Management of RSV infections in adult recipients of hematopoietic stem cell transplantation

Case report: Suspected organizing pneumonia secondary to severe respiratory syncytial virus pneumonia in an elderly patient

Respiratory syncytial virus (RSV) usually causes acute respiratory tract infection in infants. In recent years, it has gradually become an important pathogen of lower respiratory tract infection in elderly people with an underlying disease. However, at present, the treatment of severe RSV pneumonia in adults is unclear, and organizing pneumonia (OP) after severe RSV infection has rarely been reported. We reported a 76-year-old man with multiple chronic heart and lung diseases who presented with fever, cough and progressive dyspnea. Finally, severe RSV pneumonia was diagnosed after his nasopharyngeal swabs and bronchoalveolar lavage metagenomic next-generation sequencing tests were positive for RSV. After combined treatment with oral ribavirin, intravenous immunoglobulin and corticosteroids, the patient's condition largely resolved, and he was discharged. However, when the corticosteroids were gradually tapered, the disease relapsed twice, and the patient experienced fever and aggravated dyspnea. Despite the lack of pathological evidence, we highly suspected organizing pneumonia secondary to severe RSV pneumonia based on the typical imaging manifestations and the clinical characteristics of a good response to corticosteroids. Finally, this patient was successfully treated with a course of corticosteroids and followed up for 14 months in total.

Single domain antibodies from camelids in the treatment of microbial infections

Infectious diseases continue to pose significant global health challenges. In addition to the enduring burdens of ailments like malaria and HIV, the emergence of nosocomial outbreaks driven by antibiotic-resistant pathogens underscores the ongoing threats. Furthermore, recent infectious disease crises, exemplified by the Ebola and SARS-CoV-2 outbreaks, have intensified the pursuit of more effective and efficient diagnostic and therapeutic solutions. Among the promising options, antibodies have garnered significant attention due to their favorable structural characteristics and versatile applications. Notably, nanobodies (Nbs), the smallest functional single-domain antibodies of heavy-chain only antibodies produced by camelids, exhibit remarkable capabilities in stable antigen binding. They offer unique advantages such as ease of expression and modification and enhanced stability, as well as improved hydrophilicity compared to conventional antibody fragments (antigen-binding fragments (Fab) or single-chain variable fragments (scFv)) that can aggregate due to their low solubility. Nanobodies directly target antigen epitopes or can be engineered into multivalent Nbs and Nb-fusion proteins, expanding their therapeutic potential. This review is dedicated to charting the progress in Nb research, particularly those derived from camelids, and highlighting their diverse applications in treating infectious diseases, spanning both human and animal contexts.

RSV infection of humanized lung-only mice induces pathological changes resembling severe bronchiolitis and bronchopneumonia

Respiratory syncytial virus (RSV) is a substantial cause of severe lower respiratory tract infections in infants, young children, older adults, and immunocompromised individuals. There is a vital need for effective therapeutics to prevent and/or treat severe RSV infection in these high-risk individuals. The development and pre-clinical testing of candidate RSV therapeutics could be accelerated by their evaluation in animals models that recapitulate bronchiolitis and bronchopneumonia; both hallmark features of severe RSV infection of humans. Previously, we demonstrated that implanted human lung tissue in humanized lung-only mice (LoM) can be infected with RSV resulting in a sustained virus replication. Here, we analyzed RSV-associated human lung pathology in the human lung implants of RSV-infected LoM. RSV infected epithelial cells lining the airway and alveolar regions of human lung implants resulting in hallmark histological features of RSV bronchiolitis and bronchopneumonia including distal airway and alveolar lumens clogged with 1) sloughed and necrotic RSV-infected epithelial cells, 2) neutrophil-containing inflammatory infiltrates, and 3) MUC5B dominated mucus secretions. We also show that treatment of LoM with a small molecule antiviral (ribavirin) or a neutralizing antibody (palivizumab) significantly suppressed and/or prevented RSV infection in vivo. Together, our data show that RSV infection of human lung implants in vivo has appropriate cellular tropism and results in hallmark pathological characteristics of severe bronchiolitis and bronchopneumonia in humans. They also offer proof-of-principle of the utility of this model to evaluate novel approaches for the prevention/treatment of RSV infection.

Clinical characteristics and outcomes of allogeneic hematopoietic stem cell transplantation recipients with coronavirus disease 2019 caused by the Omicron variant: a prospective, observational cohort study

We aimed to describe the clinical characteristics, particularly the occurrence and risk factors of severe/critical illness, in allogeneic hematopoietic stem cell (allo-HSCT) recipients infected with coronavirus disease 2019 (COVID-19) caused by Omicron variant in an observational prospective study (n = 311). The median time from allo-HSCT to COVID-19 diagnosis was 8.5 months (range 0.8-106.1) months. Four patients (1.3%) were reported to be asymptomatic during Omicron variant infection, and 135 (43.4%) patients showed lower respiratory tract disease. Thirty-four (10.9%) patients were categorized into serious infection (severe illness n = 25; critical illness n = 9) and the median duration from COVID-19 diagnosis to serious infections was 6 days (range, 0-29) days. Thirteen (4.2%) and 6 (1.9%) patients required intensive care unit care and invasive mechanical ventilation, respectively. Receiving more than 1 type of immunosuppressive therapies at COVID-19 diagnosis was associated with severity and persistence of infection. Six patients (1.9%) died after diagnosis of COVID-19 infection. The 4-week probability of overall survival after COVID-19 diagnosis was 98.7%, which was 100% and 88.2% for non-serious and serious infection group (P < 0.001), respectively. Thus, we observed a relatively low serious infection and mortality rate in allo-HSCT recipients infected with COVID-19 caused by Omicron variant.

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.

Approach to hematopoietic cell transplant candidates with respiratory viral detection

The management of respiratory viruses prior to hematopoietic cell transplant (HCT) can be controversial and requires special consideration of host factors, transplant parameters, and the specific respiratory virus (RV). In the setting of adenovirus (ADV), human metapneumovirus (HMPV), influenza, parainfluenza virus (PIV), and respiratory syncytial virus (RSV) detection prior to hematopoietic cell transplant (HCT), clinical practice guidelines recommend transplant delay when possible; however, there is much more ambiguity when other respiratory viruses, such as seasonal coronaviruses (CoVs), human rhinovirus (HRV), and SARS-CoV-2, are detected. Our aims for this review include detailing clinical practical guidelines and reviewing current literature on pre-transplant respiratory viral infections (RVIs), including antiviral therapies and prevention strategies, when available. We will center our discussion on three representative clinical scenarios, with the goal of providing practical guidance to clinicians.

Vaccination for Respiratory Syncytial Virus: A Narrative Review and Primer for Clinicians

Respiratory syncytial virus (RSV) poses a significant burden on public health, causing lower respiratory tract infections in infants, young children, older adults, and immunocompromised individuals. Recent development and licensure of effective RSV vaccines provide a promising approach to lessening the associated morbidity and mortality of severe infections. This narrative review aims to empower clinicians with the necessary knowledge to make informed decisions regarding RSV vaccination, focusing on the prevention and control of RSV infections, especially among vulnerable populations. The paper explores the available RSV vaccines and existing evidence regarding their efficacy and safety in diverse populations. Synthesizing this information for clinicians can help the latter understand the benefits and considerations associated with RSV vaccination, contributing to improved patient care and public health outcomes.

American Society of Transplantation and Cellular Therapy Series: #7 - Management of Respiratory Syncytial Virus Infections in Hematopoietic Cell Transplant Recipients

The Practice Guidelines Committee of the American Society of Transplantation and Cellular Therapy (ASTCT) partnered with its Transplant Infectious Disease Special Interest Group (TID-SIG) to update the 2009 compendium-style infectious disease guidelines for hematopoietic cell transplantation (HCT). A new approach was adopted to better serve clinical providers by publishing each standalone topic in the infectious disease series in a concise format of frequently asked questions (FAQ), tables, and figures. Experts in HCT and infectious diseases identified FAQs and then provided answers based on the strength of the recommendation and the level of supporting evidence. In the seventh guideline in the series, we focus on the respiratory syncytial virus (RSV) with FAQs addressing epidemiology, clinical diagnosis, prophylaxis, and treatment. Special consideration was given to RSV in pediatric, cord blood, haploidentical, and T cell-depleted HCT and chimeric antigen receptor T cell therapy recipients, as well as to identify future research directions.

Respiratory syncytial virus in adults with comorbidities: an update on epidemiology, vaccines, and treatments

BACKGROUND

Respiratory syncytial virus (RSV) is widely known as a frequent cause of respiratory distress among adults, particularly in older people. Recent years have witnessed several improvements in respiratory virus detection, leading to more questions about therapeutic management strategies.

OBJECTIVES

This narrative review focuses on the RSV burden in older people and adults with risk factors and provides an update on the main recent developments regarding managing this infection.

SOURCES

A comprehensive PubMed search was conducted till August 2023 to identify studies on RSV among the adult population. We included observational studies, RCTs on vaccines, and different therapies.

CONTENT

This review should give clinicians an overview of RSV epidemiology and burden among older people and adults with pre-existing risk factors, the most recent randomized clinical trials on RSV vaccines, and the existing data on the different therapeutics existing and under development.

IMPLICATIONS

There is a growing body of evidence on RSV burden in adults. The landscape of preventive and curative treatments is quickly evolving.

Respiratory syncytial virus burden and risk factors for severe disease in patients presenting to the emergency department with flu-like symptoms or acute respiratory failure

BACKGROUND

Predictors of Respiratory Syncytial Virus (RSV) infection and determinants of RSV unfavorable outcomes are still unclear. We assessed RSV burden and investigated the risk factors associated with RSV positive swab and RSV severe disease.

METHODS

A retrospective, single center, cohort study included all consecutive patients referred to the emergency department of L. Sacco University Hospital (Milan) with flu-like symptoms or acute respiratory failure (aRF) tested per protocol for SARS-CoV-2, RSV, Influenza A (InvA) during the 2022-2023 autumn/winter season. Clinical characteristics and patients' outcomes were registered. Respiratory failure, need for respiratory support, shock, sepsis or in-hospital death defined severe disease.

MAIN FINDINGS

The analysis included 717 patients (65.1% negative swab, 14.1% InvA, 8.5% RSV, 8.6% SARS-CoV-2, 3.6% other viruses). Compared with the study cohort, RSV patients had the highest occurrence of aRF (62.7%) and severe disease (70.5%); mortality was similar to InvA (6.6% vs 5.9%, p = 0.874). Compared with InvA patients, RSV patients were older (p = 0.009), had higher Charlson index (p = 0.001), higher prevalence of chronic heart failure (p = 0.001) and were more frequently on ICS (p = 0.026) and immunosuppressants (p = 0.018). Heart failure [OR (95%CI):3.286 (1.031-10.835); p = 0.041], chronic exposure to ICS [OR (95%CI):2.377 (1.254-4.505); p = 0.008] and immunosuppressants [OR (95%CI):3.661 (1.246-10.754); p = 0.018] predicted RSV infection. Glycaemia ≥120 mg/dL [OR (95%CI):5.839 (1.155-29.519); p = 0.033], leucocytes ≥8000 cells/μL [OR (95%CI):5.929 (1.090-32.268); p = 0.039], and past/active smoking [OR (95%CI):7.347 (1.301-41.500); p = 0.024] predicted severe RSV disease.

CONCLUSIONS

RSV infection is associated with significant mortality and morbidity. Preventive strategies for RSV infection such as vaccination are highly warranted, especially in older patients with cardiovascular and chronic respiratory conditions.

Ribavirin treatment for respiratory syncytial virus infection in patients with haematologic malignancy and haematopoietic stem cell transplant recipients: a systematic review and meta-analysis

BACKGROUND

Ribavirin use for respiratory syncytial virus (RSV) infection in patients with haematologic malignancies (HM) and haematopoietic stem cell transplant (HSCT) recipients remains controversial.

OBJECTIVES

To summarize the current evidence of ribavirin treatment in association with mortality and progression to lower respiratory tract infection (LRTI) among patients with HM/HSCT with RSV infection.

DATA SOURCES

MEDLINE, Embase, and the Institute for Scientific Information Web of Science.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials and observational studies investigating the effects of ribavirin, compared with treatment without ribavirin, for RSV infection.

PARTICIPANTS

Patients with HM/HSCT.

INTERVENTIONS

Ribavirin versus no ribavirin.

ASSESSMENT OF RISK OF BIAS

The risk of bias in non-randomized studies of exposure (ROBIN-E).

METHODS OF DATA SYNTHESIS

The random-effects model was used to calculate the pooled OR (pOR) with 95% CI for the pooled effect estimates of ribavirin benefits. Grading of recommendation assessment, development, and evaluation was used to evaluate the certainty of evidence.

RESULTS

One randomized controlled trial and 14 observational studies were included, representing 1125 patients with HM/HSCT. Ribavirin use was not associated with lower all-cause or RSV-associated mortality with pORs [95% CI] of 0.81 [0.40, 1.66], I2 = 55% (low certainty of evidence) and 0.48 [0.11, 2.15], I2 = 64% (very low certainty of evidence), respectively. In subgroup analyses, ribavirin use was associated with lower mortality in patients with HM/HSCT with LRTI with pOR [95% CI] of 0.19 [0.07, 0.51], I2 = 0% (moderate certainty of evidence). In subgroup analyses among studies providing adjusted OR, ribavirin use was associated with lower all-cause mortality with pOR of 0.41 [0.23, 0.74], I2 = 0% (moderate certainty of evidence). In addition, aerosolized ribavirin was associated with lower progression to LRTI with pOR [95% CI] of 0.27 [0.09, 0.80], I2 = 71% (low certainty of evidence).

CONCLUSIONS

Ribavirin may be a reasonable option to treat RSV in patients with HM/HSCT in the absence of other effective antiviral agents.

Reshaping Our Knowledge: Advancements in Understanding the Immune Response to Human Respiratory Syncytial Virus

Human respiratory syncytial virus (hRSV) is a significant cause of respiratory tract infections, particularly in young children and older adults. In this review, we aimed to comprehensively summarize what is known about the immune response to hRSV infection. We described the innate and adaptive immune components involved, including the recognition of RSV, the inflammatory response, the role of natural killer (NK) cells, antigen presentation, T cell response, and antibody production. Understanding the complex immune response to hRSV infection is crucial for developing effective interventions against this significant respiratory pathogen. Further investigations into the immune memory generated by hRSV infection and the development of strategies to enhance immune responses may hold promise for the prevention and management of hRSV-associated diseases.

Spatial resolution of virus replication: RSV and cytoplasmic inclusion bodies

Respiratory Syncytial Virus (RSV) is a major cause of respiratory illness in young children, elderly and immunocompromised individuals worldwide representing a severe burden for health systems. The urgent development of vaccines or specific antivirals against RSV is impaired by the lack of knowledge regarding its replication mechanisms. RSV is a negative-sense single-stranded RNA (ssRNA) virus belonging to the Mononegavirales order (MNV) which includes other viruses pathogenic to humans as Rabies (RabV), Ebola (EBOV), or measles (MeV) viruses. Transcription and replication of viral genomes occur within cytoplasmatic virus-induced spherical inclusions, commonly referred as inclusion bodies (IBs). Recently IBs were shown to exhibit properties of membrane-less organelles (MLO) arising by liquid-liquid phase separation (LLPS). Compartmentalization of viral RNA synthesis steps in viral-induced MLO is indeed a common feature of MNV. Strikingly these key compartments still remain mysterious. Most of our current knowledge on IBs relies on the use of fluorescence microscopy. The ability to fluorescently label IBs in cells has been key to uncover their dynamics and nature. The generation of recombinant viruses expressing a fluorescently-labeled viral protein and the immunolabeling or the expression of viral fusion proteins known to be recruited in IBs are some of the tools used to visualize IBs in infected cells. In this chapter, microscope techniques and the most relevant studies that have shed light on RSV IBs fundamental aspects, including biogenesis, organization and dynamics are being discussed and brought to light with the investigations carried out on other MNV.

A randomized controlled trial of presatovir for respiratory syncytial virus after lung transplant

BACKGROUND

Respiratory syncytial virus (RSV) infection in lung transplant recipients is associated with high morbidity. This study evaluated the RSV fusion inhibitor presatovir in RSV-infected lung transplant recipients.

METHODS

In this international Phase 2b, randomized, double-blind, placebo-controlled trial (NCT02534350), adult lung transplant recipients with symptomatic confirmed RSV infection for ≤7 days received oral presatovir 200 mg on day 1 and 100 mg daily on days 2 to 14, or placebo (2:1), with follow-up through day 28. There were 2 coprimary endpoints: time-weighted average change in nasal RSV load from day 1 to 7, calculated from nasal swabs, in the full analysis set ([FAS]; all patients who received study drug and had quantifiable baseline nasal RSV load) and time-weighted average change in nasal RSV load from day 1 to 7 in the subset of patients with pretreatment symptom duration at the median or shorter of the FAS. Secondary endpoints were changes in respiratory infection symptoms assessed using the Influenza Patient-Reported Outcomes questionnaire and lung function measured by spirometry.

RESULTS

Sixty-one patients were randomized, 40 received presatovir, 20 placebo, and 54 were included in efficacy analyses. Presatovir did not significantly improve the primary endpoint in the FAS (treatment difference [95% CI], 0.10 [-0.43, 0.63] log10 copies/ml; p = 0.72) or the shorter symptom-duration subgroup (-0.12 [-0.94, 0.69] log10 copies/ml; p = 0.76). Secondary endpoints were not different between presatovir and placebo groups. Presatovir was generally well tolerated.

CONCLUSIONS

Presatovir treatment did not significantly improve change in nasal RSV load, symptoms, or lung function in lung transplant recipients.

Respiratory Syncytial Virus Infections in Neonates: A Persisting Problem

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections in young infants. It is an enveloped, single-stranded, nonsegmented, negative-strand RNA virus, a member of the family Pneumoviridae. Globally, RSV is responsible for 2.3% of deaths among neonates 0-27 days of age. Respiratory syncytial virus infection is most common in children aged below 24 months. Neonates present with cough and fever. Respiratory syncytial virus-associated wheezing is seen in 20% infants during the first year of life of which 2-3% require hospitalization. Reverse transcriptase polymerase chain reaction (RT-PCR) gives fast results and has higher sensitivity compared with culture and rapid antigen tests and are not affected by passively administered antibody to RSV. Therapy for RSV infection of the LRT is mainly supportive, and preventive measures like good hygiene and isolation are the mainstay of management. Standard precautions, hand hygiene, breastfeeding and contact isolation should be followed for RSV-infected newborns. Recent AAP guidelines do not recommend pavilizumab prophylaxis for preterm infants born at 29-35 weeks without chronic lung disease, hemodynamically significant congenital heart disease and coexisting conditions. RSV can lead to long-term sequelae such as wheezing and asthma, associated with increased healthcare costs and reduced quality of life.

Human T cells efficiently control RSV infection

Respiratory syncytial virus (RSV) infection causes significant morbidity and mortality in infants, immunocompromised individuals, and older individuals. There is an urgent need for effective antivirals and vaccines for high-risk individuals. We used 2 complementary in vivo models to analyze RSV-associated human lung pathology and human immune correlates of protection. RSV infection resulted in widespread human lung epithelial damage, a proinflammatory innate immune response, and elicited a natural adaptive human immune response that conferred protective immunity. We demonstrated a key role for human T cells in controlling RSV infection. Specifically, primed human CD8+ T cells or CD4+ T cells effectively and independently control RSV replication in human lung tissue in the absence of an RSV-specific antibody response. These preclinical data support the development of RSV vaccines, which also elicit effective T cell responses to improve RSV vaccine efficacy.

Recent Advances in Inhaled Nanoformulations of Vaccines and Therapeutics Targeting Respiratory Viral Infections

With the rapid outbreak of respiratory viral infections, various biological (e.g. vaccines, peptides, recombinant proteins, antibodies and genes) and antiviral agents (e.g. ribavirin, palivizumab and valaciclovir) have been successfully developed for the treatment of respiratory virus infections such as influenza, respiratory syncytial virus and SARS-CoV-2 infections. These therapeutics are conventionally delivered via oral, intramuscular or injection route and are associated with several adverse events due to systemic toxicity. The inherent in vivo instability of biological therapeutics may hinder them from being administered without proper formulations. Therefore, we have witnessed a boom in nanotechnology coupled with a needle-free administration approach such as the inhalation route for the delivery of complex therapeutics to treat respiratory infections. This review discussed the recent advances in the inhalation strategies of nanoformulations that target virus respiratory infections.

Prognosis of hospitalized adult patients with respiratory syncytial virus infection: a multicenter retrospective cohort study

OBJECTIVES

Respiratory syncytial virus (RSV) is a common agent of viral respiratory infections with significant morbidity and mortality in adults. The objective of this study is to determine risk factors for mortality, invasive mechanical ventilation and to describe the characteristics of patients who received ribavirin.

METHODS

Retrospective multicenter observational cohort study conducted in Great Paris area hospitals, including patients hospitalized between January 1, 2015 and December 31, 2019 for documented RSV infection. Data were extracted from the AP-HP Health Data Warehouse. The primary endpoint was in-hospital mortality.

RESULTS

1168 patients were hospitalized for RSV infection, including 288 (24.6%) patients who required ICU admission. The median [interquartile range] age of patients was 75 [63-85] years, 54% (n=631/1168) of them were women. In-hospital mortality was 6.6% (n=77/1168) in the whole cohort and 12.8% (n=37/288) in ICU patients. Factors associated with hospital mortality were age>85 years (adjusted odds ratio (aOR)=6.29 95% confidence interval [2.47-15.98]), acute respiratory failure (aOR=2.83 [1.19-6.72]), non-invasive (aOR=12.60 [1.41-112.36]) and invasive mechanical ventilation support (aOR=30.13 [3.17-286.27]) and neutropenia (aOR=13.19 [3.27-53.27]). Factors associated with invasive mechanical ventilation were chronic heart (aOR=1.98 [1.20-3.26]) or respiratory failure (aOR=2.83 [1.67-4.80]), and co-infection (aOR=2.62 [1.60-4.30]). Patients who were treated with ribavirin were significantly younger than others (62 [55-69] vs 75 [63-86] years; p<0.001), more frequently males (n=34/48 (70.8%) vs n=503/1120 (44.9%); p=0.001), and almost exclusively immunocompromised (n=46/48 (95.8%) vs n=299/1120 (26.7%); p<0.001).

CONCLUSIONS

The mortality rate of patients hospitalized with RSV infections was 6.6%. Twenty-five percent of patients required ICU admission.

The Impact of the COVID-19 Pandemic on Respiratory Syncytial Virus Infection: A Narrative Review

Respiratory syncytial virus (RSV) is one of the most common respiratory viruses. It not only affects young children but also the elderly and immunocompromised patients. After the emergence of SARS-CoV-2 and the corona virus disease 2019 (COVID-19) era, a dramatic reduction in RSV activity was found, which coincided with the implementation of public health and social measures (PHSMs). However, the correlation is more complicated than we initially thought. After PHSMs were gradually lifted, a seasonality shift and a delayed RSV outbreak with greater number of infected patients were found in numerous countries, such as Israel, Australia, South Africa, New Zealand, France, United States, and Japan. Several hypotheses and possible reasons explaining the interaction between SARS-CoV-2 and RSV were mentioned. Since RSV vaccinations are still under investigation, administration of palivizumab should be considered in high-risk patients. In the post-COVID-19 era, greater attention should be paid to a further resurgence of RSV. In this narrative review, we conducted a thorough review of the current knowledge on the epidemiology of RSV during the COVID-19 era, the out-of-season outbreak of RSV, and the data on co-infection with RSV and SARS-CoV-2.

Epidemiological and genetic characteristics of respiratory syncytial virus infection in children from Hangzhou after the peak of COVID-19

BACKGROUND

Respiratory syncytial virus (RSV) is one of the main pathogens that causes acute lower respiratory tract infection (ARTI) in infants. During the Coronavirus Disease 2019 (COVID-19) pandemic, although strict interventions have been implemented, RSV infection has not decreased.

OBJECTIVES

To study the epidemiological and genetic characteristics of RSV circulating in Hangzhou after the peak of COVID-19.

METHODS

A total of 1225 nasopharyngeal swabs were collected from outpatients with ARTIs from July 2021 to January 2022 in The Children's Hospital, Zhejiang University School of Medicine.

RESULTS

A total of 267 (21.79%) of the 1225 samples were RSV positive. There was no gender bias. However, an obvious age preference for infection was observed, and children aged 3-6 years were more susceptible, which was very different from previous RSV pandemic seasons. Phylogenetic analysis of 115 sequenced RSV isolates showed that all the RSV-A viruses belong to the ON1 subtype, which could be clustered into three clusters. While all the RSV-B viruses belong to BA9. Further analysis of the mutations highlights the fixation of ten mutations, which should be given extra attention regarding their biological properties.

CONCLUSION

The incidence of RSV infection in preschool children reported in this study is high. Phylogenetic analysis showed that the subtype A ON1 genotype was the dominant strain in Hangzhou from July 2021 to January 2022.

Importance of RNA length for in vitro encapsidation by the nucleoprotein of human Respiratory Syncytial Virus

Respiratory syncytial virus has a negative-sense single-stranded RNA genome constitutively encapsidated by the viral nucleoprotein N, forming a helical nucleocapsid which is the template for viral transcription and replication by the viral polymerase L. Recruitment of L onto the nucleocapsid depends on the viral phosphoprotein P, which is an essential L cofactor. A prerequisite for genome and antigenome encapsidation is the presence of the monomeric, RNA-free, neosynthesized N protein, named N⁰. Stabilization of N⁰ depends on the binding of the N-terminal residues of P to its surface, which prevents N oligomerization. However, the mechanism involved in the transition from N⁰-P to nucleocapsid assembly, and thus in the specificity of viral genome encapsidation, is still unknown. Furthermore, the specific role of N oligomerization and RNA in the morphogenesis of viral factories, where viral transcription and replication occur, have not been elucidated although the interaction between P and N complexed to RNA has been shown to be responsible for this process. Here, using a chimeric protein comprising N and the first 40 N-terminal residues of P, we succeeded in purifying a recombinant N⁰-like protein competent for RNA encapsidation in vitro. Our results showed the importance of RNA length for stable encapsidation and revealed that the nature of the 5′ end of RNA does not explain the specificity of encapsidation. Finally, we showed that RNA encapsidation is crucial for the in vitro reconstitution of pseudo-viral factories. Together, our findings provide insight into respiratory syncytial virus viral genome encapsidation specificity.

Review of respiratory syncytial virus infection among older adults and transplant recipients

Respiratory syncytial virus (RSV) is a common cause of pulmonary infection among children and has been increasingly recognized as an important respiratory pathogen in older adults and immunocompromised hosts. Among older adults, RSV can lead to exacerbations of underlying lung and cardiac disease. It is also associated with significant morbidity and mortality in hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients and may be associated with acute rejection and chronic lung allograft dysfunction among lung transplant recipients (LTRs). Current treatment options for severe RSV disease are limited, and there is a paucity of guidance on RSV treatment among older adults. This narrative review provides a comprehensive overview of RSV disease in older adults, HSCT recipients, and SOT recipients. Nosocomial spread has been reported, thus highlighting the importance of infection prevention and control measures to prevent outbreaks. Antivirals, monoclonal antibodies for immunoprophylaxis, and vaccine development are underway; however, future research is still needed in these critical areas.

Antiviral Therapeutics in Pediatric Transplant Recipients

Recipients of solid organ and hematopoietic stem cell transplantation undergo substantial immune suppression, placing them at risk for opportunistic viral infection. Few randomized controlled trials have been dedicated to the treatment of viral infections in children, and current practices are extrapolated from data generated from adult patients. Here we discuss the prevention and treatment of viral infections using available antiviral drugs, as well as novel agents that may provide benefit to pediatric patients in the future.

Respiratory viral infections in the immunocompromised

PURPOSE OF REVIEW

During much of the COVID-19 pandemic, respiratory viruses other than SARS-CoV-2 did not infect immunocompromised patients. As mitigation strategies lighten, there has been a rapid resurgence of respiratory viruses globally. This review will summarize our current options for the management of the common respiratory viruses in transplant recipients.

RECENT FINDINGS

Expansion of the availability and increased utilization of multiplex molecular assays have allowed the recognition of the scope of respiratory virus infections in the transplant populations. New antivirals for influenza, respiratory syncytial virus (RSV), parainfluenza virus (PIV) and adenovirus show promise to improve outcomes of these important infections.

SUMMARY

Several new antiviral agents, including combination therapy of oseltamivir as well as baloxavir for influenza, fusion and nucleoprotein inhibitors for RSV, DAS181 for PIV and brincidofovir for adenovirus, hold promise to speed clearance of the virus, improve clinical outcomes and reduce the risk of resistance emergence.

Breakthrough therapy designation of nirsevimab for the prevention of lower respiratory tract illness caused by respiratory syncytial virus infections (RSV)

INTRODUCTION

Respiratory syncytial virus (RSV) is a leading cause of serious lower respiratory tract infection (LRTI) in infants and young children. Palivizumab is an RSV-specific prophylactic for use in high-risk infants but treatment requires monthly injections and only modestly reduces hospitalization. Thus, new immunoprophylactic candidates are under development. Nirsevimab (MEDI8897) is a monoclonal antibody with an extended half-life developed to protect infants for an entire RSV season with a single dose.

AREAS COVERED

This review summarizes clinical trial data on nirsevimab. The authors introduce RSV and surface viral proteins involved in infection, then discuss the development and achievements of nirsevimab in clinical trials concluding with expert opinion. Information was compiled from PubMed, clinicaltrials.gov, and press releases from AstraZeneca and Sanofi.

EXPERT OPINION

Nirsevimab (MEDI8897) is an RSV F protein monoclonal antibody and the next-generation RSV medicine having an extended half-life developed for the prevention of LRTI caused by RSV. Nirsevimab will supplant the current standard of care for RSV prevention. Importantly, nirsevimab requires a single dose to last the entire RSV season and may be given to term, preterm, and high-risk infants. However, even with nirsevimab approval there remains a need for an efficacious RSV vaccine and treatments.

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.

Interactions between the Nucleoprotein and the Phosphoprotein of Pneumoviruses: Structural Insight for Rational Design of Antivirals

Pneumoviruses include pathogenic human and animal viruses, the most known and studied being the human respiratory syncytial virus (hRSV) and the metapneumovirus (hMPV), which are the major cause of severe acute respiratory tract illness in young children worldwide, and main pathogens infecting elderly and immune-compromised people. The transcription and replication of these viruses take place in specific cytoplasmic inclusions called inclusion bodies (IBs). These activities depend on viral polymerase L, associated with its cofactor phosphoprotein P, for the recognition of the viral RNA genome encapsidated by the nucleoprotein N, forming the nucleocapsid (NC). The polymerase activities rely on diverse transient protein-protein interactions orchestrated by P playing the hub role. Among these interactions, P interacts with the NC to recruit L to the genome. The P protein also plays the role of chaperone to maintain the neosynthesized N monomeric and RNA-free (called N⁰) before specific encapsidation of the viral genome and antigenome. This review aims at giving an overview of recent structural information obtained for hRSV and hMPV P, N, and more specifically for P-NC and N⁰-P complexes that pave the way for the rational design of new antivirals against those viruses.

Depletion of TAX1BP1 Amplifies Innate Immune Responses during Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the main cause of acute respiratory infections in young children and also has a major impact on the elderly and immunocompromised people. In the absence of a vaccine or efficient treatment, a better understanding of RSV interactions with the host antiviral response during infection is needed. Previous studies revealed that cytoplasmic inclusion bodies (IBs), where viral replication and transcription occur, could play a major role in the control of innate immunity during infection by recruiting cellular proteins involved in the host antiviral response. We recently showed that the morphogenesis of IBs relies on a liquid-liquid-phase separation mechanism depending on the interaction between viral nucleoprotein (N) and phosphoprotein (P). These scaffold proteins are expected to play a central role in the recruitment of cellular proteins to IBs. Here, we performed a yeast two-hybrid screen using RSV N protein as bait and identified the cellular protein TAX1BP1 as a potential partner of this viral protein. This interaction was validated by pulldown and immunoprecipitation assays. We showed that TAX1BP1 suppression has only a limited impact on RSV infection in cell cultures. However, RSV replication is decreased in TAX1BP1-deficient (TAX1BP1 knockout [TAX1BP1KO]) mice, whereas the production of inflammatory and antiviral cytokines is enhanced. In vitro infection of wild-type or TAX1BP1KO alveolar macrophages confirmed that the innate immune response to RSV infection is enhanced in the absence of TAX1BP1. Altogether, our results suggest that RSV could hijack TAX1BP1 to restrain the host immune response during infection. IMPORTANCE Respiratory syncytial virus (RSV), which is the leading cause of lower respiratory tract illness in infants, remains a medical problem in the absence of a vaccine or efficient treatment. This virus is also recognized as a main pathogen in the elderly and immunocompromised people, and the occurrence of coinfections (with other respiratory viruses and bacteria) amplifies the risks of developing respiratory distress. In this context, a better understanding of the pathogenesis associated with viral respiratory infections, which depends on both viral replication and the host immune response, is needed. The present study reveals that the cellular protein TAX1BP1, which interacts with the RSV nucleoprotein N, participates in the control of the innate immune response during RSV infection, suggesting that the N-TAX1BP1 interaction represents a new target for the development of antivirals.

Respiratory Viruses in Solid Organ Transplant Recipients

Solid organ transplantation is often lifesaving, but does carry an increased risk of infection. Respiratory viral infections are one of the most prevalent infections, and are a cause of significant morbidity and mortality, especially among lung transplant recipients. There is also data to suggest an association with acute rejection and chronic lung allograft dysfunction in lung transplant recipients. Respiratory viral infections can appear at any time post-transplant and are usually acquired in the community. All respiratory viral infections share similar clinical manifestations and are all currently diagnosed using nucleic acid testing. Influenza has good treatment options and prevention strategies, although these are hampered by resistance to neuraminidase inhibitors and lower vaccine immunogenicity in the transplant population. Other respiratory viruses, unfortunately, have limited treatments and preventive methods. This review summarizes the epidemiology, clinical manifestations, therapies and preventive measures for clinically significant RNA and DNA respiratory viruses, with the exception of SARS-CoV-2. This area is fast evolving and hopefully the coming decades will bring us new antivirals, immunologic treatments and vaccines.

Evaluation of prognostic scores for respiratory syncytial virus infection in a French multicentre cohort of allogeneic haematopoietic stem cell transplantation recipients

Haematopoietic stem cell transplantation (HSCT) recipients are at risk for severe respiratory syncytial virus (RSV) infection. Two prognostic scores have been proposed to predict the risk of progression from upper respiratory tract infection (URTI) to lower respiratory tract infection (LRTI) and death. This was a multicentre study of allogeneic HSCT recipients diagnosed with an RSV infection between 2010 and 2019 who were retrospectively stratified by the immunodeficiency scoring index (ISI) and the severe immunodeficiency (SID) score. Endpoints were overall survival, RSV-attributable mortality and progression to LRTI after URTI. Prognostic analyses were performed using Cox regression models. We included 147 consecutive patients, including 94 (63.9%) initially diagnosed with URTI and 53 (36.1%) with LRTI. At 90 days, 14 patients had died (survival rate, 90.5%; 95% CI: 85.9-95.3), and nine deaths were attributable to RSV (attributable mortality rate, 5.4%; 95% CI: 2.5-10.0). The cumulative 90-day incidence of LRTI after URTI was 13.8% (95% CI: 7.8-21.6). Neither score showed prognostic value for mortality, while the ISI allowed the prediction of progression to LRTI (p = 0.0008). Our results do not fully replicate the results previously reported in cohorts of HSCT recipients. This may reflect the recent epidemiology of RSV infections in this HSCT cohort.

Successful Treatment of Respiratory Syncytial Virus Infection in an Immunocompromised Patient With Ribavirin

Respiratory syncytial virus (RSV) is a frequent cause of respiratory tract infections in children. Still, it can also cause seasonal outbreaks affecting persons of all ages, especially those with comorbidities or immunocompromised states. Ribavirin is one of the two approved therapies for the treatment of RSV respiratory tract infections. Unfortunately, its aerosolized formulation has been approved only in children, and the oral formulation is not frequently used to treat the infection. However, ribavirin has demonstrated morbidity and mortality benefit in immunocompromised patients. A 70-year-old female had started chemotherapy for a diagnosis of B-cell acute lymphoblastic leukemia (B-ALL). She developed an upper respiratory tract infection (URTI) along with positive RSV status. We started her on oral ribavirin therapy, which had to be stopped after five days of treatment due to an acute hemolytic reaction. She was re-initiated on oral ribavirin after cessation of medication for seven days and showed improvement. Therefore, ribavirin can be used in immunocompromised patients with RSV infection under proper supervision.

Chloroquine and pyrimethamine inhibit the replication of human respiratory syncytial virus A

Human respiratory syncytial virus (hRSV) is a major cause of respiratory illness in young children and can cause severe infections in the elderly or in immunocompromised adults. To date, there is no vaccine to prevent hRSV infections, and disease management is limited to preventive care by palivizumab in infants and supportive care for adults. Intervention with small-molecule antivirals specific for hRSV represents a good alternative, but no such compounds are currently approved. The investigation of existing drugs for new therapeutic purposes (drug repositioning) can be a faster approach to address this issue. In this study, we show that chloroquine and pyrimethamine inhibit the replication of human respiratory syncytial virus A (long strain) and synergistically increase the anti-replicative effect of ribavirin in cellulo. Moreover, chloroquine, but not pyrimethamine, inhibits hRSV replication in the mouse model. Our results show that chloroquine can potentially be an interesting compound for treatment of hRSV infection in monotherapy or in combination with other antivirals.

A Phase 2, Randomized, Double-blind, Placebo-Controlled Trial of Presatovir for the Treatment of Respiratory Syncytial Virus Upper Respiratory Tract Infection in Hematopoietic-Cell Transplant Recipients

Background

Hematopoietic-cell transplant (HCT) recipients are at risk for severe respiratory syncytial virus (RSV) infection. We evaluated the RSV fusion inhibitor presatovir in a randomized, double-blind, Phase II trial in HCT recipients with RSV upper respiratory tract infections.

Methods

Patients were stratified by lymphopenia (<200/µL) and ribavirin use; were randomized, stratified by lymphopenia (<200/μL) and ribavirin use, to receive oral presatovir at 200 mg or a placebo on Days 1, 5, 9, 13, and 17, and were followed through Day 28. The coprimary efficacy endpoints were the time-weighted average change in the nasal RSV viral load between Days 1 and 9 and the proportion of patients developing lower respiratory tract complications (LRTCs) through Day 28.

Results

From 23 January 2015 to 16 June 2017, 189 patients were randomly assigned to treatment (96 to presatovir and 93 to the placebo). Presatovir treatment, compared with the placebo treatment, did not significantly affect (prespecified α = 0.01) a time-weighted average decline in the RSV viral load from Day 1 to 9 (treatment difference, −0.33 log₁₀ copies/mL; 95% confidence interval [CI] −.64 to −.02 log₁₀ copies/mL; P = .040) or the progression to LRTC (11.2% vs 19.5%, respectively; odds ratio, 0.50; 95% CI, .22–1.18; P = .11). In a post hoc analysis among patients with lymphopenia, presatovir decreased LRTC development by Day 28 (2/15 [13.3%] vs 9/14 [64.3%], respectively; P = .008), compared with the placebo. Adverse events were similar for patients receiving presatovir and the placebo.

Conclusions

Presatovir had a favorable safety profile in adult HCT recipients with RSV but did not achieve the coprimary endpoints. Exploratory analyses suggest an antiviral effect among patients with lymphopenia.

Clinical Trials Registration

NCT02254408; EUDRA-CT#2014-002474-36.

Ribavirin shows antiviral activity against SARS-CoV-2 and downregulates the activity of TMPRSS2 and the expression of ACE2 in vitro

Ribavirin is a guanosine analog with broad-spectrum antiviral activity against RNA viruses. Based on this, we aimed to show the anti-SARS-CoV-2 activity of this drug molecule via in vitro, in silico, and molecular techniques. Ribavirin showed antiviral activity in Vero E6 cells following SARS-CoV-2 infection, whereas the drug itself did not show any toxic effect over the concentration range tested. In silico analysis suggested that ribavirin has a broad-spectrum impact on SARS-CoV-2, acting at different viral proteins. According to the detailed molecular techniques, ribavirin was shown to decrease the expression of TMPRSS2 at both mRNA and protein levels 48 h after treatment. The suppressive effect of ribavirin in ACE2 protein expression was shown to be dependent on cell types. Finally, proteolytic activity assays showed that ribavirin also showed an inhibitory effect on the TMPRSS2 enzyme. Based on these results, we hypothesized that ribavirin may inhibit the expression of TMPRSS2 by modulating the formation of inhibitory G-quadruplex structures at the TMPRSS2 promoter. As a conclusion, ribavirin is a potential antiviral drug for the treatment against SARS-CoV-2, and it interferes with the effects of TMPRSS2 and ACE2 expression.

Respiratory viruses

Respiratory viruses are commonly detected in both healthy and immunocompromised children. In most healthy children, respiratory viruses are associated with self-limited upper respiratory tract infections and are not accompanied by significant morbidity. In immunocompromised hosts, including hematopoietic cell transplant recipients, solid organ transplant recipients, and oncology patients, respiratory viruses can be associated with significant clinical manifestations, including prolonged viral shedding, lower respiratory tract disease, the need for supplemental oxygen, late airflow obstruction, and even death. This chapter reviews the major respiratory viruses, including respiratory syncytial virus, human metapneumovirus, influenza, parainfluenza viruses, human rhinoviruses, and human coronaviruses. Other viruses can manifest as pulmonary infection; however, these viruses are discussed elsewhere (see Chapter 17 for discussion of cytomegalovirus and Chapter 22 for discussion of adenoviruses).

A Phase 2b, Randomized, Double-blind, Placebo-Controlled Multicenter Study Evaluating Antiviral Effects, Pharmacokinetics, Safety, and Tolerability of Presatovir in Hematopoietic Cell Transplant Recipients with Respiratory Syncytial Virus Infection of the Lower Respiratory Tract

BACKGROUND

Presatovir significantly reduced nasal viral load, signs, and symptoms of respiratory syncytial virus (RSV) infection in a human challenge study. We evaluated presatovir in hematopoietic-cell transplant (HCT) recipients with RSV lower respiratory tract infection (LRTI).

METHODS

Patients with confirmed RSV in upper and lower respiratory tract and new chest X-ray abnormalities were randomized (1:1), stratified by supplemental oxygen and ribavirin use, to receive oral presatovir 200 mg or placebo every 4 days for 5 doses. The primary endpoint was time-weighted average change in nasal RSV viral load through day 9. Secondary endpoints included supplemental oxygen-free days, incident respiratory failure requiring mechanical ventilation, and all-cause mortality.

RESULTS

From January 31, 2015, to March 20, 2017, 60 patients from 17 centers were randomized (31 presatovir, 29 placebo); 59 received study treatment (50 allogeneic, 9 autologous HCT). In the efficacy population (29 presatovir, 28 placebo), presatovir treatment did not significantly reduce time-weighted average change in viral load (-1.12 vs -1.09 log10 copies/mL; treatment difference -0.02 log10 copies/mL, 95% confidence interval: -.62, .57; P = .94), median supplemental oxygen-free days (26 vs 28 days, P = .84), incident respiratory failure (10.3 vs 10.7%, P = .98), or all-cause mortality (0 vs 7.1%, P = .19) versus placebo. Adverse events were similar between arms (presatovir 80%, placebo 79%). Resistance-associated substitutions in RSV fusion protein emerged in 6/29 presatovir-treated patients.

CONCLUSIONS

Presatovir treatment was well tolerated in HCT patients with RSV LRTI but did not improve virologic or clinical outcomes versus placebo.

CLINICAL TRIALS REGISTRATION

www.clinicaltrials.gov, NCT02254421; EudraCT, #2014-002475-29.

The Need for Antiviral Drugs for Pandemic Coronaviruses From a Global Health Perspective

Respiratory failure due to SARS-CoV-2 has caused widespread mortality, creating an urgent need for effective treatments and a long-term need for antivirals for future emergent coronaviruses. Pharmacotherapy for respiratory viruses has largely been unsuccessful with the exception of early treatment of influenza viruses, which shortens symptom duration and prevents infection in close contacts. Under the rapidly evolving circumstances of the COVID-19 pandemic, most clinical trials of experimental treatments in the United States have focused on later stages of the disease process. Worldwide, the clinical studies of the most impactful drugs, remdesivir and dexamethasone in ACTT-1, RECOVERY, and Solidarity, have studied hospitalized patients. Less than half of clinical trials in the U.S. have investigated oral agents, and the majority have taken place in hospitals at a disease stage where the viral load is already decreasing. The limited success of treatments for respiratory viruses and the viral dynamics of COVID-19 suggest that an antiviral therapy with the greatest impact against pandemic coronaviruses would be orally administered, well-tolerated, target a highly conserved viral protein or host-coronavirus interaction and could be used effectively throughout the world, including resource-poor settings. We examine the treatment of respiratory viral infections and current clinical trials for COVID-19 to provide a framework for effective antiviral therapy and prevention of future emergent coronaviruses and call attention to the need for continued preclinical drug discovery.

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

The Use of Aerosolized Ribavirin in Respiratory Syncytial Virus Lower Respiratory Tract Infections in Adult Immunocompromised Patients: A Systematic Review

Introduction: Respiratory syncytial virus (RSV)-associated lower respiratory tract infection (LRTI) is a concern in immunocompromised patients. Aerosolized ribavirin (RBV AER) is used for treatment of RSV LRTI; however, adverse events and rising drug costs remain a challenge for patient management. The purpose of this systematic review is to summarize the efficacy and adverse event profile of RBV AER for the treatment of hospitalized RSV LRTI in immunocompromised adult patients. Methods: A Medline/PubMed, Embase, Google Scholar, Clinicaltrials.gov, and Cochrane Library database search was conducted from 1966 to January 2019 for the use of RBV AER. Search strategy: [(ribavirin OR ICN1229) AND ("administration, oral" OR "oral" OR "administration, inhalation" OR "inhalation)] AND ("respiratory tract infection" OR "pneumonia"). Studies were reviewed if adult patients were hospitalized, immunocompromised, had RSV LRTI, received RBV AER, and included the outcome of mortality and/or adverse reactions. Methodological quality was assessed using the Cochrane Collaboration GRADE approach. Results: A total of 1787 records were identified and 15 articles met inclusion criteria: hematopoietic stem cell transplant (HSCT)/bone marrow transplant (n = 8), other malignancy/neutropenic (n = 2), solid organ transplant (n = 5). All of the trials are observational with a low quality rating; therefore, a meta-analysis was not performed. The 30-day mortality in studies that contain >10 patients with HSCT, malignancy, and transplant range from 0 to 15.4%, 6.3%, and 0 to 27%, respectively. Improved mortality was cited in 4 studies when RBV AER started before mechanical ventilation or within 2 weeks of symptom onset. Only 3 studies had comparative mortality data with RBV AER and RBV PO. Adverse reactions were reported in 5 studies and included psychiatric manifestations (anxiety, depression, feeling of isolation; n = 14), wheezing/bronchospasm (n = 6), snowflakes/hail blowing in face (n = 6), and precipitation in ventilator tubing (n = 5). Conclusion: There is a lack of high quality, comparative trials on the use of RBV AER for the treatment of RSV LRTI in adult hospitalized immunocompromised patients. There may be a mortality benefit when RBV AER is initiated early after diagnosis or prior to mechanical ventilation, but requires further study. Patient isolation and psychological effects must be weighed against the benefit of therapy.

Pathogen-Specific T Cells Beyond CMV, EBV and Adenovirus

PURPOSE OF REVIEW

Infectious diseases contribute significantly to morbidity and mortality in recipients of allogeneic haematopoietic stem cell transplantation (aHSCT), particularly in the era of highly immunosuppressive transplant regimens and alternate donor transplants. Delayed cellular immune recovery is a major mechanism for the increased risk in these patients. Adoptive cell therapy with ex vivo manipulated pathogen-specific T cells (PSTs) is increasingly taking its place as a treatment strategy using donor-derived or third party-banked cells.

RECENT FINDINGS

The majority of clinical trial data in the form of early-phase studies has been in the prophylaxis or treatment of cytomegalovirus (CMV), Epstein-Barr virus (EBV) and adenovirus (AdV). Advancements in methods to select and enrich PSTs offer the opportunity to target the less common viral pathogens as well as fungi with this technology. Early clinical studies of PSTs targeting polyomaviruses (BK virus and JC virus), human herpesvirus 6 (HHV6), varicella zoster virus (VZV) and Aspergillus spp. have shown promising results in small numbers of patients. Other potential targets include herpes simplex virus (HSV), respiratory viruses and other invasive fungal species. In this review, we describe the burden of disease of this wider spectrum of pathogens, the progress in the development of manufacturing capability, early clinical results and the opportunities and challenges for implementation in the clinic.

Oral Versus Aerosolized Ribavirin for the Treatment of Respiratory Syncytial Virus Infections in Hematopoietic Cell Transplant Recipients

Background

The use of oral ribavirin (RBV) for respiratory syncytial virus (RSV) infections is not well studied. With the drastic increase in the cost of aerosolized RBV, we aimed to compare outcomes of hematopoietic cell transplant (HCT) recipients treated with oral or aerosolized RBV for RSV infections.

Methods

We reviewed the records of 124 HCT recipients with RSV infections treated with oral or aerosolized RBV from September 2014 through April 2017. An immunodeficiency scoring index (ISI) was used to classify patients as low, moderate, or high risk for progression to lower respiratory infection (LRI) or death.

Results

Seventy patients (56%) received aerosolized RBV and 54 (44%) oral RBV. Both groups had a 27% rate of progression to LRI (P = 1.00). Mortality rates did not significantly differ between groups (30-day: aerosolized 10%, oral 9%, P = 1.00; 90-day: aerosolized 23%, oral 11%, P = .10). Classification and regression tree analysis identified ISI ≥7 as an independent predictor of 30-day mortality. For patients with ISI ≥7, 30-day mortality was significantly increased overall, yet remained similar between the aerosolized and oral therapy groups (33% for both). After propensity score adjustment, Cox proportional hazards models showed similar mortality rates between oral and aerosolized therapy groups (30-day: hazard ratio [HR], 1.12 [95% confidence interval {CI}, .345–3.65, P = .845).

Conclusions

HCT recipients with RSV infections had similar outcomes when treated with aerosolized or oral RBV. Oral ribavirin may be an effective alternative to aerosolized RBV, with potential significant cost savings.

High-Dose Intravenous Immunoglobulins in the Treatment of Severe Acute Viral Pneumonia: The Known Mechanisms and Clinical Effects

The current outbreak of viral pneumonia, caused by novel coronavirus SARS-CoV-2, is the focus of worldwide attention. The WHO declared the COVID-19 outbreak a pandemic event on Mar 12, 2020, and the number of confirmed cases is still on the rise worldwide. While most infected individuals only experience mild symptoms or may even be asymptomatic, some patients rapidly progress to severe acute respiratory failure with substantial mortality, making it imperative to develop an efficient treatment for severe SARS-CoV-2 pneumonia alongside supportive care. So far, the optimal treatment strategy for severe COVID-19 remains unknown. Intravenous immunoglobulin (IVIg) is a blood product pooled from healthy donors with high concentrations of immunoglobulin G (IgG) and has been used in patients with autoimmune and inflammatory diseases for more than 30 years. In this review, we aim to highlight the known mechanisms of immunomodulatory effects of high-dose IVIg therapy, the immunopathological hypothesis of viral pneumonia, and the clinical evidence of IVIg therapy in viral pneumonia. We then make cautious therapeutic inferences about high-dose IVIg therapy in treating severe COVID-19. These inferences may provide relevant and useful insights in order to aid treatment for COVID-19.

Population pharmacokinetics of ribavirin in lung transplant recipients and examination of current and alternative dosing regimens

BACKGROUND

Ribavirin is used in the treatment of respiratory paramyxovirus infection in lung transplant recipients; however, its pharmacokinetic profile in the transplant population is unknown despite the potential for alterations due to underlying pathology. Furthermore, the ability of current regimens to meet exposure targets has not been established.

OBJECTIVES

This study examined the pharmacokinetics of ribavirin in a lung transplant population for which current and alternative dosing regimens were assessed.

METHODS

Population pharmacokinetic modelling was conducted in NONMEM using concentration-time data from 24 lung transplant recipients and 6 healthy volunteers. Monte Carlo simulation was used to assess the ability of dosing regimens to achieve pre-specified target concentrations.

RESULTS AND CONCLUSIONS

A three-compartment model with first-order elimination most adequately described ribavirin concentration-time data, with CLCR and patient type (i.e. lung transplant) identified as significant covariates in the model. Simulations indicate that current regimens achieve efficacious concentrations within 24 h of treatment initiation that increase to supra-therapeutic levels over the treatment period. A regimen of 8 mg/kg q6h orally for 48 h followed by 8 mg/kg q24h orally for the remainder of the treatment period was predicted to result in >90% of patients exhibiting concentrations within the defined target range throughout the entire treatment course. Additional work to formally establish target therapeutic concentrations is required; however, this study provides a valuable first step in determining optimal ribavirin treatment regimens for paramyxovirus infections in the lung transplant population.

Community acquired respiratory virus infections in adult patients undergoing umbilical cord blood transplantation

Characteristics and risk factors (RFs) of community-acquired respiratory virus (CARV) infections after umbilical cord blood transplantation (UCBT) are lacking. We retrospectively analyzed CARV infections in 216 single-unit myeloablative UCBT recipients. One-hundred and fourteen episodes of CARV infections were diagnosed in 62 (29%) patients. Upper respiratory tract disease (URTD) occurred in 61 (54%) whereas lower respiratory tract disease (LRTD) in 53 (46%). The 5-year cumulative incidence of CARV infection was 29%. RFs for developing CARV infections were: prednisone-based graft-versus-host disease (GVHD) prophylaxis and grade II–IV acute GVHD. RFs analysis of CARV progression to LRTD identified 2007–2009 period and absolute lymphocyte count (ALC) < 0.5 × 10⁹/L. ALC < 0.5 × 10⁹/L had a negative impact on day 60 mortality in both overall CARV and those with LRTD, whereas proven LRTD was associated with higher day 60 mortality. CARV infections had a negative effect on non-relapse mortality. Overall survival at day 60 after CARV detection was significantly lower in recipients with LRTD compared with URTD (74% vs. 93%, respectively). In conclusion, CARV infections after UCBT are frequent and may have a negative effect in the outcomes, in particular in the context of lymphocytopenia.

Adoptive cell therapies for posttransplant infections

PURPOSE OF REVIEW

Viral and fungal infections cause significant morbidity and mortality following hematopoietic stem-cell transplantation (HSCT), primarily due to the prolonged and complex immunodeficient state that results from conditioning chemo-radiotherapy and subsequent prophylaxis of graft vs. host disease. Although currently available antimicrobial pharmacotherapies have demonstrated short-term efficacy, their toxicities often preclude long-term use, and cessation if frequently associated with recurrent infection. Adoptive cell therapy (ACT) offers the potential to more rapidly reconstitute antimicrobial immune responses in the posttransplant setting.

RECENT FINDINGS

Traditional approaches to manufacture of adoptive T-cell therapies are time consuming and limited to single pathogen specificity. Recent advances in the understanding of immunogenic epitopes, improved methods for pathogen-specific T-cell isolation and cultureware technologies is allowing for rapid generation of ACTs for clinical use.

SUMMARY

The current review summarizes the potential infectious targets and manufacturing methodologies for ACTs and contrasts their clinical efficacy and safety to currently available pharmacotherapies for patients recovering after HSCT.

A Real-World Analysis of Patient Characteristics and Predictors of Hospitalization Among US Medicare Beneficiaries with Respiratory Syncytial Virus Infection

Introduction

Little has been published on respiratory syncytial virus (RSV) among Medicare patients at high risk (HR) of RSV complications due to age or comorbidity.

Methods

Adult patients (at least 18 years of age) with at least 1 diagnostic code for RSV were identified using the 5% US Medicare database from 2011 through 2015. Patients were required to have continuous health plan enrollment for 180 days pre- and 180 days post-RSV diagnosis (baseline and follow-up periods, respectively). HR was defined as diagnosis of chronic lung disease, congestive heart failure, or weakened immune system for 180 days during the baseline period. Patients were categorized as initially hospitalized if hospitalized within 1 day of RSV diagnosis. Logistic regression models were developed to determine predictors of initial hospitalization. Healthcare utilization and costs for 180 days pre- and post-RSV diagnosis were compared.

Results

The study included 756 HR patients who were initially hospitalized with RSV diagnoses. Among these, 61.7% were diagnosed in the emergency department vs 15.3% in a physician’s office, with hypertension (76.3%), chronic obstructive pulmonary disease (COPD) (53.7%), and high cholesterol (52.0%) observed as the most prevalent comorbidities. Of these, COPD, congestive heart failure, chronic kidney disease, and previous evidence of pneumonia were significant predictors of hospitalization. Other significant predictors of hospitalization included older age, hematological malignancies, stroke, and baseline healthcare resource use. Among both HR and non-HR hospitalized patients, there was a significant increase in healthcare resource utilization following hospitalization, including the number of inpatient admissions and longer hospital stays post-RSV diagnosis. The total mean all-cause healthcare costs among HR hospitalized patients increased by $9210 per patient (p < 0.0001) post-RSV diagnosis.

Conclusion

Hospitalized Medicare beneficiaries with RSV infections pose a significant healthcare burden as compared with non-hospitalized patients, mainly driven by higher comorbidity, higher likelihood of multiple inpatient admissions, and costly medical interventions.

Diagnosis of severe respiratory infections in immunocompromised patients

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.