Primary Respiratory Syncytial Virus Infection Research Articles

Association of disease severity and genetic variation during primary Respiratory Syncytial Virus infections

BackgroundRespiratory Syncytial Virus (RSV) disease in young children ranges from mild cold symptoms to severe symptoms that require hospitalization and sometimes result in death. Studies have shown a statistical association between RSV subtype or phylogenic lineage and RSV disease severity, although these results have been inconsistent. Associations between variation within RSV gene coding regions or residues and RSV disease severity has been largely unexplored.MethodsNasal swabs from children (< 8 months-old) infected with RSV in Rochester, NY between 1977–1998 clinically presenting with either mild or severe disease during their first cold-season were used. Whole-genome RSV sequences were obtained using overlapping PCR and next-generation sequencing. Both whole-genome phylogenetic and non-phylogenetic statistical approaches were performed to associate RSV genotype with disease severity.ResultsThe RSVB subtype was statistically associated with disease severity. A significant association between phylogenetic clustering of mild/severe traits and disease severity was also found. GA1 clade sequences were associated with severe disease while GB1 was significantly associated with mild disease. Both G and M2-2 gene variation was significantly associated with disease severity. We identified 16 residues in the G gene and 3 in the M2-2 RSV gene associated with disease severity.ConclusionThese results suggest that phylogenetic lineage and the genetic variability in G or M2-2 genes of RSV may contribute to disease severity in young children undergoing their first infection.

Development and comparison of immunologic assays to detect primary RSV infections in infants.

Effective respiratory syncytial virus (RSV) vaccines have been developed and licensed for elderly adults and pregnant women but not yet for infants and young children. The RSV immune state of the young child, i.e., previously RSV infected or not, is important to the conduct and interpretation of epidemiology studies and vaccine clinical trials. To address the need for sensitive assays to detect immunologic evidence of past infection, we developed, characterized, and evaluated 7 assays including 4 IgG antibody enzyme immunoassays (EIAs), two neutralizing antibody assays, and an IFN-γ EliSpot (EliSpot) assay. The four IgG EIAs used a subgroup A plus subgroup B RSV-infected Hep-2 cell lysate antigen (Lysate), an expressed RSV F protein antigen (F), an expressed subgroup A G protein antigen (Ga), or an expressed subgroup B G protein (Gb) antigen. The two neutralizing antibody assays used either a subgroup A or a subgroup B RSV strain. The EliSpot assay used a sucrose cushion purified combination of subgroup A and subgroup B infected cell lysate. All seven assays had acceptable repeatability, signal against control antigen, lower limit of detection, and, for the antibody assays, effect of red cell lysis, lipemia and anticoagulation of sample on results. In 44 sera collected from children >6 months after an RSV positive illness, the lysate, F, Ga and Gb IgG EIAs, and the subgroup A and B neutralizing antibody assays, and the EliSpot assays were positive in 100%, 100%, 86%, 95%, 43%, and 57%, respectively. The Lysate and F EIAs were most sensitive for detecting RSV antibody in young children with a documented RSV infection. Unexpectedly, the EliSpot assay was positive in 9/15 (60%) of PBMC specimens from infants not exposed to an RSV season, possibly from maternal microchimerism. The Lysate and F EIAs provide good options to reliably detect RSV antibodies in young children for epidemiologic studies and vaccine trials.

Reconstructing the impact of COVID-19 on the immunity gap and transmission of respiratory syncytial virus in Lombardy, Italy

Respiratory syncytial virus (RSV) is a leading cause of hospitalisation and mortality in young children globally. The social distancing measures implemented against COVID-19 in Lombardy (Italy) disrupted the typically seasonal RSV circulation during 2019-2021 and caused substantially more hospitalisations during 2021-2022. The primary aim of this study is to quantify the immunity gap-defined as the increased proportion of the population naïve to RSV infection following the relaxation of COVID-19 restrictions in Lombardy, which has been hypothesised to be a potential cause of the increased RSV burden in 2021-2022. We developed a catalytic model to reconstruct changes in the age-dependent susceptibility profile of the Lombardy population throughout the COVID-19 pandemic. The model is calibrated to routinely collected hospitalisation, syndromic, and virological surveillance data and tested for alternative assumptions on age-dependencies in the risk of RSV infection throughout the pandemic. We estimate that the proportion of the Lombardy population naïve to RSV infection increased by 60.8% (95% CrI: 55.2-65.4%) during the COVID-19 pandemic: from 1.4% (95% CrI: 1.3-1.6%) in 2018-2019 to 2.3% (95% CrI: 2.2-2.5%) before the 2021-2022 season, corresponding to an immunity gap of 0.87% (95% CrI: 0.87-0.88%). We found evidence of heterogeneity in RSV transmission by age, suggesting that the COVID-19 restrictions had variable impact on the contact patterns and risk of RSV infection across ages. We estimate a substantial increase in the population-level susceptibility to RSV in Lombardy during 2019-2021, which contributed to an increase in primary RSV infections in 2021-2022. UK Medical Research Council (MRC), UK Foreign, Commonwealth & Development Office (FCDO), EDCTP2 programme, European Union, Wellcome Trust, Royal Society, EU-MUR PNRR INF-ACT.

Age upon RSV infection and epitope-specificity influence the memory differentiation of antiviral T cells

Abstract Background Despite the high rate of respiratory syncytial virus (RSV) infection and severe symptoms in infants, subsequent infections occur, indicating impaired mucosal immune memory at early life. CD8 T cells are associated with reduced disease in human adult challenge trials and murine models, demonstrating their protective roles. However, since primary RSV infection occurs in infancy, a better understanding of the memory differentiation of RSV-specific respiratory CD8 T cells in neonates is required. Methods CB6F1/J mice were infected at 7, 14, 25 days of life or adulthood to characterize the RSV-specific memory T-cell development. Cells from mediastinal lymph nodes (MLN) and lungs were analyzed by flow cytometry at 7, 11, 14, and 40 days post RSV infection (dpi) after staining with fluorescent antibodies and tetramers specific for M and M2 epitopes in RSV. Results RSV-specific CD8 T cell responses were overall lower in neonates from peak to memory phase, but differ by epitope. At 40dpi, M-specific CD8 T cells preferentially differentiated to central-memory (CM) and resided in the MLN in both adult and neonatal mice, whereas M2-specific CD8 T cells preferentially differentiated to effector-memory (EM) and resided in the lungs in adult but not neonatal mice. Importantly, lung tissue resident memory cell differentiation was limited in early life and increased with age upon infection. Conclusion Our results indicate that the magnitude and memory development of RSV epitope-specific CD8 T cells differ by tissue and age at infection, suggesting that age-associated mucosal immune factors contribute to the development of RSV-specific memory T cells. This work was supported by funding through the NIAID R01AI154619 (A.M.W.M.). Supplemental support provided by USUHS Department of Pediatrics grant PED-86-3658 (A.M.W.M.).

Post-immunobiotics increase resistance to primary respiratory syncytial virus infection and secondary pneumococcal pneumonia.

Previously, we demonstrated that post-immunobiotics derived from Lactobacillus gasseri TMT36, TMT39, and TMT40 strains (HK36, HK39 and HK40, respectively) differentially regulated Toll-like receptor 3 (TLR3)-mediated antiviral respiratory immunity in infant mice. In this work, we investigated whether the HK36, HK39 and HK40 nasal treatments were able to improve the resistance against primary respiratory syncytial virus (RSV) infection and secondary pneumococcal pneumonia. Our results demonstrated that the three treatments increased the resistance to primary viral infection by reducing variations in body weight, RSV titers and lung damage of infected infant mice. Post-immunobiotics significantly enhanced the expressions of interferon (IFN)-λ, IFN-β, IFN-γ, interleukin(IL) - 1β, IL-6, IL-27, Mx1, RNAseL and 2'-5'-oligoadenylate synthetase 1 (OAS1) genes and decreased tumour necrosis factor (TNF)-α in alveolar macrophages of RSV-challenged mice. In addition, the studies in the model of RSV-Streptococcus pneumoniae superinfection showed that the HK39 and HK40 treatments were capable of reducing lung damage, lung bacterial cell counts, and the dissemination of S. pneumoniae into the blood of infant mice. The protective effect was associated with increases in IFN-β, IFN-γ, IL-10, and IL-27 in the respiratory tract. This study demonstrates that the nasal application of the post-immunobiotics HK39 and HK40 stimulates innate respiratory immunity and enhances the defences against primary RSV infection and secondary pneumococcal pneumonia offering an alternative to combat respiratory superinfections in children, which can be fatal.

S3157 Respiratory Syncytial Virus-Associated Hepatitis in Pregnancy

Introduction: Respiratory syncytial virus (RSV) predominantly affects children and typically manifests as an upper respiratory tract infection. Primary RSV infection in immunosuppressed adults may increase risks of disseminated infection manifesting as RSV hepatitis. RSV hepatitis may present with fever, abdominal pain, nausea, vomiting, jaundice, coagulopathy, and elevation of transaminases. Case Description/Methods: A 29-year-old woman with 10 weeks of pregnancy, history of anemia and vitamin B12 deficiency was admitted to the hospital for fatigue, intractable nausea, vomiting and inability to tolerate oral intake. She denied respiratory symptoms. She was taking prenatal multivitamins but denied starting new medications or supplements. At presentation, her vital signs and clinical exam were unremarkable with uterine fundus palpable just above the pubic bone. Initial laboratory work up revealed elevated liver enzymes with AST 497 U/L, ALT 712 U/L, normal total bilirubin and ALP. Abdominal ultrasound (US) demonstrated cholelithiasis without evidence of cholecystitis or common bile duct dilation. Subsequent workup including an acute hepatitis panel; CMV, EBV serology; stool H. pylori testing; and autoimmune workup was negative. HSV IgM serology was indeterminant. A respiratory viral molecular panel by PCR was positive for RSV. Abdominal US with doppler showed normal hepatic and portal vessel blood flow and magnetic resonance cholangiopancreatography was negative for choledocholithiasis. She was treated supportively with intravenous fluids, antiemetics and close fetal monitoring. Her liver enzymes peaked on hospital day 4 with AST 863 U/L, ALT 1214 U/L, total bilirubin 1.1 mg/dL. By hospital day 5, her symptoms improved, and she was discharged. At 5 week follow up, AST and ALT improved to 62 U/L and 82 U/L, respectively. Her elective laparoscopic cholecystectomy was deferred until after delivery due to symptom resolution and absence of acute cholecystitis. Discussion: Disseminated RSV a rare manifestation in immunocompromised individuals. Clinical presentation may be atypical, creating diagnostic challenges. Liver biopsy is rarely required to establish the diagnosis. RSV hepatitis is typically self-limited and can be treated with supportive care as antiviral agents have no proven efficacy. A high index of suspicion is required for early identification of RSV hepatitis as timely supportive care may prevent progression to acute liver failure. Table 1. - Laboratory Testing Done to Investigate Emesis Etiology Caption Laboratory Test Reference Range and Units Results Liver Function Tests Alanine aminotransferase (ALT) 0-34 U/L 990 (H) Aspartate aminotransferase (AST) 15-46 U/L 750 (H) Alkaline phosphatase (ALP) 38-126 U/L 89 (N) Total bilirubin 0.2-1.3 mg/dL 1.4 (H) Total Protein 6.3-8.2 g/dL 6.4 (N) Albumin 3.5-5.0 g/dL 3.6 (N) Coagulation Studies Prothrombin time (PT) 9.0-12.0 10.9 (N) International normalized ratio (INR) 0.9-1.1 1.0 (N) Viral Serologies Hepatitis A, IgM Non-reactive Non-reactive Hepatitis B, core IgM Non-reactive Non-reactive Hepatitis B, surface antigen Non-reactive Non-reactive Hepatitis C antibody Non-reactive Non-reactive Hepatitis E antibody Non-reactive Non-reactive Human immunodeficiency virus 1 and 2 antibody/antigen Non-reactive Non-reactive Herpes simplex virus 1 and 2 IgM < =0.89 0.96 (intermediate) Cytomegalovirus quantitative PCR Non-reactive Not detected Epstein Barr virus, IgM Not detected Not detected Influenza A, antigen Not detected Not detected Influenza B, antigen Not detected Not detected Respiratory Syncytial Virus Not detected Detected Autoimmune liver disease panel Liver-Kidney Microsome-1 Antibody IgG (Anti-LMK) 0.0 - 24.9 U 0.8 (N) Antinuclear antibody (ANA) titer < 1:80 < 1:80 (N) Anti-smooth muscle antibody (ASMA) 0-19 Units 6 (N) Antimitochondrial antibody (AMA) 0.0-24.9 Units 2.4 (N) Miscellaneous Rapid plasma regain (RPR) Negative Negative Total Creatinine Kinase (CK) 30-170 U/L < 20 (L) H. pylori antigen Negative Negative - H: High; N: Normal; L: Low.

Age-specific hospitalization risk of primary and secondary respiratory syncytial virus infection among young children

ObjectivesElucidating the infection dynamics that lead to severe respiratory syncytial virus (RSV) pneumonia and hospitalization among young children are critical. We explored the role of infection parity as well as age in months for RSV-associated hospitalization among young children in Japan. MethodsWe used a sequential transmission catalytic model to capture the transmission mechanisms of RSV among infants in an endemic state. We investigated data on the age-dependent seroprevalence and incidence rate of hospitalization in Japan, and jointly estimated the age-specific risk of hospitalization during primary RSV infection and relative risk of hospitalization during secondary infection in children aged <5 years. ResultsThe estimated risk of hospitalization with primary infection was 0.08 (95% CI: 0.05-0.14) in infants aged 0-2 months. The estimated relative risk of hospitalization owing to secondary infection was 0.18 (95% CI: 0.01-2.04). ConclusionOur simple models successfully captured the infection dynamics of RSV among young children in Japan. The age group of early infancy may be most vulnerable to infection and hospitalization, offering key insights into future vaccinations. The burden of hospitalization from secondary infection may be less important in young children.

Respiratory syncytial virus, recurrent wheeze and asthma: A narrative review of pathophysiology, prevention and future directions.

Globally, respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in young children, and the association between severe RSV disease and later recurrent wheeze and asthma is well established. Whilst a causal link between RSV and wheeze/asthma is not yet proven, immunological evidence suggests skewing towards a Th2-type response, and dampening of IFN-γ antiviral immunity during RSV infection underpins airway hyper-reactivity in a subset of susceptible children after RSV infection. Age at primary RSV infection, viral co-infection and genetic influences may act as effect-modifiers. Despite the significant morbidity and mortality burden of RSV disease in children, there is currently no licensed vaccine. Recent advancements in RSV preventatives, including long-acting monoclonal antibodies and maternal vaccinations, show significant promise and we are on the cusp of a new era in RSV prevention. However, the potential impact of RSV preventatives on subsequent wheeze and asthma remains unclear. The ongoing COVID-19 pandemic and associated public health measures have disrupted the usual seasonality of RSV. Whilst this has posed challenges for health-care services it has also enhanced our understanding of RSV transmission. The near absence of RSV cases during the first year of the pandemic in the context of strict public health measures has provided a rare opportunity to study the impact of delayed age of primary RSV infection on asthma prevalence. In this review, we summarise current understanding of the association between RSV, recurrent wheeze and asthma with a focus on pathophysiology, preventative strategies and future research priorities.

Mucosal immunization with an adenoviral vector vaccine confers superior protection against RSV compared to natural immunity.

Respiratory syncytial virus (RSV) infections are the leading cause of severe respiratory illness in early infancy. Although the majority of children and adults mount immune responses against RSV, recurrent infections are frequent throughout life. Humoral and cellular responses contribute to an effective immunity but also their localization at respiratory mucosae is increasingly recognized as an important factor. In the present study, we evaluate a mucosal vaccine based on an adenoviral vector encoding for the RSV fusion protein (Ad-F), and we investigate two genetic adjuvant candidates that encode for Interleukin (IL)-1β and IFN-β promoter stimulator I (IPS-1), respectively. While vaccination with Ad-F alone was immunogenic, the inclusion of Ad-IL-1β increased F-specific mucosal immunoglobulin A (IgA) and tissue-resident memory T cells (TRM). Consequently, immunization with Ad-F led to some control of virus replication upon RSV infection, but Ad-F+Ad-IL-1β was the most effective vaccine strategy in limiting viral load and weight loss. Subsequently, we compared the Ad-F+Ad-IL-1β-induced immunity with that provoked by a primary RSV infection. Systemic F-specific antibody responses were higher in immunized than in previously infected mice. However, the primary infection provoked glycoprotein G-specific antibodies as well eventually leading to similar neutralization titers in both groups. In contrast, mucosal antibody levels were low after infection, whereas mucosal immunization raised robust F-specific responses including IgA. Similarly, vaccination generated F-specific TRM more efficiently compared to a primary RSV infection. Although the primary infection resulted in matrix protein 2 (M2)-specific T cells as well, they did not reach levels of F-specific immunity in the vaccinated group. Moreover, the infection-induced T cell response was less biased towards TRM compared to vaccine-induced immunity. Finally, our vaccine candidate provided superior protection against RSV infection compared to a primary infection as indicated by reduced weight loss, virus replication, and tissue damage. In conclusion, our mucosal vaccine candidate Ad-F+Ad-IL-1β elicits stronger mucosal immune responses and a more effective protection against RSV infection than natural immunity generated by a previous infection. Harnessing mucosal immune responses by next-generation vaccines is therefore a promising option to establish effective RSV immunity and thereby tackle a major cause of infant hospitalization.

Type I interferons and MAVS signaling are necessary for tissue resident memory CD8+ T cell responses to RSV infection.

Respiratory syncytial virus (RSV) can cause bronchiolitis and viral pneumonia in young children and the elderly. Lack of vaccines and recurrence of RSV infection indicate the difficulty in eliciting protective memory immune responses. Tissue resident memory T cells (TRM) can confer protection from pathogen re-infection and, in human experimental RSV infection, the presence of lung CD8+ TRM cells correlates with a better outcome. However, the requirements for generating and maintaining lung TRM cells during RSV infection are not fully understood. Here, we use mouse models to assess the impact of innate immune response determinants in the generation and subsequent expansion of the TRM cell pool during RSV infection. We show that CD8+ TRM cells expand independently from systemic CD8+ T cells after RSV re-infection. Re-infected MAVS and MyD88/TRIF deficient mice, lacking key components involved in innate immune recognition of RSV and induction of type I interferons (IFN-α/β), display impaired expansion of CD8+ TRM cells and reduction in antigen specific production of granzyme B and IFN-γ. IFN-α treatment of MAVS deficient mice during primary RSV infection restored TRM cell expansion upon re-challenge but failed to recover TRM cell functionality. Our data reveal how innate immunity, including the axis controlling type I IFN induction, instructs and regulates CD8+ TRM cell responses to RSV infection, suggesting possible mechanisms for therapeutic intervention.

Protective antigenic sites identified in respiratory syncytial virus fusion protein reveals importance of p27 domain

Respiratory syncytial virus (RSV) vaccines primarily focused on surface fusion (F) protein are under development. Therefore, to identify RSV‐F protective epitopes, we evaluated 14 antigenic sites recognized following primary human RSV infection. BALB/c mice were vaccinated with F peptides, F proteins, or RSV‐A2, followed by rA2‐Line19F challenge. F peptides generated binding antibodies with minimal in vitro neutralization titers. However, several F peptides (including Site II) reduced lung viral loads and lung pathology scores in animals, suggesting partial protection from RSV disease. Interestingly, animals vaccinated with peptides (aa 101–121 and 110–136) spanning the F‐p27 sequence, which is only present in unprocessed F0 protein, showed control of viral loads with significantly reduced pathology compared with mock‐vaccinated controls. Furthermore, we observed F‐p27 expression on the surface of RSV‐infected cells as well as lungs from RSV‐infected mice. The anti‐p27 antibodies demonstrated antibody‐dependent cellular cytotoxicity (ADCC) of RSV‐infected A549 cells. These findings suggest that p27‐mediated immune response may play a role in control of RSV disease in vivo, and F‐p27 should be considered for inclusion in an effective RSV vaccine.

Presence of maternal antibody at initial respiratory syncytial virus (RSV) infection shapes innate and adaptive responses following repeat RSV exposure

Abstract RSV is the leading cause of childhood hospitalization due to bronchiolitis and a significant risk factor for the development of allergic airway responses. Maternal vaccination has emerged as a promising strategy to protect infants against severe disease. However, the presence of maternal antibody (matAb) at primary RSV infection has been linked to development of wheeze later in life. Therefore, we sought to understand how high levels of matAb during early life RSV infection shapes innate and adaptive immune responses on repeat RSV exposure. Using a murine model of maternal vaccination, we assessed immune responses following adult RSV re-challenge of infants born to unvaccinated and RSV preF-vaccinated dams. Presence of matAb at primary RSV infection resulted in differential activation of resident lung populations at 4 days post-secondary infection (DPSI). Specifically, proliferation of IL-5+ and IL-13+ type 2 innate lymphoid cells were increased in association with elevated numbers of eosinophils in the alveolar space. At 8 DPSI, IL-4-, IL-5-, and IL-13-producing, but not IFNγ-producing, CD4+ T cells were significantly increased, indicating a dominant Th2 response in mice born to vaccinated dams. Importantly, lung inflammation and mucus production were similarly elevated in mice born to immunized and unimmunized dams, suggesting that maternal vaccination did not prevent pathology on repeat infection. Taken together, these data demonstrate that the presence of matAb at primary RSV infection differentially alters innate and adaptive immune responses on secondary RSV exposure. Understanding the mechanisms that drive differential cell activation in the presence of matAb will guide future maternal immunization strategies.

Airway gene-expression classifiers for respiratory syncytial virus (RSV) disease severity in infants

BackgroundA substantial number of infants infected with RSV develop severe symptoms requiring hospitalization. We currently lack accurate biomarkers that are associated with severe illness.MethodWe defined airway gene expression profiles based on RNA sequencing from nasal brush samples from 106 full-tem previously healthy RSV infected subjects during acute infection (day 1–10 of illness) and convalescence stage (day 28 of illness). All subjects were assigned a clinical illness severity score (GRSS). Using AIC-based model selection, we built a sparse linear correlate of GRSS based on 41 genes (NGSS1). We also built an alternate model based upon 13 genes associated with severe infection acutely but displaying stable expression over time (NGSS2).ResultsNGSS1 is strongly correlated with the disease severity, demonstrating a naïve correlation (ρ) of ρ = 0.935 and cross-validated correlation of 0.813. As a binary classifier (mild versus severe), NGSS1 correctly classifies disease severity in 89.6% of the subjects following cross-validation. NGSS2 has slightly less, but comparable, accuracy with a cross-validated correlation of 0.741 and classification accuracy of 84.0%.ConclusionAirway gene expression patterns, obtained following a minimally-invasive procedure, have potential utility for development of clinically useful biomarkers that correlate with disease severity in primary RSV infection.

Respiratory syncytial virus in young children: community cohort study integrating serological surveys, questionnaire and electronic health records, Born in Bradford cohort, England, 2008 to 2013.

BackgroundBronchiolitis caused by respiratory syncytial virus (RSV) is a major cause of mortality and morbidity in infants.AimTo describe RSV epidemiology in children in the community in a high-income setting.MethodsWe used stored blood samples from the United Kingdom Born in Bradford cohort study that had been collected at birth, age 1 and 2 years old, tested for IgG RSV postfusion F antibody and linked to questionnaires and primary and hospital care records. We used finite mixture models to classify children as RSV infected/not infected according to their antibody concentrations at age 1 and 2 years. We assessed risk factors for primary RSV infection at each age using Poisson regression models.ResultsThe study cohort included 700 children with cord blood samples; 490 had additional blood samples taken at both ages 1 and 2 years old. Of these 490 children, 258 (53%; 95% confidence interval (CI): 48–57%) were first infected with RSV at age 1, 99 of whom (38%; 95% CI: 33–43%) had been in contact with healthcare during peak RSV season (November–January). Having older siblings, birth in October–June and attending formal childcare were associated with risk of RSV infection in infancy. By age 2, a further 164 of 490 children (33%; 95% CI: 29–38%) had been infected.ConclusionOver half of children experienced RSV infection in infancy, a further one third had evidence of primary RSV infection by age 2, and one in seven remained seronegative by their second birthday. These findings will inform future analyses to assess the cost-effectiveness of RSV vaccination programmes in high-income settings.

133. validation of a Global Respiratory Severity Score in Infants with Primary RSV Infection

BackgroundWe recently developed a global respiratory severity score (GRSS) as a research tool from (n=139) infants with primary respiratory syncytial virus (RSV) infection enrolled prospectively in the Assessing Predictors of Infant RSV Effects and Severity (AsPIRES) study. The objective of the present study was to validate our original findings that the GRSS correlates well with clinical outcomes including hospitalization and length of stay (LOS) utilizing an independent cohort.MethodsClinical and demographic data on infants with primary RSV infection were abstracted from the electronic medical record. The GRSS was calculated by applying the original training data formula to the new data set. We compared the mean GRSS between the hospitalized and non-hospitalized group with Welch two sample t-test, and correlated it with hospitalization and LOS using Pearson’s correlation test.ResultsA total of 184 (98 hospitalized and 86 non-hospitalized) subjects were enrolled. The hospitalized and non-hospitalized infants were different in general appearance, the percentage with rales, retractions, lethargy, respiratory rate and oxygen saturation. The hospitalized group had a significantly (t=9.334, p< 0.0001) higher GRSS (4.20±2.10) than the non-hospitalized group (1.76±1.41). Using GRSS ≤3.5 as the classification criterion, we correctly predicted the hospitalization status of 131 (71.2%) subjects. The area under the ROC curve of the GRSS as a classifier of hospitalization is AUC=0.8265 (p< 0.0001). Pearson correlation between the GRSS and LOS is (p< 0.0001).Area under the ROC curve of the GRSS Boxplot demonstrating the difference in GRSS between hospitalized and non hospitalized infants ConclusionInfants hospitalized with RSV have a significantly higher GRSS than non-hospitalized subjects, and the GRSS is strongly associated with LOS. GRSS can also serve as an acceptable predictor of hospitalization. We are currently re-training the GRSS model with both datasets and believe it will lead to an improved predictive power of hospitalization.Disclosures All Authors: No reported disclosures

MAVS Deficiency Is Associated With a Reduced T Cell Response Upon Secondary RSV Infection in Mice.

Infections with respiratory syncytial virus (RSV) occurs repeatedly throughout life because sustained, protective memory responses fail to develop. Why this occurs is not known. During RSV infection the recognition of the virus via the cytosolic RIG-I like receptors and signaling via the adaptor protein MAVS is crucial for mounting an innate immune response. However, if this signaling pathway is important for T cell responses during primary infection and during re-infection is not fully elucidated. We describe a second peak of pro-inflammatory mediators during the primary immune response to RSV that coincides with the arrival of T cells into the lung. This second peak of cytokines/chemokines is regulated differently than the early peak and is largely independent of signaling via MAVS. This was concurrent with Mavs−/− mice mounting a strong T cell response to primary RSV infection, with robust IFN-γ; and Granzyme B production. However, after RSV re-infection, Mavs−/− mice showed fewer CD4+ and CD8+ short term memory T cells and their capacity to produce IFN-γ; and Granzyme B, was decreased. In sum, cytosolic recognition of RSV is important not only for initiating innate anti-viral responses but also for generating or maintaining efficient, short term T cell memory responses.

Immune response to respiratory syncytial virus infection (&lt;i&gt;Orthopneumovirus&lt;/i&gt;)

Respiratory syncytial virus (RSV) infects children as well as elderly and immunocompromised subjects. In 2016, RSV was renamed to Orthopneumovirus owing to virus taxonomy latinization and was also included into the Pneumoviridae family. However, in this review we will use the old and more common RSV name. RSV infection may occur throughout human lifetime as it does not induce sterilizing immunity. During RSV infection, diverse immune cells such as dendritic cells, macrophages, T cells, B cells and eosinophils are involved in the antiviral response. Some of them play an important role in eliminating RSV, while the others can provoke tissue damage. An interaction between these cells occurs through the induced cytokines and chemokines, some of which emerge at early disease stages, whereas the others — at later stages. In addition, the mentioned cells can affect the course of both primary and secondary RSV infection. A prolonged or persistent RSV infection is observed in children with T-cell immunodeficiency, emphasizing the importance of T cells in resolution of acute infection as well as for virus-specific immunological memory development. Almost all the adults and children bear RSV-specific antibodies, but that doesn't protect against the repeated infection. It was shown that high mucosal rather than serum IgG level correlated better with reduced RSV load. A growing body of RSV vaccine candidates has emerged: live-attenuated, protein-based, whole-inactivated, particle-based, subunit antigens, and nucleic acid-based vaccines. While developing vaccines, there should be taken into consideration features of anti-RSV immune response as well as age of subjects to be vaccinated. In particular, to avoid vaccine-associated aggravation of RSV infection it is justified to use live attenuated vaccines in children, whereas middle-aged and the elderly subjects might be applied with subunit vaccines. Currently, no licensed vaccine for RSV infection is available. In this review, we will detail an interaction of the RSV with diverse immune cells as well as our contemporary understanding regarding preventive vaccines in RSV infection.

Estimating the burden of respiratory syncytial virus infection in young children in England: a novel approach to community-based serological surveys through data linkage

BackgroundBronchiolitis caused by respiratory syncytial virus (RSV) is the most common reason for hospital admissions in infants. The community burden of RSV is less well understood. We used a unique dataset linking serial serological data, questionnaires, and routinely collected health records to undertake the first community-based serological survey of RSV in England. MethodsWe used stored blood samples, tested for immunoglobulin G RSV postfusion F antibody, linked to questionnaires and primary and secondary care records from the Born in Bradford cohort study, collected at birth, and ages 1 and 2 years. We used finite mixture models to classify children as RSV infected or not infected according to their antibody concentrations. We fitted multivariable Poisson regression models with robust error variances to identify factors associated with increased risk of primary RSV infection at ages younger than 1 year and 1–2 years. FindingsThe study included 490 children. By their first birthday, 258 children (53%, 95% CI 48–57%) had serological evidence of past RSV infection, 99 (38%) of whom contacted health-care services during peak RSV season (November–January) due to a respiratory tract infection. Having older siblings (adjusted risk ratio [aRR] 1·52, 95% CI 1·21–1·92, comparing one to no older siblings), Pakistani ethnicity (1·31, 1·04–1·65, compared with White British), blood sample taken outside October–December (1·74, 1·35–2·24 for January–March and 1·60, 1·23–2·08 for April–June, compared with October–December), and attending formal childcare (1·40, 1·12–1·75, compared with no formal childcare) were predictive of RSV infection in infancy. A further 164 children (33%, 95% CI 29–38%) were newly infected at ages 1–2 years, 58 (35%) of whom had contact with health-care services. 14% (95% CI 11–17%) had no evidence of RSV infection by age 2 years. InterpretationAround half of children are infected with RSV during the first year of life, and one in seven children remain unexposed after their second year. Our findings will inform future analyses to assess the cost-effectiveness of RSV vaccination programmes. Our novel approach reusing stored blood samples and linked data present a time-efficient and cheap method for future serological surveys of RSV. FundingWellcome Trust Seed Award In Science (grant reference number 207673/Z/17/Z).

Respiratory Syncytial Virus Vaccines: Are We Making Progress?

Respiratory Syncytial Virus Vaccines: Are We Making Progress?

Aims, Study Design, and Enrollment Results From the Assessing Predictors of Infant Respiratory Syncytial Virus Effects and Severity Study.

BackgroundThe majority of infants hospitalized with primary respiratory syncytial virus (RSV) infection have no obvious risk factors for severe disease.ObjectiveThe aim of this study (Assessing Predictors of Infant RSV Effects and Severity, AsPIRES) was to identify factors associated with severe disease in full-term healthy infants younger than 10 months with primary RSV infection.MethodsRSV infected infants were enrolled from 3 cohorts during consecutive winters from August 2012 to April 2016 in Rochester, New York. A birth cohort was prospectively enrolled and followed through their first winter for development of RSV infection. An outpatient supplemental cohort was enrolled in the emergency department or pediatric offices, and a hospital cohort was enrolled on admission with RSV infection. RSV was diagnosed by reverse transcriptase-polymerase chain reaction. Demographic and clinical data were recorded and samples collected for assays: buccal swab (cytomegalovirus polymerase chain reaction, PCR), nasal swab (RSV qualitative PCR, complete viral gene sequence, 16S ribosomal ribonucleic acid [RNA] amplicon microbiota analysis), nasal wash (chemokine and cytokine assays), nasal brush (nasal respiratory epithelial cell gene expression using RNA sequencing [RNAseq]), and 2 to 3 ml of heparinized blood (flow cytometry, RNAseq analysis of purified cluster of differentiation [CD]4+, CD8+, B cells and natural killer cells, and RSV-specific antibody). Cord blood (RSV-specific antibody) was also collected for the birth cohort. Univariate and multivariate logistic regression will be used for analysis of data using a continuous Global Respiratory Severity Score (GRSS) as the outcome variable. Novel statistical methods will be developed for integration of the large complex datasets.ResultsA total of 453 infants were enrolled into the 3 cohorts; 226 in the birth cohort, 60 in the supplemental cohort, and 78 in the hospital cohort. A total of 126 birth cohort infants remained in the study and were evaluated for 150 respiratory illnesses. Of the 60 RSV positive infants in the supplemental cohort, 42 completed the study, whereas all 78 of the RSV positive hospital cohort infants completed the study. A GRSS was calculated for each RSV-infected infant and is being used to analyze each of the complex datasets by correlation with disease severity in univariate and multivariate methods.ConclusionsThe AsPIRES study will provide insights into the complex pathogenesis of RSV infection in healthy full-term infants with primary RSV infection. The analysis will allow assessment of multiple factors potentially influencing the severity of RSV infection including the level of RSV specific antibodies, the innate immune response of nasal epithelial cells, the adaptive response by various lymphocyte subsets, the resident airway microbiota, and viral factors. Results of this study will inform disease interventions such as vaccines and antiviral therapies.