Background EDP-938 is an oral once-daily RSV nucleoprotein (N) inhibitor with potent antiviral activity. In a human RSV challenge trial, EDP-938 significantly reduced viral load and symptom severity. During antiviral development, it is critical to understand the propensity for resistance to develop. In vitro studies of EDP-938 suggest a higher barrier to resistance as compared to RSV fusion inhibitors. We evaluated the development of viral resistance to EDP-938 in a human challenge trial.Methods A subset of the 124 participants with RSV infection were chosen for genetic analysis; 159 nasal wash samples from 48 participants were analyzed using next-generation sequencing of the N gene of RSV. Of the 48 participant sampled, 37 were from EDP-938-treated and 11 were placebo-treated participants, representing 45% and 26% of the participants, respectively. The effects of treatment-emergent mutations on viral load, EDP-938 efficacy, and viral fitness were evaluated.Results Two of the 37 EDP-938-treated participants with samples sequenced had treatment-emergent mutations: N:L139I and N:E112G. From in vitro analysis, N:L139I reduced sensitivity to EDP-938 by approximately 10-fold, while N:E112G had no effect. However, N:L139I was associated with a reduction in viral fitness, suggesting clinical resistance is associated with fitness costs. Neither of these variants were associated with reduced viral clearance.Conclusions In human RSV infections treated with EDP-938, emergence of RSV variants with reduced sensitivity to EDP-938 occurred in only 1 participant and was associated with reduced viral fitness. EDP-938's high barrier to resistance highlights its robust mechanism of action.Clinical Trials Registration NCT03691623. In an RSV human challenge trial only 1 participant had a treatment-emergent mutation associated with resistance to EDP-938. This resistance mutation was associated with reductions in viral fitness. Thus, EDP-938 has a high barrier to resistance.

Background. Respiratory syncytial virus (RSV) infection is a cause of substantial morbidity and mortality in young children. There is currently no effective therapy available. Methods. This was a phase 2 study of the oral RSV fusion protein inhibitor AK0529 in infants aged 1-24 months, hospitalized with RSV infection. In part 1 patients (n=24) were randomized 2:1 to receive a single dose of AK0529 up to 4 mg/kg or placebo. In part 2 patients (n=48) were randomized 2:1 to receive AK0529 at 0.5, 1 or 2 mg/kg bid or placebo for five days. Sparse pharmacokinetic samples were assessed using population pharmacokinetics modelling. Safety, tolerability, viral load, signs and symptoms were assessed daily during treatment. Results. No safety or tolerability signals were detected for AK0529: grade ≥3 treatment-emergent adverse events occurred in 4.1% of patients in AK0529 and 4.2% in placebo groups, respectively, and none led to death or withdrawal from the study. In part 2, targeted drug exposure was reached with 2 mg/kg bid. A numerically greater reduction in median viral load with 2 mg/kg bid AK0529 than with placebo at 96 hours was observed. A -4.0 (95% CI: -4.51, -2.03) median reduction in RSV signs and symptom score from baseline to 96 hours was observed in the 2 mg/kg group, compared with -2.0 (95% CI: -3.42, -1.82) in the placebo group. Conclusions. AK0529 was well tolerated in hospitalized RSV-infected infants. Treatment with AK0529 2 mg/kg bid was observed to reduce viral load and clinical signs and symptoms.

Respiratory syncytial virus (RSV) is the leading, global cause of serious respiratory disease in infants and is an important cause of respiratory illness in older adults. No RSV vaccine is currently available. The RSV fusion (F) glycoprotein is a key antigen for vaccine development, and its prefusion conformation is the target of the most potent neutralizing antibodies. Here, we describe a computational and experimental strategy for designing immunogens that enhance the conformational stability and immunogenicity of RSV prefusion F. We obtained an optimized vaccine antigen after screening nearly 400 engineered F constructs. Through in vitro and in vivo characterization studies, we identified F constructs that are more stable in the prefusion conformation and elicit ~10-fold higher serum-neutralizing titers in cotton rats than DS-Cav1. The stabilizing mutations of the lead construct (847) were introduced onto F glycoprotein backbones of strains representing the dominant circulating genotypes of the two major RSV subgroups, A and B. Immunization of cotton rats with a bivalent vaccine formulation of these antigens conferred complete protection against RSV challenge, with no evidence of disease enhancement. The resulting bivalent RSV prefusion F investigational vaccine has recently been shown to be efficacious against RSV disease in two pivotal phase 3 efficacy trials, one for passive protection of infants by immunization of pregnant women and the second for active protection of older adults by direct immunization.

Background: Monoclonal antibody (palivizumab), intravenous immune globulin (IGIV), or respiratory syncytial virus (RSV)-polyclonal-hyperimmune-globulin (RSV-IG as Respigam (R), RI-001, RI-002) are used with ribavirin in RSV-infected immunocompromised patients, with debated efficacy. Palivizumab-resistance (PR) can arise during treatment of persistent infections in this population. RSV-IG may confer benefit in PR-RSV infection.Methods: RSV-IG [RI-001] was provided for an immunocompromised infant with RSV-pneumonitis refractory to ribavirin and palivizumab. RSV-neutralizing antibody, respiratory RSV load (qPCR), and F-gene-sequence-detection of PR was determined. Prophylactic RSV-IG [RI-002] or palivizumab was administered in a cotton-rat model infected with wild-type and PR-RSV. Lung RSV load and neutralizing antibody were measured.Results: As protective RI-001-neutralizing antibody titers waned in the infant, a subpopulation of PR-escape mutants were detected with a fatal RSV-burden in the lungs. In PR-RSV-infected cotton rats, prophylactic RI-002 reduced RSV-load in the lungs (2.45 vs 0.28 log10 PFU/g lung-tissue reduction, respectively, p < 0.05) and provided protective RSV-neutralizing antibody.Conclusions: RSV-IG and ribavirin use in immunocompromised patients requires further study.

Abstract Background Respiratory syncytial virus (RSV) is a significant cause of severe lower respiratory tract disease in children and older adults, but has no approved vaccine. This study assessed the potential of Ad26.RSV.preF to protect against RSV infection and disease in an RSV human challenge model. Methods In this double-blind, placebo-controlled study, healthy adults aged 18–50 years were randomized 1:1 to receive 1 × 1011 vp Ad26.RSV.preF or placebo intramuscularly. Twenty-eight days postimmunization, volunteers were challenged intranasally with RSV-A (Memphis 37b). Assessments included viral load (VL), RSV infections, clinical symptom score (CSS), safety, and immunogenicity. Results Postchallenge, VL, RSV infections, and disease severity were lower in Ad26.RSV.preF (n = 27) vs placebo (n = 26) recipients: median VL area under the curve (AUC) quantitative real-time polymerase chain reaction: 0.0 vs 236.0 (P = .012; predefined primary endpoint); median VL-AUC quantitative culture: 0.0 vs 109; RSV infections 11 (40.7%) vs 17 (65.4%); median RSV AUC-CSS 35 vs 167, respectively. From baseline to 28 days postimmunization, geometric mean fold increases in RSV A2 neutralizing antibody titers of 5.8 and 0.9 were observed in Ad26.RSV.preF and placebo, respectively. Ad26.RSV.preF was well tolerated. Conclusions Ad26.RSV.preF demonstrated protection from RSV infection through immunization in a human challenge model, and therefore could potentially protect against natural RSV infection and disease. Clinical Trials Registration NCT03334695; CR108398, 2017-003194-33 (EudraCT); VAC18193RSV2002.

Abstract Background Patients with deficiencies of terminal components of complement are at hundreds to thousands fold increased risk of severe and fatal Neisseria spp. infections compared with the general population. Eculizumab is a newly approved monoclonal antibody C5 complement inhibitor. It is indicated for the treatment of atypical hemolytic uremic syndrome (atypical HUS), myasthenia gravis, and paroxysmal nocturnal hemoglobinuria. Because of the complement-depleting effect of Eculizumab dosing (Soliris®, Alexion Pharmaceuticals, Munich, Germany), patients are immunosuppressed for specific infectious pathogens (including Neisseria species) against which protection partially relies on normal complement activity. Because Eculizumab treatment is associated with a dramatically increased risk of Neisseria species. infections, recommendations for Neisseria meningitidis vaccination and antibiotic prophylaxis are contained in Eculizumab prescribing information. However, the most appropriate prevention of infections after Eculizumab has yet to be determined. Methods Case report and literature review. Results A previously healthy 7-year-old male was diagnosed with atypical HUS which included renal failure progressing to dialysis, persistent thrombocytopenia, hemolytic anemia, and hemoglobinuria. Stool cultures and a stool multiplex PCR panel did not detect Shiga-like producing E. coli nor E. coli O157/H7. Eculizumab dosing was therefore planned and Infectious Diseases consultation was obtained for appropriate preventions. The FDA Prescribing Information recommends Neisseria meningitidis vaccination before starting Eculizumab or, if immediate Eculizumab is necessary, to use antibiotic prophylaxis until 2 weeks after vaccination. The accepted protective titer after meningococcal vaccination is population based and uses the serum bactericidal assay (SBA). An antibody titer of >1:4 (human compliment) or 1:8 (rabbit complement) is considered protective. However, this “gold standard” assay incorporates the use of exogenous human or rabbit complement. The protective SBA titers in subjects with terminal complement component deficiencies may not be properly assessed using these same SBA titer protective thresholds. Furthermore, serious meningococcal infections have occurred after appropriate vaccination in patients receiving chronic Eculizumab treatments (ie for paroxysmal nocturnal hemoglobinuria). Finally, SBA protective levels after single Neisseria meningitidis vaccination have not been achieved in majorities of patients with renal failure receiving dialysis and or transplant immunosuppression. Conclusions The current Eculizumab prescribing information recommendations for vaccination and antimicrobial prophylaxis may be inadequate to prevent serious Neisseria infections. Repeated Neisseria meningitidis vaccination and extended antibiotic prophylaxis may afford better protection in patients chronically dosed with Eculizumab.

To determine whether respiratory syncytial virus (RSV) regulates human metabolism, we used positron emission tomography (PET) of patient lungs along with bioenergetics and metabolomics of patient upper airway cells and fluids. We previously found a significant negative monotonic relationship between glucose uptake and respiratory viral infection in 20 pediatric patients (e.g., 70% of infected patients had glucose uptake within 0–3 days). In our recent study, 3 out of 4 patients positive for glucose uptake at later times (>5 days) were positive for RSV infection. At present, the bioenergetics of upper respiratory cells (URCs) from nasal pharyngeal aspirates have not been investigated, and in vitro studies indicate RSV reduces metabolism in cell lines. To define metabolic changes in RSV-infected pediatric patients, we acquired fresh aspirates from 6 pediatric patients. Immediately following aspiration of URCs, we measured the two major energy pathways using an XFe flux analyzer. Glycolysis and mitochondrial respiration were significantly increased in URCs from RSV-infected patients, and mitochondrial respiration was operating at near maximal levels, resulting in loss of cellular capacity to increase respiration with impaired coupling efficiency. Metabolomics analysis of metabolites flushed from the upper airways confirmed a significant increase in TCA cycle intermediates. Taken together, these studies demonstrate RSV induces significant hypermetabolism in pediatric patients’ lungs and respiratory tract. Thus, hypermetabolism is a potential anti-viral drug target and reveals RSV can regulate human metabolism. Contributions to the field Metabolic changes in humans in response to viral infection are largely unknown. In this brief clinical report, we find metabolism is markedly increased in live upper respiratory cells from infants infected with respiratory syncytial virus (RSV) concomitant to changes in metabolites in their upper airway fluids. This sheds light on viral induced hypermetabolism in the airways and offers potential biomarkers for RSV. In addition, this identifies potential therapeutic targets for host directed therapies of aberrant metabolism in RSV. This work has clinical impact as biomarkers and therapeutics for RSV are needed for this pervasive virus that causes infections with long term consequence for some children. Further, advancements in molecular mechanisms underpinning RSV infection biology are constrained by the difficulties in translating model systems to humans as well as relating human studies in adults to infants (Mestas and Hughes, 2004; Papin et al., 2013).

A major challenge in developing improved influenza vaccines is the identification of broadly reactive and protective epitopes. While it is generally believed that the specificity of the antibody response to hemagglutinin (HA) is relatively narrow, we and others have identified individuals that mount a cross-reactive neutralizing antibody response after natural infection. Using plasmablasts from one such individual we generated broadly cross-reactive HA-specific monoclonal antibodies (mAbs). Six of these mAbs bound to the globular head of the HA and one to the stalk region; all provided broad protection against multiple subtypes of influenza A viruses including zoonotic strains in passively immunized mice. Using a peptide ELISA approach, we identified the binding regions of each mAb and subsequently immunized mice with these peptides. Immunized mice showed less weight loss and significantly improved survival against challenges with multiple subtypes as compared with control mice. We next used a similar mapping approach with broadly reactive B cells from mice and ferrets. Based on all of the collected data we generated three different composite HA antigens (HF1, HF2 and HF3) that contained a different mix of broadly reactive epitopes in one native HA structure. Mice immunized with the HFs were protected from multiple challenges, including lethal doses of H1, H3, H5, H6, H7 and H9 viruses. We also showed the HFs protected ferrets from H1, H3, and H9 viruses. Overall, by combining data generated from an examination of B cell and antibody responses following infection and/or vaccination in humans, mice, and ferrets we were able to construct a composite HA that was able to induce broad protection against multiple subtypes of influenza virus.

Background Respiratory syncytial virus (RSV) is the number one cause of lower respiratory tract infections in infants. There are still no vaccines or specific antiviral therapies against RSV, mainly due to the inadequate understanding of RSV pathogenesis. Recent data suggest a role for gut microbiota community structure in determining RSV disease severity. Our objective was to determine the gut microbial profile associated with severe RSV patients, which could be used to help identify at-risk patients and develop therapeutically protective microbial assemblages that may stimulate immuno-protection. Results We enrolled 95 infants from Le Bonheur during the 2014 to 2016 RSV season. Of these, 37 were well-babies and 58 were hospitalized with RSV. Of the RSV infected babies, 53 remained in the pediatric ward (moderate) and 5 were moved to the pediatric intensive care unit at a later date (severe). Stool samples were collected within 72 h of admission; and the composition of gut microbiota was evaluated via 16S sequencing of fecal DNA. There was a significant enrichment in S24_7, Clostridiales, Odoribacteraceae, Lactobacillaceae, and Actinomyces in RSV (moderate and severe) vs. controls. Patients with severe RSV disease had slightly lower alpha diversity (richness and evenness of the bacterial community) of the gut microbiota compared to patients with moderate RSV and healthy controls. Beta diversity (overall microbial composition) was significantly different between all RSV patients (moderate and severe) compared to controls and had significant microbial composition separating all three groups (control, moderate RSV, and severe RSV). Conclusions Collectively, these data demonstrate that a unique gut microbial profile is associated with RSV disease and with severe RSV disease with admission to the pediatric intensive care unit. More mechanistic experiments are needed to determine whether the differences observed in gut microbiota are the cause or consequences of severe RSV disease.

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.

Respiratory syncytial virus (RSV) immunoprophylaxis (IP) has been shown to reduce RSV hospitalization rates in high-risk infants; however, it is unclear whether RSV IP is associated with increased risk of non-RSV disease, particularly non-RSV hospitalizations. We conducted a systematic literature review to understand the occurrences of non-RSV disease and/or non-RSV hospitalizations in published studies of RSV IP. Cochrane, Embase, and PubMed databases were searched and reviewed to summarize data regarding the incidence of RSV and non-RSV respiratory disease among RSV IP recipients and controls in randomized and non-randomized studies. Independent investigators screened and selected studies for inclusion. Risk-of-bias assessment was conducted to assess strength/validity of the data using the Jadad scoring system and Downs and Black quality assessment tool, where appropriate. Twenty studies were included for review (5 randomized controlled trials [RCTs]; 15 non-randomized studies). RCTs of RSV IP demonstrated reductions in RSV hospitalizations and all-cause hospitalizations, with no increase in hospitalizations for non-RSV disease. Non-randomized studies also demonstrated reduced RSV hospitalizations in RSV IP recipients but had mixed results in assessments of hospitalizations for non-RSV disease. When RSV IP recipients and controls were more similar in disease severity risk, results of non-randomized studies aligned more closely with RCTs. Observations of increased non-RSV hospitalization rates among RSV IP recipients in some non-randomized studies could be primarily explained by differences in the clinical characteristics between RSV IP recipients and controls.

Respiratory syncytial virus (RSV) causes severe respiratory disease and infects virtually most children by 2 years of age. It is the leading cause of hospitalization of infants worldwide and remerges later in life to be a serious lower respiratory tract illness in the elderly. Recently, significant emphasis focused on changes in host cellular metabolism in response to viral infection. We performed a retrospective study of pediatric patients infected with RSV and found this infection correlated with increased glucose uptake in the lungs. We characterized cells freshly isolated from naturally RSV infected pediatric patients’ nasopharyngeal aspirates (NPA) and quantified their bioenergetics. Next, we will determine RSV infection induced changes in metabolic responses of different cell types including primary human epithelial cells (NHBE), dendritic cells (DCs), macrophages (MOs) and A549 cell line. Additionally, we will characterize the infect co-cultures of NHBE and DCs/MOs with RSV to determine if their crosstalk can help regulate aberrant NHBE metabolism. We found a dramatic increase in glycolysis and mitochondria respiration in cells isolated from patients’ NPA. RSV infection increases basal respiration, ATP production, and proton leak while reducing mitochondrial oxygen consumption and respiratory capacity in pediatric patients’ NPA. Significant increases in metabolism in the infected patient’s upper respiratory cells ex vivo support our in situ findings in RSV infected patients lungs. Understanding and defining the metabolic changes in the host during RSV infection may lead to novel therapeutic approaches through targeted inhibition of specific cellular metabolic pathways.

Abstract Background PC786 is a nebulized nonnucleoside respiratory syncytial virus (RSV) polymerase inhibitor designed to treat RSV, which replicates in the superficial layer of epithelial cells lining the airways. Methods Fifty-six healthy volunteers inoculated with RSV-A (Memphis 37b) were randomly dosed with either nebulized PC786 (5 mg) or placebo, twice daily for 5 days, from either 12 hours after confirmation of RSV infection or 6 days after virus inoculation. Viral load (VL), disease severity, pharmacokinetics, and safety were assessed until discharge. RSV infection was confirmed by reverse-transcription quantitative polymerase chain reaction with any positive value (intention-to-treat infected [ITT-I] population) or RSV RNA ≥1 log10 plaque-forming unit equivalents (PFUe)/mL (specific intention-to-treat infection [ITT-IS] population) in nasal wash samples. Results In the ITT-I population, the mean VL area under the curve (AUC) was lower in the PC786 group than the placebo group (274.1 vs 406.6 log10 PFUe/mL × hour; P = .0359). PC786 showed a trend toward reduction of symptom score and mucous weight. In ITT-IS (post hoc analysis), the latter was statistically significant as well as VL AUC (P = .0126). PC786 showed an early time to maximum plasma concentration, limited systemic exposure, and long half-life and consequently a 2-fold accumulation over the 5-day dosing period. PC786 was well tolerated. Conclusions Nebulized PC786 demonstrated a significant antiviral effect against RSV, warranting further clinical study. Clinical Trials Registration ClinicalTrials.gov: NCT03382431; EudraCT: 2017-002563-18.

BACKGROUND:Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants, and a need exists for prevention of RSV in healthy infants. Nirsevimab is a monoclonal antibody with an extended half-life that is being developed to protect infants for an entire RSV season with a single intramuscular dose.METHODS:In this trial conducted in both northern and southern hemispheres, we evaluated nirsevimab for the prevention of RSV-associated lower respiratory tract infection in healthy infants who had been born preterm (29 weeks 0 days to 34 weeks 6 days of gestation). We randomly assigned the infants in a 2:1 ratio to receive nirsevimab, at a dose of 50 mg in a single intramuscular injection, or placebo at the start of an RSV season. The primary end point was medically attended RSV-associated lower respiratory tract infection through 150 days after administration of the dose. The secondary efficacy end point was hospitalization for RSV-associated lower respiratory tract infection through 150 days after administration of the dose.RESULTS:From November 2016 through November 2017, a total of 1453 infants were randomly assigned to receive nirsevimab (969 infants) or placebo (484 infants) at the start of the RSV season. The incidence of medically attended RSV-associated lower respiratory tract infection was 70.1% lower (95% confidence interval [CI], 52.3 to 81.2) with nirsevimab prophylaxis than with placebo (2.6% [25 infants] vs. 9.5% [46 infants]; P<0.001) and the incidence of hospitalization for RSV-associated lower respiratory tract infection was 78.4% lower (95% CI, 51.9 to 90.3) with nirsevimab than with placebo (0.8% [8 infants] vs. 4.1% [20 infants]; P<0.001). These differences were consistent throughout the 150-day period after the dose was administered and across geographic locations and RSV subtypes. Adverse events were similar in the two trial groups, with no notable hypersensitivity reactions.CONCLUSIONS:A single injection of nirsevimab resulted in fewer medically attended RSV-associated lower respiratory tract infections and hospitalizations than placebo throughout the RSV season in healthy preterm infants. (Funded by AstraZeneca and Sanofi Pasteur; ClinicalTrials.gov number, NCT02878330.).

Effective treatments for respiratory syncytial virus (RSV) infection are lacking. Here, we report a human proof-of-concept study for RV521, a small-molecule antiviral inhibitor of the RSV-F protein. In this randomized, double-blind, placebo-controlled trial, healthy adults were challenged with RSV-A Memphis-37b. ABSTRACT Effective treatments for respiratory syncytial virus (RSV) infection are lacking. Here, we report a human proof-of-concept study for RV521, a small-molecule antiviral inhibitor of the RSV-F protein. In this randomized, double-blind, placebo-controlled trial, healthy adults were challenged with RSV-A Memphis-37b. After infection was confirmed (or 5 days after challenge virus inoculation), subjects received RV521 (350 mg or 200 mg) or placebo orally every 12 h for 5 days. The primary endpoint was area under the curve (AUC) for viral load, as assessed by reverse transcriptase quantitative PCR (RT-qPCR) of nasal wash samples. The primary efficacy analysis set included subjects successfully infected with RSV who received ≥1 dose of study drug. A total of 66 subjects were enrolled (n = 22 per group); 53 were included in the primary analysis set (RV521 350 mg: n = 16; 200 mg: n = 18; placebo: n = 19). The mean AUC of RT-qPCR-assessed RSV viral load (log10 PFU equivalents [PFUe]/ml · h) was significantly lower with RV521 350 mg (185.26; standard error [SE], 31.17; P = 0.002) and 200 mg (224.35; SE, 37.60; P = 0.007) versus placebo (501.39; SE, 86.57). Disease severity improved with RV521 350 mg and 200 mg versus placebo (P = 0.002 and P = 0.009, respectively, for AUC total symptom score [score × hours]). Daily nasal mucus weight was significantly reduced (P = 0.010 and P = 0.038 for RV521 350 mg and 200 mg, respectively, versus placebo). All treatment-emergent adverse events were grade 1 or 2. No subjects discontinued due to adverse events. There was no evidence of clinically significant viral resistance, and only three variants were detected. RV521 effectively reduced RSV viral load and disease severity in humans and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. NCT03258502.)

Background. Presatovir is an oral respiratory syncytial virus (RSV) fusion inhibitor targeting RSV F protein. In a double-blind, placebo-controlled study in healthy adults experimentally infected with RSV (Memphis-37b), presatovir significantly reduced viral load and clinical disease severity in a dose-dependent manner. Methods. Viral RNA from nasal wash samples was amplified and the F gene sequenced to monitor presatovir resistance. Effects of identified amino acid substitutions on in vitro susceptibility to presatovir, viral fitness, and clinical outcome were assessed. Results. Twenty-eight treatment-emergent F substitutions were identified. Of these, 26 were tested in vitro; 2 were not due to lack of recombinant virus recovery. Ten substitutions did not affect presatovir susceptibility, and 16 substitutions reduced RSV susceptibility to presatovir (2.9- to 410-fold). No substitutions altered RSV susceptibility to palivizumab or ribavirin. Frequency of phenotypically resistant substitutions was higher with regimens containing lower presatovir dose and shorter treatment duration. Participants with phenotypic presatovir resistance had significantly higher nasal viral load area under the curve relative to those without, but substitutions did not significantly affect peak viral load or clinical manifestations of RSV disease. Conclusions. Emergence of presatovir-resistant RSV occurred during therapy but did not significantly affect clinical efficacy in participants with experimental RSV infection.

Most infants are infected with RSV by their second birthday. Despite known risk factors such as prematurity or congenital heart disease, most hospitalized infants are previously healthy. The mechanisms underlying the immunopathology of severe disease is incompletely understood. Our objective was to compare T cell profiles in nasal aspirates between infants with moderate and severe RSV disease hospitalized without immune deficiencies or congenital heart disease, during 2014–2017. Infants requiring intensive care were categorized as having severe disease, while infants maintained in the general ward were categorized as having moderate disease. The T cell profile in nasal aspirates collected 7 days after hospitalization (median 11 days after first symptom onset) was determined by flow cytometry. Nasal aspirates from patients with severe disease were characterized by a higher proportion of CD8+ T cells expressing IL-4 (Tc2) (P=0.024) and a lower proportion of CD8+ T cells expressing IFNγ (Tc1) (P=0.019) compared to patients with moderate disease. Patients with reduced frequencies of Tc1, Tc17, or Th17 cells had shorter durations of hospitalization (P=0.0023, P=0.0188, P=0.0437, respectively). Additionally, patients with severe disease had lower concentrations of IL-17 in nasal aspirates compared to patients with moderate disease (P=0.0133). These results suggest that RSV disease severity is associated with a specific T cell profile, and that Tc2 cells may play an underappreciated role in the development of RSV immunopathology.

Human brain development is rapid during infancy and early childhood. Many disease processes impair this development. Therefore, brain developmental age estimation (BDAE) is essential for all diseases affecting cognitive development. Brain magnetic resonance imaging (MRI) of infants shows brain growth and morphologic patterns during childhood. Therefore, we can estimate the developmental age from brain images. However, MRI analysis is time consuming because each scan contains millions of data points (voxels). We investigated the three-dimensional convolutional neural network (3D CNN), a deep learning algorithm, to rapidly classify neurodevelopmental age with high accuracy based on MRIs. MRIs from normal newborns were obtained from the National Institute of Mental Health (NIMH) Data Archive. Age categories of pediatric MRIs were 3 wks ± 1 wk, 1 yr ± 2 wks, and 3 yrs ± 4 wks. We trained a BDAE method using T1, T2, and proton density (PD) images from MRI scans of 112 individuals using 3D CNN. Compared with the known age, our method has a sensitivity of 99% and specificity of 98.3%. Moreover, our 3D CNN model has better performance in neurodevelopmental age estimation than does 2D CNN.