantified by quantitative polymerase chain reaction. Infants were classified according to their clinical evolution during hospital admission: (i) non-progression (n = 74), when the RSV bronchiolitis severity remained stable or improved; (ii) unfavorable progression (n = 43), when the RSV bronchiolitis severity increased. The association analysis was performed by logistic regression, adjusted by age, gender, prematurity, and RSV bronchiolitis severity in the emergency room.

RESULTS

Infants were 57.3% male, and the median age of the study population was 61 days. Thirty-five infants (30.7%) were admitted to the intensive care unit after hospital admission. Univariate logistic models showed that tumor necrosis factor (TNFα) and chemokine (C-C motif) ligand (CCL5) gene expression at baseline were inversely associated with unfavorable progression, which was confirmed by multivariate analyses: TNFα (adjusted odds ratio = 0.8 [95% confidence interval = 0.64-0.99], P-value = 0.038) and CCL5 (adjusted odds ratio = 0.76 [95% confidence interval = 0.62-0.93], P-value = 0.007).

CONCLUSIONS

An inadequate immune response to RSV, characterized by reduced gene expression levels of CCL5 and TNFα in peripheral blood, was associated with an unfavorable progression of RSV bronchiolitis.

Efficacy and Safety of Palivizumab as a Prophylaxis for Respiratory Syncytial Virus (RSV) Disease: An Updated Systemic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the current evidence regarding the efficacy and safety of palivizumab as a prophylaxis for respiratory syncytial virus (RSV) disease. We searched MEDLINE via PubMed, Scopus, Cochrane, Web of Science, Embase, and Science Direct from inception till November 2023. Studies that assessed the efficacy and safety of palivizumab in infants aged between 28 days and three months of age were included. We analyzed the data using Review Manager 5.4 software, with results pooled across studies and expressed as risk ratios (RR) with 95% confidence intervals (CI). A total of 10 studies were included. The effect estimates favored palivizumab over placebo regarding the hospitalization for RSV infection (RR=0.51, 95% CI: 0.40 to 0.65; P<0.00001) and ICU admission (RR=0.49, 95% CI: 0.30 to 0.81; P=0.005). On the other hand, the effect estimate showed no significant difference between palivizumab and placebo regarding all-cause mortality (RR=0.69, 95% CI: 0.42 to 1.15; P=0.16), lower respiratory tract infection (RR=0.42, 95% CI: 0.11 to 1.69; P=0.22), and need for mechanical ventilation (RR=0.75, 95% CI: 0.34 to 1.67; P=0.48). Palivizumab can be considered a prophylaxis for RSV disease in young children as it is safe, well-tolerated, and effective in reducing RSV hospitalizations. However, further research through high-quality randomized controlled trials is required to determine its efficacy as a therapeutic agent for established RSV infections.

Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances

Before the COVID-19 pandemic, common community-acquired seasonal respiratory viruses (CARVs) were a significant threat to the health and well-being of allogeneic hematopoietic cell transplant (allo-HCT) recipients, often resulting in severe illness and even death. The pandemic has further highlighted the significant risk that immunosuppressed patients, including allo-HCT recipients, face when infected with SARS-CoV-2. As preventive transmission measures are relaxed and CARVs circulate again among the community, including in allo-HSCT recipients, it is crucial to understand the current state of knowledge, gaps, and recent advances regarding CARV infection in allo-HCT recipients. Urgent research is needed to identify seasonal respiratory viruses as potential drivers for future pandemics.

TNFAIP3-interacting protein 1 polymorphisms and their association with symptomatic human respiratory syncytial virus infection and bronchiolitis in infants younger than one year from South Africa: A case-control study

OBJECTIVES

This study analyzed the association of TNFAIP3-interacting protein 1 (TNIP1) polymorphisms with the symptomatic human respiratory syncytial virus (HRSV) infection and bronchiolitis in infants.

METHODS

A case-control study was conducted involving 129 hospitalized infants with symptomatic HRSV infection (case group) and 161 healthy infants (control group) in South Africa (2016-2018). Six TNIP1 polymorphisms (rs869976, rs4958881, rs73272842, rs3792783, rs17728338, and rs999011) were genotyped. Genetic associations were evaluated using logistic regression adjusted by age and gender.

RESULTS

Both rs73272842 G and rs999011 C alleles were associated with reduced odds for symptomatic HRSV infection (adjusted odd ratio [aOR] = 0.68 [95% confidence interval {CI} = 0.48-0.96] and aOR = 0.36 [95% CI = 0.19-0.68], respectively] and bronchiolitis (aOR = 0.71 [95% CI = 0.50-1.00] and aOR = 0.38 [95% CI = 0.22-0.66], respectively). The significance of these associations was validated using the BCa Bootstrap method (P <0.05). The haplotype GC (composed of rs73272842 and rs999011) was associated with reduced odds of symptomatic HRSV infection (aOR = 0.53 [95% CI = 0.37-0.77]) and bronchiolitis (aOR = 0.62 [95% CI = 0.46-0.84]), which were validated by the BCa Bootstrap method (P = 0.002 for both).

CONCLUSION

TNIP1 rs73272842 G allele and rs999011 C allele were associated with reduced odds of symptomatic HRSV infection and the development of bronchiolitis in infants, suggesting that TNIP1 polymorphisms could impact susceptibility to HRSV illness.

PD-1 Impairs CD8+ T Cell Granzyme B Production in Aged Mice during Acute Viral Respiratory Infection

CD8+ T cell dysfunction contributes to severe respiratory viral infection outcomes in older adults. CD8+ T cells are the primary cell type responsible for viral clearance. With increasing age, CD8+ T cell function declines in conjunction with an accumulation of cytotoxic tissue-resident memory (TRM) CD8+ T cells. We sought to elucidate the role of PD-1 signaling on aged CD8+ T cell function and accumulation of CD8+ TRM cells during acute viral respiratory tract infection, given the importance of PD-1 regulating CD8+ T cells during acute and chronic infections. PD-1 blockade or genetic ablation in aged mice yielded improved CD8+ T cell granzyme B production comparable to that in young mice during human metapneumovirus and influenza viral infections. Syngeneic transplant and adoptive transfer strategies revealed that improved granzyme B production in aged Pdcd1-/- CD8+ T cells was primarily cell intrinsic because aged wild-type CD8+ T cells did not have increased granzyme B production when transplanted into a young host. PD-1 signaling promoted accumulation of cytotoxic CD8+ TRM cells in aged mice. PD-1 blockade of aged mice during rechallenge infection resulted in improved clinical outcomes that paralleled reduced accumulation of CD8+ TRM cells. These findings suggest that PD-1 signaling impaired CD8+ T cell granzyme B production and contributed to CD8+ TRM cell accumulation in the aged lung. These findings have implications for future research investigating PD-1 checkpoint inhibitors as a potential therapeutic option for elderly patients with severe respiratory viral infections.

Human Metapneumovirus Reinfection in Aged Mice Recapitulates Increased Disease Severity in Elderly Humans Infected with Human Metapneumovirus

Human metapneumovirus (HMPV) is a leading cause of respiratory infection in adults >65 y. Nearly all children worldwide are seropositive for HMPV by age 5 y, but reinfections occur throughout life, and there is no licensed vaccine. Recurrent HMPV infection is mild and self-resolving in immunocompetent individuals. However, elderly individuals develop severe respiratory disease on HMPV reinfection that leads to a high risk for morbidity and mortality. In this study, we developed a mouse model to mirror HMPV reinfection in elderly humans. C57BL/6J mice were infected with HMPV at 6-7 wk old, aged in-house, and rechallenged with high-dose virus at 70 wk. Aged rechallenged mice had profound weight loss similar to primary infected mice, increased lung histopathology, and accumulated cytotoxic CD8+CD44+CD62L-CD69+CD103+ memory cells despite having undetectable lung virus titer. When aged mice 14 mo postinfection (p.i.) or young mice 5 wk p.i. were restimulated with HMPV cognate Ag to mimic epitope vaccination, aged mice had an impaired CD8+ memory response. Convalescent serum transfer from young naive or 5 wk p.i. mice into aged mice on day of infection did not protect. Aged mice vaccinated with UV-inactivated HMPV also exhibited diminished protection and poor CD8+ memory response compared with young mice. These results suggest aged individuals with HMPV reinfection have a dysregulated CD8+ memory T cell response that fails to protect and exacerbates disease. Moreover, aged mice exhibited a poor memory response to either epitope peptide or UV-inactivated vaccination, suggesting that aged CD8+ T cell dysfunction presents a barrier to effective vaccination strategies.

The Efficiency of p27 Cleavage during In Vitro Respiratory Syncytial Virus (RSV) Infection Is Cell Line and RSV Subtype Dependent

Respiratory syncytial virus (RSV) fusion protein (F) is highly conserved between subtypes A and B (RSV/A and RSV/B). To become fully active, F precursor undergoes enzymatic cleavage to yield F1 and F2 subunits and releases a 27-amino-acid peptide (p27). Virus-cell fusion occurs when RSV F undergoes a conformational change from pre-F to post-F. Previous data show that p27 is detected on RSV F, but questions remain regarding if and how p27 affects the conformation of mature RSV F. Monoclonal antibodies against p27, site Ø (pre-F specific), and site II were used to monitor RSV F conformation by enzyme-linked immunosorbent assay (ELISA) and imaging flow cytometry. Pre-F to post-F conformational change was induced by a temperature stress test. We found that p27 cleavage efficiency was lower on sucrose-purified RSV/A (spRSV/A) than on spRSV/B. In addition, cleavage of RSV F was cell line dependent: HEp-2 cells had higher retention of p27 than did A549 cells when infected with RSV. Higher levels of p27 were also found on RSV/A-infected cells than on RSV/B-infected cells. We observed that RSV/A F with higher p27 levels could better sustain the pre-F conformation during the temperature stress challenge in both spRSV- and RSV-infected cell lines. Our findings suggest that despite F sequence similarity, p27 of RSV subtypes was cleaved with different efficiencies, which were also dependent on the cell lines used for infection. Importantly, the presence of p27 was associated with greater stability of the pre-F conformation, supporting the possibility that RSV has more than one mechanism for fusion to the host cell. IMPORTANCE RSV fusion protein (F) plays an important role in entry and viral fusion to the host cell. The F undergoes proteolytic cleavages releasing a 27-amino-acid peptide (p27) to become fully functional. The role of p27 in viral entry and the function of the partially cleaved F containing p27 has been overlooked. p27 is thought to destabilize the F trimers, and thus, there is need for a fully cleaved F. In this study, we detected p27 on purified RSV virions and on the surface of virus-infected HEp-2 and A549 cells for circulating RSV strains of both subtypes. Higher levels of partially cleaved F containing p27 better sustained the pre-F conformation during the temperature stress challenge. Our findings highlight that the cleavage efficiency of p27 is different between RSV subtypes and among cell lines and that the presence of p27 contributes to the stability of the pre-F conformation.

Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults

BACKGROUND

Respiratory syncytial virus (RSV) infection causes considerable illness in older adults. The efficacy and safety of an investigational bivalent RSV prefusion F protein-based (RSVpreF) vaccine in this population are unknown.

METHODS

In this ongoing, phase 3 trial, we randomly assigned, in a 1:1 ratio, adults (≥60 years of age) to receive a single intramuscular injection of RSVpreF vaccine at a dose of 120 μg (RSV subgroups A and B, 60 μg each) or placebo. The two primary end points were vaccine efficacy against seasonal RSV-associated lower respiratory tract illness with at least two or at least three signs or symptoms. The secondary end point was vaccine efficacy against RSV-associated acute respiratory illness.

RESULTS

At the interim analysis (data-cutoff date, July 14, 2022), 34,284 participants had received RSVpreF vaccine (17,215 participants) or placebo (17,069 participants). RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). The incidence of local reactions was higher with vaccine (12%) than with placebo (7%); the incidences of systemic events were similar (27% and 26%, respectively). Similar rates of adverse events through 1 month after injection were reported (vaccine, 9.0%; placebo, 8.5%), with 1.4% and 1.0%, respectively, considered by the investigators to be injection-related. Severe or life-threatening adverse events were reported in 0.5% of vaccine recipients and 0.4% of placebo recipients. Serious adverse events were reported in 2.3% of participants in each group through the data-cutoff date.

CONCLUSIONS

RSVpreF vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥60 years of age), without evident safety concerns. (Funded by Pfizer; RENOIR ClinicalTrials.gov number, NCT05035212; EudraCT number, 2021-003693-31.).

Summarizing Study Characteristics and Diagnostic Performance of Commercially Available Tests for Respiratory Syncytial Virus: A Scoping Literature Review in the COVID-19 Era

BACKGROUND

Nonpharmaceutical interventions to prevent the spread of coronavirus disease 2019 also decreased the spread of respiratory syncytial virus (RSV) and influenza. Viral diagnostic testing in patients with respiratory tract infections (RTI) is a necessary tool for patient management; therefore, sensitive and specific tests are required. This scoping literature review aimed to summarize the study characteristics of commercially available sample-to-answer RSV tests.

CONTENT

PubMed and Embase were queried for studies reporting on the diagnostic performance of tests for RSV in patients with RTI (published January 2005-January 2021). Information on study design, patient and setting characteristics, and published diagnostic performance of RSV tests were extracted from 77 studies that met predefined inclusion criteria. A literature gap was identified for studies of RSV tests conducted in adult-only populations (5.3% of total subrecords) and in outpatient (7.5%) or household (0.8%) settings. Overall, RSV tests with analytical time >30 min had higher published sensitivity (62.5%-100%) vs RSV tests with analytical time ≤30 min (25.7%-100%); this sensitivity range could be partially attributed to the different modalities (antigen vs molecular) used. Molecular-based rapid RSV tests had higher published sensitivity (66.7%-100%) and specificity (94.3%-100%) than antigen-based RSV tests (sensitivity: 25.7%-100%; specificity:80.3%-100%).

SUMMARY

This scoping review reveals a paucity of literature on studies of RSV tests in specific populations and settings, highlighting the need for further assessments. Considering the implications of these results in the current pandemic landscape, the authors preliminarily suggest adopting molecular-based RSV tests for first-line use in these settings.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Young Zambian infants with symptomatic RSV and pertussis infections are frequently prescribed inappropriate antibiotics: a retrospective analysis

Pediatric community-acquired pneumonia (CAP) remains a pressing global health concern, particularly in low-resource settings where diagnosis and treatment rely on empiric, symptoms-based guidelines such as the WHO's Integrated Management of Childhood Illness (IMCI). This study details the delivery of IMCI-based health care to 1,320 young infants and their mothers in a low-resource urban community in Lusaka, Zambia during 2015. Our Southern Africa Mother Infant Pertussis Study (SAMIPS) prospectively monitored a cohort of mother/infant pairs across infants' first four months of life, recording symptoms of respiratory infection and antibiotics prescriptions (predominantly penicillins), and tested nasopharyngeal (NP) samples for respiratory syncytial virus (RSV) and Bordetella pertussis. Our retrospective analysis of the SAMIPS cohort found that symptoms and antibiotics use were more common in infants (43% and 15.7%) than in mothers (16.6% and 8%), while RSV and B. pertussis were observed at similar rates in infants (2.7% and 32.5%) and mothers (2% and 35.5%), albeit frequently at very low levels. In infants, we observed strong associations between symptoms, pathogen detection, and antibiotics use. Critically, we demonstrate that non-macrolide antibiotics were commonly prescribed for pertussis infections, some of which persisted across many weeks. We speculate that improved diagnostic specificity and/or clinician education paired with timely, appropriate treatment of pertussis could substantially reduce the burden of this disease while reducing the off-target use of penicillins.

Analysis of Template Variations on RNA Synthesis by Respiratory Syncytial Virus Polymerase

Respiratory syncytial virus (RSV) is a significant threat to infants and elderly individuals globally. Currently, there are no effective therapies or treatments for RSV infection because of an insufficient understanding of the RSV viral machinery. In this study, we investigated the effects of the template variations on RNA synthesis by the RSV polymerase through in vitro RNA synthesis assays. We confirmed the previously reported back-priming activity of the RSV polymerase, which is likely due to the secondary structure of the RNA template. We found that the expansion of the hairpin loop size of the RNA template abolishes the RSV polymerase back-priming activity. At the same time, it seemingly does not affect the de novo RNA synthesis activities of the RSV polymerase. Interestingly, our results show that the RSV polymerase also has a new primer-based terminal extension activity that adds nucleotides to the template and primer in a nonspecific manner. We also mapped the impact of the RNA 5' chemical group on its mobility in a urea-denaturing RNA gel shift assay. Overall, these results enhance our knowledge about the RNA synthesis processes of the RSV polymerase and may guide future therapeutic efforts to develop effective antiviral drugs for RSV treatment.

Virus reduction neutralization test and LI-COR microneutralization assay bridging and WHO international standard calibration studies for respiratory syncytial virus

Background: Respiratory syncytial virus (RSV) vaccine is an unmet medical need. The virus reduction neutralization test (VRNT) was developed to replace the LI-COR microneutralization assay to measure RSV neutralization titers. Methods: A bridging study using selected V171 phase I samples and calibration studies using the WHO international standard antiserum to RSV were performed to compare VRNT and LI-COR. Results: From the bridging study, we showed good concordance between VRNT and LI-COR titers, and similar post-/pre-vaccination titer ratios. From the calibration studies, we can convert VRNT and LI-COR titers into similar IU/ml. Conclusion: The VRNT and LI-COR microneutralization assay correlate well and the titers can be standardized as similar IU/ml, enabling direct comparison of titers from different assays.

Bronchiolitis

Viral bronchiolitis is the most common cause of admission to hospital for infants in high-income countries. Respiratory syncytial virus accounts for 60-80% of bronchiolitis presentations. Bronchiolitis is diagnosed clinically without the need for viral testing. Management recommendations, based predominantly on high-quality evidence, advise clinicians to support hydration and oxygenation only. Evidence suggests no benefit with use of glucocorticoids or bronchodilators, with further evidence required to support use of hypertonic saline in bronchiolitis. Evidence is scarce in the intensive care unit. Evidence suggests use of high-flow therapy in bronchiolitis is limited to rescue therapy after failure of standard subnasal oxygen only in infants who are hypoxic and does not decrease rates of intensive care unit admission or intubation. Despite systematic reviews and international clinical practice guidelines promoting supportive rather than interventional therapy, universal de-implementation of interventional care in bronchiolitis has not occurred and remains a major challenge.

Vaccine Efficacy in Adults in a Respiratory Syncytial Virus Challenge Study

BACKGROUND

Although human respiratory syncytial virus (RSV) is an important cause of illness and death in older adults, no RSV vaccine has been licensed.

METHODS

In a phase 2a study, we randomly assigned healthy adults (18 to 50 years of age), in a 1:1 ratio, to receive a single intramuscular injection of either bivalent prefusion F (RSVpreF) vaccine or placebo. Approximately 28 days after injection, participants were inoculated intranasally with the RSV A Memphis 37b challenge virus and observed for 12 days. The per-protocol prespecified primary end points were the following: reverse-transcriptase-quantitative polymerase-chain-reaction (RT-qPCR)-confirmed detectable RSV infection on at least 2 consecutive days with at least one clinical symptom of any grade from two categories or at least one grade 2 symptom from any category, the total symptom score from day 1 to discharge, and the area under the curve (AUC) for the RSV viral load in nasal-wash samples measured by means of RT-qPCR from day 2 after challenge to discharge. In addition, we assessed immunogenicity and safety.

RESULTS

After participants were inoculated with the challenge virus, vaccine efficacy of 86.7% (95% CI, 53.8 to 96.5) was observed for symptomatic RSV infection confirmed by any detectable viral RNA on at least 2 consecutive days. The median AUC for the RSV viral load (hours × log₁₀ copies per milliliter) as measured by RT-qPCR assay was 0.0 (interquartile range, 0.0 to 19.0) in the vaccine group and 96.7 (interquartile range, 0.0 to 675.3) in the placebo group. The geometric mean factor increase from baseline in RSV A-neutralizing titers 28 days after injection was 20.5 (95% CI, 16.6 to 25.3) in the vaccine group and 1.1 (95% CI, 0.9 to 1.3) in the placebo group. More local injection-site pain was noted in the vaccine group than in the placebo group. No serious adverse events were observed in either group.

CONCLUSIONS

RSVpreF vaccine was effective against symptomatic RSV infection and viral shedding. No evident safety concerns were identified. These findings provide support for further evaluation of RSVpreF vaccine in a phase 3 efficacy study. (Funded by Pfizer; EudraCT number, 2020-003887-21; ClinicalTrials.gov number, NCT04785612.).

Clinical Outcome of Viral Respiratory Tract Infections in Hospitalized Adults in Norway: High Degree of Inflammation and Need of Emergency Care for Cases With Respiratory Syncytial Virus

Background

The clinical features and outcomes of viral respiratory tract infections (RTIs) in adults have not been thoroughly studied, especially the respiratory syncytial virus (RSV) disease burden. It has become apparent that outbreaks of RSV in the elderly are associated with increased hospitalization rates. However, little data exists on the severity of such viral RTIs in adults, particularly the need for hospitalization, respiratory support and intensive care.

Methods

We conducted a retrospective observational single-center study at Østfold Hospital Trust, Norway, during three winter seasons 2015–2018. Patients ≥18 years with either influenza A, influenza B, RSV A/B, human metapneumovirus, parainfluenza virus 1–4 or adenovirus detected in respiratory specimens were included, if they were hospitalized 14 days prior or following the detection date, with signs of RTI. Hospital records on treatment and outcome were investigated, as well as mortality of all causes up to 30 days from discharge.

Results

Of the 1222 infection events that were included, influenza A was the most frequent virus detected (39%), while 179 infection events (14.6%) were due to RSV. Influenza B counted for 24% of the infection events, human metapneumovirus 13%, parainfluenza virus 9% and adenovirus 1%. Patients admitted with RSV more often suffered from COPD and congestive heart failure than patients with influenza A. In addition, RSV patients were overrepresented in the urgent response NEWS score (National Early Warning Score) category ≥5. RSV patients also showed signs of more severe inflammation, with WBC ≥11.1 × 10⁹/L and CRP >100 mg/L, and they were more often treated with antibiotic agents during their hospital stay. However, we found no differences in the need for ICU admission or mortality.

Conclusion

Patients with RSV had more often high values for markers of inflammation and elevated NEWS score when compared to patients hospitalized with other common respiratory viruses. Taken into account that they suffered more frequently from comorbidities like COPD, these patients needed hospitalization more urgently. These findings highlight the need for further investigations on RSV disease in adults and the elderly.

Examining the interseasonal resurgence of respiratory syncytial virus in Western Australia

BACKGROUND

Following a relative absence in winter 2020, a large resurgence of respiratory syncytial virus (RSV) detections occurred during the 2020/2021 summer in Western Australia. This seasonal shift was linked to SARS-CoV-2 public health measures. We examine the epidemiology and RSV testing of respiratory-coded admissions, and compare clinical phenotype of RSV-positive admissions between 2019 and 2020.

METHOD

At a single tertiary paediatric centre, International Classification of Diseases, 10th edition Australian Modification-coded respiratory admissions longer than 12 hours were combined with laboratory data from 1 January 2019 to 31 December 2020. Data were grouped into bronchiolitis, other acute lower respiratory infection (OALRI) and wheeze, to assess RSV testing practices. For RSV-positive admissions, demographics and clinical features were compared between 2019 and 2020.

RESULTS

RSV-positive admissions peaked in early summer 2020, following an absent winter season. Testing was higher in 2020: bronchiolitis, 94.8% vs 89.2% (p=0.01); OALRI, 88.6% vs 82.6% (p=0.02); and wheeze, 62.8% vs 25.5% (p<0.001). The 2020 peak month, December, contributed almost 75% of RSV-positive admissions, 2.5 times the 2019 peak. The median age in 2020 was twice that observed in 2019 (16.4 vs 8.1 months, p<0.001). The proportion of RSV-positive OALRI admissions was greater in 2020 (32.6% vs 24.9%, p=0.01). There were no clinically meaningful differences in length of stay or disease severity.

INTERPRETATION

The 2020 RSV season was in summer, with a larger than expected peak. There was an increase in RSV-positive non-bronchiolitis admissions, consistent with infection in older RSV-naïve children. This resurgence raises concern for regions experiencing longer and more stringent SARS-CoV-2 public health measures.

Evaluation of the Alinity m Resp-4-Plex Assay for the Detection of Severe Acute Respiratory Syndrome Coronavirus 2, Influenza A Virus, Influenza B Virus, and Respiratory Syncytial Virus

The rapid emergence of the coronavirus disease 2019 (COVID-19) pandemic has introduced a new challenge in diagnosing and differentiating respiratory infections. Accurate diagnosis of respiratory infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is complicated by overlapping symptomology, and stepwise approaches to testing for each infection would lead to increased reagent usage and cost, as well as delays in clinical interventions. To avoid these issues, multiplex molecular assays have been developed to differentiate between respiratory viruses in a single test to meet clinical diagnostic needs. To evaluate the analytical performance of the FDA emergency use authorization (EUA)-approved Abbott Alinity m resp-4-plex assay (Alinity m) in testing for SARS-CoV-2, influenza A virus, influenza B virus, and respiratory syncytial virus (RSV), we compared its performance to those of both the EUA-approved Cepheid Xpert Xpress SARS-CoV-2, influenza A/B virus, and RSV assay (Xpert Xpress) and the EUA-approved Roche Cobas SARS-CoV-2 and influenza A/B virus assay (Cobas) in a single-center retrospective analysis. High concordance was observed among all three assays, with kappa statistics showing an almost perfect agreement (>0.90). The limit of detection (LOD) results for SARS-CoV-2 showed the Alinity m exhibiting the lowest LOD at 26 copies/mL, followed by the Cobas at 58 copies/mL and the Xpert Xpress at 83 copies/mL, with LOD results for the influenza A virus, influenza B virus, and RSV viral targets also showing equivalent or better performance on the Alinity m compared to the other two platforms. The Alinity m can be used as a high-volume testing platform for SARS-CoV-2, influenza A virus, influenza B virus, and RSV and exhibits analytical performance comparable to those of both the Xpert Xpress and Cobas assays. IMPORTANCE The rapid emergence of SARS-CoV-2 has introduced a new challenge in diagnosing and differentiating respiratory infections, especially considering the overlapping symptomology of many of these infections and differences in clinical interventions depending on the pathogen identified. To avoid these issues, multiplex molecular assays like the one described in this article need to be developed to differentiate between the most common respiratory pathogens in a single test and most effectively meet clinical diagnostic needs.

Phase 1/2 Randomized Study of the Immunogenicity, Safety and Tolerability of an RSV Prefusion F Vaccine in Adults With Concomitant Inactivated Influenza Vaccine

Background

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in older adults and adults with comorbidities. An effective vaccine is needed. An investigational bivalent prefusion F vaccine (RSVpreF) was assessed in healthy adults.

Methods

This phase 1/2 study randomized adults 18–85 years old to receive placebo or 60, 120, or 240 µg RSVpreF (with or without aluminum hydroxide) alone or concomitantly with seasonal inactivated influenza vaccine (SIIV). Safety and immunogenicity were assessed.

Results

In older adults, reactogenicity events were predominantly mild or moderate among RSVpreF recipients; adverse events through 1 month postvaccination were similar across formulations. Coadministration with SIIV did not appear to affect safety among younger or older adults. All RSVpreF formulations with or without concomitant SIIV elicited robust RSV serum-neutralizing responses in adults aged 50–85 years 1 month postvaccination. Neutralizing titers 1 and 12 months postvaccination were 6.9–14.9 and 2.9–4.5 times, respectively, those before vaccination. SIIV immune responses trended lower when coadministered with RSVpreF.

Conclusions

RSVpreF formulations administered alone or with SIIV were well tolerated and highly immunogenic in older adults, supporting the potential for RSVpreF to protect older adults from RSV disease.

Clinical Trials Registration

NCT03529773.

Respiratory Syncytial Virus

Human respiratory syncytial virus (RSV) is a negative sense single-stranded RNA virus that can result in epidemics of seasonal respiratory infections. Generally, one of the two genotypes (A and B) predominates in a single season and alternate annually with regional variation. RSV is a known cause of disease and death at both extremes of ages in the pediatric and elderly, as well as immunocompromised populations. The clinical impact of RSV on the hospitalized adults has been recently clarified with the expanded use of multiplex molecular assays. Among adults, RSV can produce a wide range of clinical symptoms due to upper respiratory tract infections potentially leading to severe lower respiratory tract infections, as well as exacerbations of underlying cardiac and lung diseases. While supportive care is the mainstay of therapy, there are currently multiple therapeutic and preventative options under development.

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.

Severe acute respiratory syndrome coronavirus 2 and respiratory syncytial virus coinfection in children

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has infected many people around the world. Children are considered an important target group for SARS-CoV-2, as well as other viral infections such as respiratory syncytial virus infection. Both SARS-CoV-2 and respiratory syncytial virus can affect the respiratory tract. Coinfection of SARS-CoV-2 and respiratory syncytial virus can pose significant challenges in terms of diagnosis and treatment in children. This review compares the symptoms, diagnostic methods, and treatment of COVID-19 and respiratory syncytial virus infection in children.

Metabolic Modifications by Common Respiratory Viruses and Their Potential as New Antiviral Targets

Respiratory viruses are known to be the most frequent causative mediators of lung infections in humans, bearing significant impact on the host cell signaling machinery due to their host-dependency for efficient replication. Certain cellular functions are actively induced by respiratory viruses for their own benefit. This includes metabolic pathways such as glycolysis, fatty acid synthesis (FAS) and the tricarboxylic acid (TCA) cycle, among others, which are modified during viral infections. Here, we summarize the current knowledge of metabolic pathway modifications mediated by the acute respiratory viruses respiratory syncytial virus (RSV), rhinovirus (RV), influenza virus (IV), parainfluenza virus (PIV), coronavirus (CoV) and adenovirus (AdV), and highlight potential targets and compounds for therapeutic approaches.

Maternal RSV vaccine development. Where to from here?

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory tract infection and is responsible for a large proportion of infant morbidity and mortality worldwide. Most RSV-related deaths occur in children under six months, and the majority of these occur in low-income settings. To date, there is no known efficacious treatment for RSV infection; hence, prevention remains an important strategy to reduce the global burden of disease. Monoclonal antibodies and vaccinations are currently the two main approaches for prevention of RSV disease. Maternal RSV vaccination is of particular interest as a strategy to protect infants during their most vulnerable period as this approach has proven highly efficacious in other vaccine-preventable conditions such as pertussis and influenza. As results from ongoing phase III clinical trials become available, important decisions will need to be made about the priority and potential implementation of RSV vaccines alongside other public health measures.

Emerging antibody-based products for infectious diseases: Planning for metric ton manufacturing

This review focuses on the emerging monoclonal antibody market for infectious diseases and the metric ton scale manufacturing requirements to meet global demand. Increasing access to existing antibody-based products coupled with the unmet need in infectious disease will likely exceed the current existing global manufacturing capacity. Further, the large numbers of individuals infected during epidemics such as the ongoing COVID-19 pandemic emphasizes the need to plan for metric ton manufacturing of monoclonal antibodies by expanding infrastructure and exploring alternative production systems.

Adjustable Algorithmic Tool for Assessing the Effectiveness of Maternal Respiratory Syncytial Virus (RSV) Vaccination on Infant Mortality in Developing Countries

Acute lower respiratory infection (ALRI) due to RSV is a common cause of global infant mortality, with most cases occurring in developing countries. Using data aggregated from priority countries as designated by the United States Agency for International Development's (USAID) Maternal Child Health and Nutrition (MCHN) program, we created an adjustable algorithmic tool for visualizing the effectiveness of candidate maternal RSV vaccination on infant mortality. Country-specific estimates for disease burden and case fatality rates were computed based on established data. Country-specific RSV-ALRI incidence rates for infants 0-5 months were scaled based on the reported incidence rates for children 0-59 months. Using in-hospital mortality rates and predetermined “inflation factor,” we estimated the mortality of infants aged 0-5 months. Given implementation of a candidate maternal vaccination program, estimated reduction in infant RSV-ALRI incidence and mortality rates were calculated. User input is used to determine the coverage of the program and the efficacy of the vaccine. Using the generated algorithm, the overall reduction in infant mortality varied considerably depending on vaccine efficacy and distribution. Given a potential efficacy of 70% and a maternal distribution rate of 50% in every USAID MCHN priority country, annual RSV-ALRI-related infant mortality is estimated to be reduced by 14,862 cases. The absolute country-specific reduction is dependent on the number of live births; countries with the highest birth rates had the greatest impact on annual mortality reduction. The adjustable algorithm provides a standardized analytical tool in the evaluation of candidate maternal RSV vaccines. Ultimately, it can be used to guide public health initiatives, research funding, and policy implementation concerning the effectiveness of potential maternal RSV vaccination on reducing infant mortality.

Respiratory syncytial virus in severe lower respiratory infections in previously healthy young Ethiopian infants

BACKGROUND

Respiratory Syncytial Virus (RSV) is the commonest cause of acute lower respiratory infections (ALRI) in infants. However, the burden of RSV is unknown in Ethiopia. We aimed to determine the prevalence, seasonality and predictors of RSV infection in young infants with ALRI for the first time in Ethiopia.

METHODS

We performed RSV immuno-chromatographic assay from nasopharyngeal swabs of infants, 29 days to 6 months of age. We included the first 10 eligible infants in each month from June 2018 to May 2019 admitted in a tertiary pediatric center. Clinical, laboratory and imaging data were also collected, and chi-square test and regression were used to assess associated factors with RSV infection.

RESULTS

Among a total of 117 study children, 65% were male and mean age was 3 months. Bronchiolitis was the commonest diagnosis (49%). RSV was isolated from 26 subjects (22.2%) of all ALRI, 37% of bronchiolitis and 11% of pneumonia patients. Although RSV infection occurred year round, highest rate extended from June to November. No clinical or laboratory parameter predicted RSV infection and only rainy season (Adjusted Odds Ratio (AOR) 10.46 [95%. C.I. 1.95, 56.18]) was independent predictor of RSV infection.

CONCLUSIONS

RSV was isolated in a fifth of young infants with severe ALRI, mostly in the rainy season. Diagnosis of RSV infection in our setting require specific tests as no clinical parameter predicted RSV infection. Since RSV caused less than a quarter of ALRI in our setting, the other causes should be looked for in future studies.

Economic-Burden Trajectories in Commercially Insured US Infants With Respiratory Syncytial Virus Infection

BACKGROUND

This study evaluates the long-term respiratory syncytial virus (RSV) burden among preterm and full-term infants in the United States.

METHODS

Infants with birth hospitalization claims and ≥24 months of continuous enrollment were retrospectively identified in the Truven MarketScan Commercial Claims and Encounters database for the period 1 January 2004-30 September 2015. Infants with RSV infection in the first year of life (n = 38 473) were matched to controls (n = 76 825), and remaining imbalances in the number of individuals in each group were adjusted using propensity score methods. All-cause, respiratory-related, and asthma/wheezing-related 5-year average cumulative costs were measured.

RESULTS

Early premature (n = 213), premature (n = 397), late premature (n = 4446), and full-term (n = 33 417) RSV-infected infants were matched to 424, 791, 8875, and 66 735 controls, respectively. After 2 years since RSV diagnosis, all-cause cumulative costs for RSV-infected infants as compared to those for controls increased by $22 081 (95% confidence interval [CI], -$5800-$42 543) for early premature infants, by $14 034 (95% CI, $5095- $22 973) for premature infants, by $10 164 (95% CI, $8835-$11 493) for late premature infants, and by $5404 (95% CI, $5110-$5698) for full-term infants. The 5-year RSV burden increased to $39 490 (95% CI, $18 217-$60 764), $23 160 (95% CI, $13 002-$33 317),$13 755 (95% CI, $12 097-$15 414), and $6631 (95% CI, $6060-$7202), respectively. The RSV burden was higher when stratified by inpatient and outpatient setting and respiratory-related and asthma/wheezing-related costs.

CONCLUSIONS

The RSV burden extends across cost domains and prematurity, with the greatest burden incurred by the second year of follow-up. Findings are useful in determining the cost-effectiveness of RSV therapies in development.

Severe Illnesses Associated With Outbreaks of Respiratory Syncytial Virus and Influenza in Adults

Background

Recent reports have described the contribution of adult respiratory syncytial virus (RSV) infections to the use of advanced healthcare resources and death.

Methods

Data regarding patients aged ≥18 years admitted to any of Maryland’s 50 acute-care hospitals were evaluated over 12 consecutive years (2001–2013). We examined RSV and influenza (flu) surveillance data from the US National Respiratory and Enteric Virus Surveillance System and the Centers for Disease Control and Prevention and used this information to define RSV and flu outbreak periods in the Maryland area. Outbreak periods consisted of consecutive individual weeks during which at least 10% of RSV and/or flu diagnostic tests were positive. We examined relationships of RSV and flu outbreaks to occurrence of 4 advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) due to medically attended acute respiratory illness (MAARI).

Results

Occurrences of all 4 MAARI-related hospital advanced medical outcomes were consistently greater for all adult ages during RSV, flu, and combined RSV–flu outbreak periods compared to nonoutbreak periods and tended to be greatest in adults aged ≥65 years during combined RSV–flu outbreak periods. Rate ratios for all 4 MAARI-related advanced medical outcomes ranged from 1.04 to 1.38 during the RSV, flu, or combined RSV–flu outbreaks compared to the nonoutbreak periods, with all 95% lower confidence limits >1.

Conclusions

Both RSV and flu outbreaks were associated with surges in MAARI-related advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) for adults of all ages.

Club Cell Secreted Protein CC16: Potential Applications in Prognosis and Therapy for Pulmonary Diseases

Club cell secretory protein (CC16) is encoded by the SCGB1A1 gene. It is also known as CC10, secretoglobin, or uteroglobin. CC16 is a 16 kDa homodimeric protein secreted primarily by the non-ciliated bronchial epithelial cells, which can be detected in the airways, circulation, sputum, nasal fluid, and urine. The biological activities of CC16 and its pathways have not been completely understood, but many studies suggest that CC16 has anti-inflammatory and anti-oxidative effects. The human CC16 gene is located on chromosome 11, p12-q13, where several regulatory genes of allergy and inflammation exist. Studies reveal that factors such as gender, age, obesity, renal function, diurnal variation, and exercise regulate CC16 levels in circulation. Current findings indicate CC16 not only may reflect the pathogenesis of pulmonary diseases, but also could serve as a potential biomarker in several lung diseases and a promising treatment for chronic obstructive pulmonary disease (COPD). In this review, we summarize our current understanding of CC16 in pulmonary diseases.

A COVID-19 human viral challenge model. Learning from experience

The controlled human infection model and specifically the human viral challenge model are not dissimilar to standard clinical trials while adding another layer of complexity and safety considerations. The models deliberately infect volunteers, with an infectious challenge agent to determine the effect of the infection and the potential benefits of the experimental interventions. The human viral challenge model studies can shorten the time to assess the efficacy of a new vaccine or treatment by combining this with the assessment of safety. The newly emerging SARS-CoV-2 virus is highly contagious, and an urgent race is on to develop a new vaccine against this virus in a timeframe never attempted before. The use of the human viral challenge model has been proposed to accelerate the development of the vaccine. In the early 2000s, the authors successfully developed a pathogenic human viral challenge model for another virus for which there was no effective treatment and established it to evaluate potential therapies and vaccines against respiratory syncytial virus. Experience gained in the development of that model can help with the development of a COVID-19 HVCM and the authors describe it here.

Safety and Immunogenicity of the Ad26.RSV.preF Investigational Vaccine Coadministered With an Influenza Vaccine in Older Adults

Background

Respiratory syncytial virus (RSV) and influenza cause significant disease burden in older adults. Overlapping RSV and influenza seasonality presents the opportunity to coadminister vaccines for both infections. This study assessed coadministration of the investigational vaccine, Ad26.RSV.preF, an adenovirus serotype 26 (Ad26) vector encoding RSV F protein stabilized in its prefusion conformation (pre-F), with a seasonal influenza vaccine in older adults.

Methods

In this phase 2a, double-blind, placebo-controlled study, 180 adults aged ≥60 years received Ad26.RSV.preF plus Fluarix on day 1 and placebo on day 29, or placebo plus Fluarix on day 1 and Ad26.RSV.preF on day 29 (control).

Results

The coadministration regimen had an acceptable tolerability profile. Reactogenicity was generally higher after Ad26.RSV.preF versus Fluarix, but symptoms were generally transient and mild or moderate. At 28 days after the first vaccination, the upper confidence intervals of the hemagglutination inhibition antibody geometric mean ratio (control/coadministration) for all influenza strains were &lt;2, demonstrating noninferiority. Robust neutralizing and binding antibody responses to RSV A2 were observed in both groups.

Conclusions

Coadministration of Fluarix with Ad26.RSV.preF vaccine had an acceptable safety profile and showed no evidence of interference in immune response. The results are compatible with simultaneous seasonal vaccination with both vaccines.

Clinical Trials Registration

NCT03339713.

Innate Type 2 Responses to Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is a common and contagious virus that results in acute respiratory tract infections in infants. In many cases, the symptoms of RSV remain mild, however, a subset of individuals develop severe RSV-associated bronchiolitis. As such, RSV is the chief cause of infant hospitalization within the United States. Typically, the immune response to RSV is a type 1 response that involves both the innate and adaptive immune systems. However, type 2 cytokines may also be produced as a result of infection of RSV and there is increasing evidence that children who develop severe RSV-associated bronchiolitis are at a greater risk of developing asthma later in life. This review summarizes the contribution of a newly described cell type, group 2 innate lymphoid cells (ILC2), and epithelial-derived alarmin proteins that activate ILC2, including IL-33, IL-25, thymic stromal lymphopoietin (TSLP), and high mobility group box 1 (HMGB1). ILC2 activation leads to the production of type 2 cytokines and the induction of a type 2 response during RSV infection. Intervening in this innate type 2 inflammatory pathway may have therapeutic implications for severe RSV-induced disease.

Metabolic changes during respiratory syncytial virus infection of epithelial cells

Viral infections induce substantial metabolic changes in infected cells to optimize viral production while cells develop countermeasures to restrict that infection. Human respiratory syncytial virus (HRSV) is an infectious pathogen that causes severe lower respiratory tract infections (LRTI) in infants, the elderly, and immunocompromised adults for which no effective treatment or vaccine is currently available. In this study, variations in metabolite levels at different time points post-HRSV infection of epithelial cells were studied by untargeted metabolomics using liquid chromatography/mass spectrometry analysis of methanol cell extracts. Numerous metabolites were significantly upregulated after 18 hours post-infection, including nucleotides, amino acids, amino and nucleotide sugars, and metabolites of the central carbon pathway. In contrast, most lipid classes were downregulated. Additionally, increased levels of oxidized glutathione and polyamines were associated with oxidative stress in infected cells. These results show how HRSV infection influences cell metabolism to produce the energy and building blocks necessary for virus reproduction, suggesting potential therapeutic interventions against this virus.

Impact of Respiratory Syncytial Virus Infection on Host Functions: Implications for Antiviral Strategies

Respiratory syncytial virus (RSV) is one of the leading causes of viral respiratory tract infection in infants, the elderly, and the immunocompromised worldwide, causing more deaths each year than influenza. Years of research into RSV since its discovery over 60 yr ago have elucidated detailed mechanisms of the host-pathogen interface. RSV infection elicits widespread transcriptomic and proteomic changes, which both mediate the host innate and adaptive immune responses to infection, and reflect RSV's ability to circumvent the host stress responses, including stress granule formation, endoplasmic reticulum stress, oxidative stress, and programmed cell death. The combination of these events can severely impact on human lungs, resulting in airway remodeling and pathophysiology. The RSV membrane envelope glycoproteins (fusion F and attachment G), matrix (M) and nonstructural (NS) 1 and 2 proteins play key roles in modulating host cell functions to promote the infectious cycle. This review presents a comprehensive overview of how RSV impacts the host response to infection and how detailed knowledge of the mechanisms thereof can inform the development of new approaches to develop RSV vaccines and therapeutics.

Nanobodies: a new approach for the diagnosis and treatment of viral infectious diseases

With the rise of viral infections and antibiotic resistance, there is a constant need for the development of more sensitive and effective treatment and diagnostic tools. Since their discovery in the early 1990s, Camelidae antibodies have been investigated as potential tools due to their unique structure and favorable characteristics. Members of this family produce conventional IgG antibodies as well as heavy-chain only IgG antibodies that do not possess light chains. The variable domain (VHH), or nanobody, demonstrates unique antigen-binding capabilities, enhanced stability, and its small size allows for delivery into the body using a nebulizer, thereby eliminating the unfavorable use of injections. In addition, the cost-effective and easy in vitro production of these antibodies are an attractive quality in terms of mass production. This review covers the past and current nanobody treatment and diagnostic developments aimed at viral infectious diseases, including a brief overview of protozoal, bacterial, and veterinary viral approaches.

Emerging small and large molecule therapeutics for respiratory syncytial virus

Introduction: Respiratory syncytial virus (RSV) causes lower respiratory tract infections and can lead to morbidity and mortality in the infant, elderly and immunocompromised. There is no vaccine and therapeutic interventions are limited. RSV disease research has yielded the development of several prophylactic and therapeutic treatments. Several promising candidates are currently under investigation.Areas covered: Small and large molecule approaches to RSV treatment were examined and categorized by their mechanism of action using data from PubMed, clinicaltrials.gov, and from the sponsoring organizations publicly available pipeline information. These results are prefaced by an overview of RSV to provide the context for rational therapy development.Expert opinion: While small molecule drugs show promise for RSV treatment, we believe that large molecule therapy using anti-RSV G and F protein monoclonal antibodies (mAbs) will most efficaciously and safely ameliorate RSV disease.

Downregulation of A20 Expression Increases the Immune Response and Apoptosis and Reduces Virus Production in Cells Infected by the Human Respiratory Syncytial Virus

Human respiratory syncytial virus (HRSV) causes severe lower respiratory tract infections in infants, the elderly, and immunocompromised adults. Regulation of the immune response against HRSV is crucial to limiting virus replication and immunopathology. The A20/TNFAIP3 protein is a negative regulator of nuclear factor kappa B (NF-κB) and interferon regulatory factors 3/7 (IRF3/7), which are key transcription factors involved in the inflammatory/antiviral response of epithelial cells to virus infection. Here, we investigated the impact of A20 downregulation or knockout on HRSV growth and the induction of the immune response in those cells. Cellular infections in which the expression of A20 was silenced by siRNAs or eliminated by gene knockout showed increased inflammatory/antiviral response and reduced virus production. Similar results were obtained when the expression of A20-interacting proteins, such as TAX1BP1 and ABIN1, was silenced. Additionally, downregulation of A20, TAX1BP1, and ABIN1 increased cell apoptosis in HRSV-infected cells. These results show that the downregulation of A20 expression might contribute in the control of HRSV infections by potentiating the early innate immune response and increasing apoptosis in infected cells.

Melittin: a venom-derived peptide with promising anti-viral properties

Despite tremendous advances in the development of anti-viral therapeutics, viral infections remain a chief culprit accounting for ongoing morbidity and mortality worldwide. Natural products, in particular animal venoms, embody a veritable cornucopia of exotic constituents, suggesting an immensurable source of anti-infective drugs. In this context, melittin, the principal constituent in the venom of the European honeybee Apis mellifera, has been demonstrated to exert anti-cancer, anti-inflammatory, anti-diabetic, anti-infective, and adjuvant properties. To our knowledge, there is no review appertaining to effects of melittin against viruses, prompting us to synopsize experimental investigations on its anti-viral activity throughout the past decades. Accumulating evidence indicates that melittin curbs infectivity of a diverse array of viruses including coxsackievirus, enterovirus, influenza A viruses, human immunodeficiency virus (HIV), herpes simplex virus (HSV), Junín virus (JV), respiratory syncytial virus (RSV), vesicular stomatitis virus (VSV), and tobacco mosaic virus (TMV). However, medication safety, different routes of administrations, and molecular mechanisms behind the anti-viral activity of melittin should be scrutinized in future studies.

The Respiratory Syncytial Virus Polymerase: A Multitasking Machine

Respiratory syncytial virus (RSV) inflicts a significant toll on human life. An essential element of the virus is its polymerase, a complex capable of transcribing and replicating the viral genome. In an exciting new advance, Gilman et al. resolve the structure of this polymerase, providing valuable mechanistic insight into its activities.