The genomic evolutionary dynamics and global circulation patterns of respiratory syncytial virus

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection in young children and the second leading cause of infant death worldwide. While global circulation has been extensively studied for respiratory viruses such as seasonal influenza, and more recently also in great detail for SARS-CoV-2, a lack of global multi-annual sampling of complete RSV genomes limits our understanding of RSV molecular epidemiology. Here, we capitalise on the genomic surveillance by the INFORM-RSV study and apply phylodynamic approaches to uncover how selection and neutral epidemiological processes shape RSV diversity. Using complete viral genome sequences, we show similar patterns of site-specific diversifying selection among RSVA and RSVB and recover the imprint of non-neutral epidemic processes on their genealogies. Using a phylogeographic approach, we provide evidence for air travel governing the global patterns of RSVA and RSVB spread, which results in a considerable degree of phylogenetic mixing across countries. Our findings highlight the potential of systematic global RSV genomic surveillance for transforming our understanding of global RSV spread.

Fc-mediated functions of nirsevimab complement direct respiratory syncytial virus neutralization but are not required for optimal prophylactic protection

Introduction

Nirsevimab is an extended half-life (M252Y/S254T/T256E [YTE]-modified) monoclonal antibody to the pre-fusion conformation of the respiratory syncytial virus (RSV) Fusion protein, with established efficacy in preventing RSV-associated lower respiratory tract infection in infants for the duration of a typical RSV season. Previous studies suggest that nirsevimab confers protection via direct virus neutralization. Here we use preclinical models to explore whether fragment crystallizable (Fc)-mediated effector functions contribute to nirsevimab-mediated protection.

Methods

Nirsevimab, MEDI8897* (i.e., nirsevimab without the YTE modification), and MEDI8897*-TM (i.e., MEDI8897* without Fc effector functions) binding to Fc γ receptors (FcγRs) was evaluated using surface plasmon resonance. Antibody-dependent neutrophil phagocytosis (ADNP), antibody-dependent cellular phagocytosis (ADCP), antibody-dependent complement deposition (ADCD), and antibody-dependent cellular cytotoxicity (ADCC) were assessed through in vitro and ex vivo serological analyses. A cotton rat challenge study was performed with MEDI8897* and MEDI8897*-TM to explore whether Fc effector functions contribute to protection from RSV.

Results

Nirsevimab and MEDI8897* exhibited binding to a range of FcγRs, with expected reductions in FcγR binding affinities observed for MEDI8897*-TM. Nirsevimab exhibited in vitro ADNP, ADCP, ADCD, and ADCC activity above background levels, and similar ADNP, ADCP, and ADCD activity to palivizumab. Nirsevimab administration increased ex vivo ADNP, ADCP, and ADCD activity in participant serum from the MELODY study (NCT03979313). However, ADCC levels remained similar between nirsevimab and placebo. MEDI8897* and MEDI8897*-TM exhibited similar dose-dependent reduction in lung and nasal turbinate RSV titers in the cotton rat model.

Conclusion

Nirsevimab possesses Fc effector activity comparable with the current standard of care, palivizumab. However, despite possessing the capacity for Fc effector activity, data from RSV challenge experiments illustrate that nirsevimab-mediated protection is primarily dependent on direct virus neutralization.

Molecular and phenotypic characteristics of RSV infections in infants during two nirsevimab randomized clinical trials

Nirsevimab is a monoclonal antibody that binds to the respiratory syncytial virus (RSV) fusion protein. During the Phase 2b (NCT02878330) and MELODY (NCT03979313) clinical trials, infants received one dose of nirsevimab or placebo before their first RSV season. In this pre-specified analysis, isolates from RSV infections were subtyped, sequenced and analyzed for nirsevimab binding site substitutions; subsequently, recombinant RSVs were engineered for microneutralization susceptibility testing. Here we show that the frequency of infections caused by subtypes A and B is similar across and within the two trials. In addition, RSV A had one and RSV B had 10 fusion protein substitutions occurring at >5% frequency. Notably, RSV B binding site substitutions were rare, except for the highly prevalent I206M:Q209R, which increases nirsevimab susceptibility; RSV B isolates from two participants had binding site substitutions that reduce nirsevimab susceptibility. Overall, >99% of isolates from the Phase 2b and MELODY trials retained susceptibility to nirsevimab.

Nirsevimab binding-site conservation in respiratory syncytial virus fusion glycoprotein worldwide between 1956 and 2021: an analysis of observational study sequencing data

BACKGROUND

Nirsevimab is an extended half-life monoclonal antibody to the respiratory syncytial virus (RSV) fusion protein that has been developed to protect infants for an entire RSV season. Previous studies have shown that the nirsevimab binding site is highly conserved. However, investigations of the geotemporal evolution of potential escape variants in recent (ie, 2015-2021) RSV seasons have been minimal. Here, we examine prospective RSV surveillance data to assess the geotemporal prevalence of RSV A and B, and functionally characterise the effect of the nirsevimab binding-site substitutions identified between 2015 and 2021.

METHODS

We assessed the geotemporal prevalence of RSV A and B and nirsevimab binding-site conservation between 2015 and 2021 from three prospective RSV molecular surveillance studies (the US-based OUTSMART-RSV, the global INFORM-RSV, and a pilot study in South Africa). Nirsevimab binding-site substitutions were assessed in an RSV microneutralisation susceptibility assay. We contextualised our findings by assessing fusion-protein sequence diversity from 1956 to 2021 relative to other respiratory-virus envelope glycoproteins using RSV fusion protein sequences published in NCBI GenBank.

FINDINGS

We identified 5675 RSV A and RSV B fusion protein sequences (2875 RSV A and 2800 RSV B) from the three surveillance studies (2015-2021). Nearly all (25 [100%] of 25 positions of RSV A fusion proteins and 22 [88%] of 25 positions of RSV B fusion proteins) amino acids within the nirsevimab binding site remained highly conserved between 2015 and 2021. A highly prevalent (ie, >40·0% of all sequences) nirsevimab binding-site Ile206Met:Gln209Arg RSV B polymorphism arose between 2016 and 2021. Nirsevimab neutralised a diverse set of recombinant RSV viruses, including new variants containing binding-site substitutions. RSV B variants with reduced susceptibility to nirsevimab neutralisation were detected at low frequencies (ie, prevalence <1·0%) between 2015 and 2021. We used 3626 RSV fusion-protein sequences published in NCBI GenBank between 1956 and 2021 (2024 RSV and 1602 RSV B) to show that the RSV fusion protein had lower genetic diversity than influenza haemagglutinin and SARS-CoV-2 spike proteins.

INTERPRETATION

The nirsevimab binding site was highly conserved between 1956 and 2021. Nirsevimab escape variants were rare and have not increased over time.

FUNDING

AstraZeneca and Sanofi.

Durability of neutralizing RSV antibodies following nirsevimab administration and elicitation of the natural immune response to RSV infection in infants

Nirsevimab is an extended half-life monoclonal antibody specific for the prefusion conformation of the respiratory syncytial virus (RSV) F protein, which has been studied in preterm and full-term infants in the phase 2b and phase 3 MELODY trials. We analyzed serum samples collected from 2,143 infants during these studies to characterize baseline levels of RSV-specific immunoglobulin G antibodies and neutralizing antibodies (NAbs), duration of RSV NAb levels following nirsevimab administration, the risk of RSV exposure during the first year of life and the infant's adaptive immune response to RSV following nirsevimab administration. Baseline RSV antibody levels varied widely; consistent with reports that maternal antibodies are transferred late in the third trimester, preterm infants had lower baseline RSV antibody levels than full-term infants. Nirsevimab recipients had RSV NAb levels >140-fold higher than baseline at day 31 and remained >50-fold higher at day 151 and >7-fold higher at day 361. Similar seroresponse rates to the postfusion form of RSV F protein in nirsevimab recipients (68-69%) compared with placebo recipients (63-70%; not statistically significant) suggest that while nirsevimab protects from RSV disease, it still allows an active immune response. In summary, nirsevimab provided sustained, high levels of NAb throughout an infant's first RSV season and prevented RSV disease while allowing the development of an immune response to RSV.

AZD1222-induced nasal antibody responses are shaped by prior SARS-CoV-2 infection and correlate with virologic outcomes in breakthrough infection

The nasal mucosa is an important initial site of host defense against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, intramuscularly administered vaccines typically do not achieve high antibody titers in the nasal mucosa. We measure anti-SARS-CoV-2 spike immunoglobulin G (IgG) and IgA in nasal epithelial lining fluid (NELF) following intramuscular vaccination of 3,058 participants from the immunogenicity substudy of a phase 3, double-blind, placebo-controlled study of AZD1222 vaccination (ClinicalTrials.gov: NCT04516746). IgG is detected in NELF collected 14 days following the first AZD1222 vaccination. IgG levels increase with a second vaccination and exceed pre-existing levels in baseline-SARS-CoV-2-seropositive participants. Nasal IgG responses are durable and display strong correlations with serum IgG, suggesting serum-to-NELF transudation. AZD1222 induces short-lived increases to pre-existing nasal IgA levels in baseline-seropositive vaccinees. Vaccinees display a robust recall IgG response upon breakthrough infection, with overall magnitudes unaffected by time between vaccination and illness. Mucosal responses correlate with reduced viral loads and shorter durations of viral shedding in saliva.

Robust humoral and cellular recall responses to AZD1222 attenuate breakthrough SARS-CoV-2 infection compared to unvaccinated

Background

Breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in coronavirus disease 2019 (COVID-19) vaccinees typically produces milder disease than infection in unvaccinated individuals.

Methods

To explore disease attenuation, we examined COVID-19 symptom burden and immuno-virologic responses to symptomatic SARS-CoV-2 infection in participants (AZD1222: n=177/17,617; placebo: n=203/8,528) from a 2:1 randomized, placebo-controlled, phase 3 study of two-dose primary series AZD1222 (ChAdOx1 nCoV-19) vaccination (NCT04516746).

Results

We observed that AZD1222 vaccinees had an overall lower incidence and shorter duration of COVID-19 symptoms compared with placebo recipients, as well as lower SARS-CoV-2 viral loads and a shorter median duration of viral shedding in saliva. Vaccinees demonstrated a robust antibody recall response versus placebo recipients with low-to-moderate inverse correlations with virologic endpoints. Vaccinees also demonstrated an enriched polyfunctional spike-specific Th-1-biased CD4+ and CD8+ T-cell response that was associated with strong inverse correlations with virologic endpoints.

Conclusion

Robust immune responses following AZD1222 vaccination attenuate COVID-19 disease severity and restrict SARS-CoV-2 transmission potential by reducing viral loads and the duration of viral shedding in saliva. Collectively, these analyses underscore the essential role of vaccination in mitigating the COVID-19 pandemic.

1953. Immune responses, viral shedding, and COVID-19 symptom burden from breakthrough SARS-CoV-2 infection in a 2:1 randomized, double-blind, placebo-controlled Phase 3 study of AZD1222 (ChAdOx1 nCoV-19) vaccination

Background

Breakthrough infections post-COVID-19 vaccination increase with waning immunity and typically produce milder disease than infections in unvaccinated individuals. We investigated immuno-virologic responses and COVID-19 symptom burden upon breakthrough infection in participants from a Phase 3 study of 2-dose primary series AZD1222 vaccination (NCT04516746) to explore disease attenuation.

Methods

Study participants who experienced protocol-defined COVID-19 symptoms initiated a series of illness visits over 28 days with collection of sera, nasopharyngeal (NP) swabs and saliva samples (SS), and documentation of symptoms (data-cut off: July 30, 2021). For baseline-seronegative participants with PCR-confirmed SARS-CoV-2 infection ≥15 days after dose 2 of AZD1222 or placebo we assessed: anti-SARS-CoV-2 spike (S), nucleocapsid (N) and neutralizing antibody (Ab) titers by multiplex immunoassay and SARS-CoV-2 pseudovirus assay in sera; viral load by quantitative RT-PCR in NP swabs; and viral shedding by qualitative and quantitative RT-PCR in SS. Data were stratified by age and SARS-CoV-2 variant, and time since primary series dose 2.

Results

Illness Day 1 (ILL-D1) S Ab GMTs in AZD1222 vaccinees were similar to peak GMTs seen 14 days after dose 2 of AZD1222 and were higher vs placebo at all timepoints. The magnitude of S Ab response differed by age: median GMTs were lower at ILL-D1 and higher at ILL-D14 in vaccinees aged ≥65 vs 18–64 years (Fig.1). ILL-D1 overall, SARS-CoV-2 ancestral, alpha, and epsilon variant viral load titers in NP swabs were lower in vaccinees vs placebo (Fig 2). Mean viral load in NP swabs and viral shedding titers in SS were lower in vaccinees vs placebo at all timepoints. Vaccinees reported fewer COVID-19 symptoms than placebo participants, and experienced shorter symptom duration, particularly for fatigue and difficulty breathing.

Figure 1. SARS-CoV-2 spike IgG antibody titers upon SARS-CoV-2 infection by participant age in AZD1222 vaccinees and placebo recipients during illness visits Figure 2. Quantification of viral load (nasopharyngeal swabs quantitative viral titer) by SARS-CoV-2 variant at Illness Visit Day 1

Conclusion

Improved S Ab responses, lower viral loads, and reduced symptom burden upon breakthrough infection in vaccinees vs placebo recipients, suggest that robust recall responses to AZD1222 vaccination may attenuate COVID-19 disease severity and duration. These findings alongside data on cellular immune responses to breakthrough infection will inform understanding of protective immunity to SARS-CoV-2 infection.

Disclosures

Magdalena E. Sobieszczyk, MD, MPH, Bill and Melinda Gates Foundation: Grant/Research Support|Gilead Sciences: Grant/Research Support|Janssen Global Services, LLC: Grant/Research Support|Merck: Grant/Research Support|National Institute of Allergy and Infectious Diseases (NIAID): Grant/Research Support|National Institutes of Health (NIH): Grant/Research Support|Sanofi Pasteur Inc.: Grant/Research Support Ann R. Falsey, MD, BioFire Diagnostics: Grant/Research Support|Janssen: Grant/Research Support|Merck, Sharp and Dohme: Grant/Research Support|Novavax: Advisor/Consultant|Pfizer: Grant/Research Support Anne F. Luetkemeyer, MD, AstraZeneca: Grant/Research Support|Gilead Sciences: Grant/Research Support Grant C. Paulsen, MD, AstraZeneca: Grant/Research Support|Moderna: Grant/Research Support|Pfizer: Grant/Research Support Sharon A. Riddler, MD, National Institute of Allergy and Infectious Diseases (NIAID): Grant/Research Support|National Institutes of Health (NIH): Grant/Research Support|Novimmune: Advisor/Consultant Merlin L. Robb, MD, Walter Reed Army Institute of Research: Advisor/Consultant Charlotte-Paige M. Rolle, MD, MPH, Gilead Sciences: Board Member|Gilead Sciences: Grant/Research Support|Gilead Sciences: Honoraria|Janssen: Board Member|ViiV Healthcare: Board Member|ViiV Healthcare: Grant/Research Support|ViiV Healthcare: Honoraria|Vindico CME: Honoraria Beverly E. Sha, MD, Gilead Sciences: Grant/Research Support|MATEC: Honoraria|University of Chicago: Grant/Research Support|US Government: Grant/Research Support Bahar Ahani, BSC, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Anastasia A. Aksyuk, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Himanshu Bansal, MS, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Justin A. Green, MD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Brett Jepson, MS, AstraZeneca: Contractor via Cytel Jill Maaske, MD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Kathryn Shoemaker, MS, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Stephanie Sproule, MMath, AstraZeneca: Contractor via Joule/System One Ann Marie Stanley, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Deidre Wilkins, BSC, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Tonya L. Villafana, PhD, MPH, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Elizabeth J. Kelly, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds.

94. Pooled analysis of nirsevimab resistance through 150 days post dose in preterm and term infants

Background

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection (LRTI) and hospitalization in infants. In two global pivotal placebo-controlled studies, nirsevimab, a monoclonal antibody to the RSV prefusion (F) protein with extended half-life, reduced medically attended (MA) RSV LRTI versus placebo throughout the RSV season (MELODY (Primary Cohort)/Study 3 (Proposed Dose) Pool, 79.5% efficacy). Here we summarize resistance analyses of all RT-PCR-confirmed RSV isolates from healthy term and preterm infants through 150 days post dose.

Methods

Infants were randomized 2:1 to receive one intramuscular injection of nirsevimab or placebo, prior to their first RSV season. RT-PCR-confirmed RSV isolates were reflexed for genotypic analyses of RSV F and phenotypic analyses of identified substitutions in a recombinant RSV neutralization susceptibility assay.

Results

In the pooled proposed dose analysis of Study 3 (50 mg nirsevimab if < 5 kg at dosing) and MELODY (50 or 100 mg nirsevimab if < 5 kg or ≥5 kg at dosing, respectively), no subject with MA RSV LRTI had an RSV isolate containing nirsevimab resistance-associated substitutions in either treatment group (nirsevimab, RSV A: 0/14 and RSV B: 0/5; placebo, RSV A: 0/35 and RSV B: 0/16). In Study 3 (50 mg nirsevimab if ≥5 kg at dosing), 2/18 subjects in the nirsevimab group and 0/20 subjects in the placebo group with MA RSV LRTI had an RSV isolate harbouring nirsevimab binding site substitutions I64T+K68E+I206M+Q209R (>447-fold) or N208S (>387-fold) that conferred reduced susceptibility to nirsevimab neutralization (nirsevimab, RSV A: 0/9 and RSV B: 2/9; placebo, RSV A: 0/10 and RSV B: 0/10). Subjects with RSV isolates harboring F protein sequence variations that maintained susceptibility to nirsevimab neutralization were balanced between treatment groups with no association with RSV disease severity. No subjects with non-protocol defined MA RSV LRTI cases or hospitalization due to any RSV respiratory illness had an RSV isolate conferring nirsevimab resistance.

Conclusion

Lack of nirsevimab resistance following immunization at the proposed dose supports efficacy and neutralization activity of nirsevimab against both RSV A and B strains throughout the RSV season.

Disclosures

Michael E. Abram, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Bahar Ahani, BSC, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds David E. Tabor, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Fiona Fernandes, PhD, AstraZeneca: Stocks/Bonds Deidre Wilkins, BSC, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Anastasia A. Aksyuk, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Kevin M. Tuffy, MS, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Hong Ji, BSc, AstraZeneca: Stocks/Bonds Christine Blaze, BSc, AstraZeneca: Stocks/Bonds Tyler Brady, MS, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Pamela Griffin, MD, AstraZeneca: Stocks/Bonds Amanda Leach, MD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Tonya L. Villafana, PhD, MPH, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Mark T. Esser, PhD, AstraZeneca: Stocks/Bonds.

Tolerability and immunogenicity of an intranasally-administered adenovirus-vectored COVID-19 vaccine: An open-label partially-randomised ascending dose phase I trial

BACKGROUND

Intranasal vaccination may induce protective local and systemic immune responses against respiratory pathogens. A number of intranasal SARS-CoV-2 vaccine candidates have achieved protection in pre-clinical challenge models, including ChAdOx1 nCoV-19 (AZD1222, University of Oxford / AstraZeneca).

METHODS

We performed a single-centre open-label Phase I clinical trial of intranasal vaccination with ChAdOx1 nCoV-19 in healthy adults, using the existing formulation produced for intramuscular administration. Thirty SARS-CoV-2 vaccine-naïve participants were allocated to receive 5 × 10⁹ viral particles (VP, n=6), 2 × 10¹⁰ VP (n=12), or 5 × 10¹⁰ VP (n=12). Fourteen received second intranasal doses 28 days later. A further 12 received non-study intramuscular mRNA SARS-CoV-2 vaccination between study days 22 and 46. To investigate intranasal ChAdOx1 nCoV-19 as a booster, six participants who had previously received two intramuscular doses of ChAdOx1 nCoV-19 and six who had received two intramuscular doses of BNT162b2 (Pfizer / BioNTech) were given a single intranasal dose of 5 × 10¹⁰ VP of ChAdOx1 nCoV-19. Objectives were to assess safety (primary) and mucosal antibody responses (secondary).

FINDINGS

Reactogenicity was mild or moderate. Antigen-specific mucosal antibody responses to intranasal vaccination were detectable in a minority of participants, rarely exceeding levels seen after SARS-CoV-2 infection. Systemic responses to intranasal vaccination were typically weaker than after intramuscular vaccination with ChAdOx1 nCoV-19. Antigen-specific mucosal antibody was detectable in participants who received an intramuscular mRNA vaccine after intranasal vaccination. Seven participants developed symptomatic SARS-CoV-2 infection.

INTERPRETATION

This formulation of intranasal ChAdOx1 nCoV-19 showed an acceptable tolerability profile but induced neither a consistent mucosal antibody response nor a strong systemic response.

FUNDING

AstraZeneca.

Validation and performance of a multiplex serology assay to quantify antibody responses following SARS-CoV-2 infection or vaccination

Objectives

Robust, quantitative serology assays are required to accurately measure antibody levels following vaccination and natural infection. We present validation of a quantitative, multiplex, SARS‐CoV‐2, electrochemiluminescent (ECL) serology assay; show correlation with two established SARS‐CoV‐2 immunoassays; and present calibration results for two SARS‐CoV‐2 reference standards.

Methods

Precision, dilutional linearity, ruggedness, analytical sensitivity and specificity were evaluated. Clinical sensitivity and specificity were assessed using serum from prepandemic and SARS‐CoV‐2 polymerase chain reaction (PCR)‐positive patient samples. Assay concordance to the established Roche Elecsys® Anti‐SARS‐CoV‐2 immunoassay and a live‐virus microneutralisation (MN) assay was evaluated.

Results

Standard curves demonstrated the assay can quantify SARS‐CoV‐2 antibody levels over a broad range. Assay precision (10.2−15.1% variability), dilutional linearity (≤ 1.16‐fold bias per 10‐fold increase in dilution), ruggedness (0.89−1.18 overall fold difference), relative accuracy (107−118%) and robust selectivity (102−104%) were demonstrated. Analytical sensitivity was 7, 13 and 7 arbitrary units mL⁻¹ for SARS‐CoV‐2 spike (S), receptor‐binding domain (RBD) and nucleocapsid (N) antigens, respectively. For all antigens, analytical specificity was > 90% and clinical specificity was 99.0%. Clinical sensitivities for S, RBD and N antigens were 100%, 98.8% and 84.9%, respectively. Comparison with the Elecsys® immunoassay showed ≥ 87.7% agreement and linear correlation (Pearson r of 0.85, P < 0.0001) relative to the MN assay. Conversion factors for the WHO International Standard and Meso Scale Discovery® Reference Standard are presented.

Conclusions

The multiplex SARS‐CoV‐2 ECL serology assay is suitable for efficient, reproducible measurement of antibodies to SARS‐CoV‐2 antigens in human sera, supporting its use in clinical trials and sero‐epidemiology studies.

Global molecular diversity of RSV - the "INFORM RSV" study

Background

Respiratory syncytial virus (RSV) is a global cause of severe respiratory morbidity and mortality in infants. While preventive and therapeutic interventions are being developed, including antivirals, vaccines and monoclonal antibodies, little is known about the global molecular epidemiology of RSV. INFORM is a prospective, multicenter, global clinical study performed by ReSViNET to investigate the worldwide molecular diversity of RSV isolates collected from children less than 5 years of age.

Methods

The INFORM study is performed in 17 countries spanning all inhabited continents and will provide insight into the molecular epidemiology of circulating RSV strains worldwide. Sequencing of > 4000 RSV-positive respiratory samples is planned to detect temporal and geographical molecular patterns on a molecular level over five consecutive years. Additionally, RSV will be cultured from a subset of samples to study the functional implications of specific mutations in the viral genome including viral fitness and susceptibility to different monoclonal antibodies.

Discussion

The sequencing and functional results will be used to investigate susceptibility and resistance to novel RSV preventive or therapeutic interventions. Finally, a repository of globally collected RSV strains and a database of RSV sequences will be created.

Characterization of human respiratory syncytial virus (RSV) isolated from HIV-exposed-uninfected and HIV-unexposed infants in South Africa during 2015-2017

BACKGROUND

RSV is a leading cause of lower respiratory tract infection in infants. Monitoring RSV glycoprotein sequences is critical for understanding RSV epidemiology and viral antigenicity in the effort to develop anti-RSV prophylactics and therapeutics.

OBJECTIVES

The objective is to characterize the circulating RSV strains collected from infants in South Africa during 2015-2017.

METHODS

A subset of 150 RSV-positive samples obtained in South Africa from HIV-unexposed and HIV-exposed-uninfected infants from 2015 to 2017, were selected for high-throughput next-generation sequencing of the RSV F and G glycoprotein genes. The RSV G and F sequences were analyzed by a bioinformatic pipeline and compared to the USA samples from the same three-year period.

RESULTS

Both RSV A and RSV B co-circulated in South Africa during 2015-2017, with a shift from RSV A (58%-61% in 2015-2016) to RSV B (69%) in 2017. RSV A ON1 and RSV B BA9 genotypes emerged as the most prevalent genotypes in 2017. Variations at the F protein antigenic sites were observed for both RSV A and B strains, with dominant changes (L172Q/S173L) at antigenic site V observed in RSV B strains. RSV A and B F protein sequences from South Africa were very similar to the USA isolates except for a higher rate of RSV A NA1 and RSV B BA10 genotypes in South Africa.

CONCLUSION

RSV G and F genes continue to evolve and exhibit both local and global circulation patterns in South Africa, supporting the need for continued national surveillance.

Modelling of vapour intrusion into a building impacted by a fuel spill in Antarctica

A new vapour intrusion contaminant transport model was designed specifically to allow an assessment of the impact of a hydrocarbon fuel spill on air quality in cold region buildings. The model is applied to a recent situation in Antarctica, where a diesel spill impacted the construction of a new building. For the first time, this model allows consideration of the diffusive resistance of different vapour barrier to the transport of hydrocarbons into the building and an assessment of the effectiveness of different products. Site specific indoor air criteria are derived. Five scenarios are modelled at field temperatures: (1) build on current contaminated site; (2) excavate contaminated soil, backfill with clean soil and assess impact of residual contamination; (3) excavate and backfill with remediated (biopile) soil; (4) backfill with remediated soil and assess impact of residual contamination; (5) backfill with remediated soil and assess impact of a potential future fuel spill. Two different vapour barriers, a co-extruded ethylene vinyl alcohol (EVOH) geomembrane (VB1) and a linear low-density (LLDPE) geomembrane (VB2), are investigated for each scenario and compared to a base case with no vapour barrier, providing quantifiable evidence of the benefit of installing an engineered vapour barrier Contaminant concentrations were below regulatory limits for Scenarios (2-5) with VB1 and air exchange in the building. For all scenarios, the EVOH geomembrane (VB1) was consistently superior at reducing vapour transport into the building indoor air space over the LLDPE geomembrane (VB2) and no vapour barrier. The risk mitigation measures developed for this contaminated Antarctic site may be relevant for other buildings in cold regions.

Military health outreach on Exercise ASKARI SERPENT: a discussion of clinical and ethical challenges

Exercise ASKARI SERPENT (Ex AS) is an annual British Army medical exercise that sees the deployment of a medical regiment to rural Kenya. The exercise involves the delivery of health outreach clinics and health education to the civilian population alongside Kenyan governmental and non-governmental organisations. This article includes a post hoc analysis of the ethical and clinical challenges that clinicians faced during Ex AS, applying a four-quadrant approach to ethical decision-making. This article intends to stimulate further debate and discussion on how to best prepare clinicians for clinical challenges and ethical decision-making on future exercises and operations. We conclude that our experiences on Ex AS can provide an insight on how to develop predeployment training for clinicians. Furthermore, the universal nature of the challenges faced on Ex AS can be applied to training for future contingency operations.

Contributory factors in surgical incidents as delineated by a confidential reporting system

Background Confidential reporting systems play a key role in capturing information about adverse surgical events. However, the value of these systems is limited if the reports that are generated are not subjected to systematic analysis. The aim of this study was to provide the first systematic analysis of data from a novel surgical confidential reporting system to delineate contributory factors in surgical incidents and document lessons that can be learned. Methods One-hundred and forty-five patient safety incidents submitted to the UK Confidential Reporting System for Surgery over a 10-year period were analysed using an adapted version of the empirically-grounded Yorkshire Contributory Factors Framework. Results The most common factors identified as contributing to reported surgical incidents were cognitive limitations (30.09%), communication failures (16.11%) and a lack of adherence to established policies and procedures (8.81%). The analysis also revealed that adverse events were only rarely related to an isolated, single factor (20.71%) - with the majority of cases involving multiple contributory factors (79.29% of all cases had more than one contributory factor). Examination of active failures - those closest in time and space to the adverse event - pointed to frequent coupling with latent, systems-related contributory factors. Conclusions Specific patterns of errors often underlie surgical adverse events and may therefore be amenable to targeted intervention, including particular forms of training. The findings in this paper confirm the view that surgical errors tend to be multi-factorial in nature, which also necessitates a multi-disciplinary and system-wide approach to bringing about improvements.

On site remediation of a fuel spill and soil reuse in Antarctica

The first large-scale remediation of fuel contamination in Antarctica treated 10000L of diesel dispersed in 1700t of soil, and demonstrated the efficacy of on-site bioremediation. The project progressed through initial site assessment and natural attenuation, passive groundwater management, then active remediation and the managed reuse of soil. Monitoring natural attenuation for the first 12years showed contaminant levels in surface soil remained elevated, averaging 5000mg/kg. By contrast, in five years of active remediation (excavation and biopile treatment) contaminant levels decreased by a factor of four. Chemical indicators showed hydrocarbon loss was apportioned to both biodegradation and evaporative processes. Hydrocarbon degradation rates were assessed against biopile soil temperatures, showing a phase of rapid degradation (first 100days above soil temperature threshold of 0°C) followed by slower degradation (beyond 100days above threshold). The biopiles operated successfully within constraints typical of harsh climates and remote sites, including limitations on resources, no external energy inputs and short field seasons. Non-native microorganisms (e.g. inoculations) and other organic materials (e.g. bulking agents) are prohibited in Antarctica making this cold region more challenging for remediation than the Arctic. Biopile operations included an initial fertiliser application, biannual mechanical turning of the soil and minimal leachate recirculation. The biopiles are a practical approach to remediate large quantities of contaminated soil in the Antarctic and already 370t have been reused in a building foundation. The findings presented demonstrate that bioremediation is a viable strategy for Antarctica and other cold regions. Operators can potentially use the modelled relationship between days above 0°C (threshold temperature) and the change in degradation rates to estimate how long it would take to remediate other sites using the biopile technology with similar soil and contaminant types.

Mapping health events - a comparison of approaches

The Waikato Regional Public Health Unit (New Zealand) collects and maintains a database of notified health events that includes communicable diseases. This database can be used by health protection officers to identify problem areas that have unusually high incidences of events. Resources can then be targeted and officers can respond accordingly. However, for this data to be useful it needs to be represented as a rate of health events per 100,000 people. This paper investigates the use of Geographic Information Systems (GIS) to visualize and represent these data. Standard vector representations that use census area units are compared with raster representations that use focal neighbourhood functions. The two techniques produce rates of health events that differ by up to 100 per cent for a given location and scale. The vector technique is the standard approach and is easily understood. The raster technique enables more control over the scale of analysis and can provide a more spatially accurate representation of health events. If two techniques can produce such large differences in analysis results, it is important that health protection officers and epidemiologists give special consideration to the representation technique used.

Protein-Derived Acetaminophen-Cysteine Can Be Detected After Repeated Supratherapeutic Ingestion of Acetaminophen in the Absence of Hepatotoxicity

Generation of protein-derived acetaminophen-cysteine (APAP-CYS) is reported after ingestion of large and therapeutic dosages of acetaminophen in healthy and in liver-damaged patients. The incidence of protein-derived APAP-CYS adducts in repeated supratherapeutic dosages of APAP is not known.

METHODS

for 12 months, a standardized and comprehensive questionnaire was used to interview every consecutive patient at a pain management clinic. Patients found to ingest more than 4 g of APAP per day for a minimum of 14 consecutive days at the time of the encounter were invited to have blood drawn for hepatic transaminases and APAP-CYS adduct levels. Twelve subjects out of 990 interviewees met inclusion criteria. Ten of the 12 had measurable protein-derived APAP-CYS, none had evidence of liver injury. Patients that ingest repeated supratherapeutic amounts of APAP over several weeks may generate APAP-CYS protein adducts in the absence of hepatic injury.

A practical guide to expedition medical planning

Expedition medical planning is integral in ensuring participant safety and maximising the likelihood of achieving the expedition aims. The task of producing a medical plan will often fall to a medical officer of limited experience. The aim of this article is to provide a concise, practical guide to aid junior medical officers (MOs) in forming a robust and pragmatic medical plan.

A phase I study of flavopiridol using an alternative schedule in patients (pts) with advanced solid tumors

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Background: A phase I study of flavopiridol, a cyclin-dependent kinase inhibitor, using an alternative schedule was conducted in pts with solid tumors given its promising activity in pts with chronic lymphocytic leukemia (CLL). Methods: Using standard 3x3 ph I dose escalation design, NCI-sponsored trial was performed to determine the safety and dose-limiting toxicity (DLT) of flavopiridol given as a 30-min IV loading dose followed by a 4-hr infusion weekly for 4 wks repeated every 6 wks. DLT was defined as Gr 4 hematologic toxicity (HT) for > 7 days, > Gr 3 non-HT except Gr 3 fatigue or diarrhea resolving <4 days and cytokine release syndrome (CRS) > Gr 3 despite steroids. Blood samples were obtained at pre-dose and 0.5, 1, 3, 4.5, 6, 8, 24, and 48-hr after start of first bolus dose for pharmacokinetics (PK). Results: 26 pts with advanced solid tumors with a median age of 63 (44–75) yrs were enrolled. Median no. of doses was 7.5 (1–24). Table 1 outlines the PK parameters, DLTs and CRS. Due to a grade 5 CRS/death in cohort 3, the protocol was amended to include 20 mg IV dexamethasone prior to flavopiridol to prevent CRS (cohorts 2B, 1B). Of the 20 evaluable pts, 35% had stable- and 65% had progressive-disease. Results of serum cytokines (IL-2, IL-4, IL-6, TNF-a, IFN-g, IL-10) levels will be presented. Conclusions: There was a higher frequency of CRS, despite prophylactic steroids seen our pts with solid tumors compared to previous studies with CLL and this correlated with AUC. PK and toxicity profile in our pt population differs from pts with hematologic malignancies administered flavopiridol on the same schedule. Protein binding and serum albumin levels are under evaluation as potential contributors. This work is supported by NCI U01-CA76576.

[Table: see text]

[Table: see text]

Sci-Thurs PM: Delivery-05: One year of learning from incidents

The aim of this study is to quantify the effect of an incident learning system in radiation therapy. The system is designed to detect all occurrences of "an unwanted or unexpected change from a normal system behaviour that causes or has the potential to cause an adverse effect to persons or equipment". Our application to radiation therapy defines 5 incident types, four levels of severity and four work domains where errors discovered during routine quality assurance within each domain were not classified as incidents. During 2007, we recorded, corrected, investigated, determined root cause and learned from 657 incidents. The vast majority of these incidents were classified as potential minor clinical incidents having little or no impact on patient treatment. The value of the system lies in the application of the learning portion of the investigation. We demonstrated a dramatic reduction in the rate of more severe incidents by the implementation of several simple tools. Our results also show a reduction of incidents on accelerators treating essentially a single disease site. The only treatment unit treating with both image guidance and intensity modulation recorded the fewest incidents while the cobalt unit with the least technological assistance recorded three times the average treatment unit incidents with a higher severity. Additionally, although the rate of incidents at the point of treatment delivery was low, the impact of those incidents was substantially higher than that of incidents originating during treatment planning. This system has proven to be a powerful program management tool.

Evaluation of cellular dielectric spectroscopy, a whole-cell, label-free technology for drug discovery on Gi-coupled GPCRs

Cellular dielectric spectroscopy (CDS) is an emerging technology capable of detecting a range of whole-cell responses in a label-free manner. A new CDS-based instrument, CellKey, has been developed that is optimized for G-protein coupled receptor (GPCR) detection and has automated liquid handling in microplate format, thereby making CDS accessible to lead generation/optimization drug discovery. In addition to having sufficient throughput, new assay technologies must pass rigorous standards for assay development, signal window, dynamic range, and reproducibility to effectively support drug discovery SAR studies. Here, the authors evaluated CellKey with 3 different G(i)-coupled GPCRs for suitability in supporting SAR studies. Optimized assay conditions compatible with the precision, reproducibility, and throughput required for routine screening were quickly achieved for each target. Across a 1000-fold range in compound potencies, CellKey results correlated with agonist and antagonist data obtained using classical methods ([(35)S]GTPgammaS binding and cAMP production). For partial agonists, relative efficacy measurements also correlated with GTPgammaS data. CellKey detection of positive allosteric modulators appeared superior to GTPgammaS methodology. Agonist and antagonist activity could be accurately quantified under conditions of low receptor expression. CellKey is a new technology platform that uses label-free detection in a homogeneous assay that is unaffected by color quenching and is easily integrated into existing microtiter-based compound testing and data analysis procedures for drug discovery.

Fitting the linear–quadratic model to detailed data sets for different dose ranges

Survival curve behaviour and degree of correspondence between the linear-quadratic (LQ) model and experimental data in an extensive dose range for high dose rates were analysed. Detailed clonogenic assays with irradiation given in 0.5 Gy increments and a total dose range varying from 10.5 to 16 Gy were performed. The cell lines investigated were: CHOAA8 (Chinese hamster fibroblast cells), U373MG (human glioblastoma cells), CP3 and DU145 (human prostate carcinoma cell lines). The analyses were based on chi2-statistics and Monte Carlo simulation of the experiments. A decline of LQ fit quality at very low doses (<2 Gy) is observed. This result can be explained by the hypersensitive effect observed in CHOAA8, U373MG and DU145 data and an adaptive-type response in the CP3 cell line. A clear improvement of the fit is discerned by removing the low dose data points. The fit worsening at high doses also shows that LQ cannot explain this region. This shows that the LQ model fits better the middle dose region of the survival curve. The analysis conducted in our study reveals a dose dependency of the LQ fit in different cell lines.

Left atrial phaeochromocytoma

Phaeochromocytomas of the heart are very rare. This report describes the case of a 69 year old woman presenting with persistent hypertension and a left atrial phaeochromocytoma diagnosed by 131I-metaiodobenzylguanidine scintigraphy scanning. She was successfully treated by surgical excision with the aid of cardiopulmonary bypass and perioperative alpha and beta adrenergic blockade.

Analysis of fentanyl and norfentanyl in human plasma by liquid chromatography-tandem mass spectrometry using electrospray ionization

This report describes a sensitive and specific high-performance liquid chromatography (HPLC)-electrospray ionization-tandem mass spectrometry (MS-MS) method for the detection of subnanogram concentrations of fentanyl and its metabolite norfentanyl in human plasma. The assay was based on a liquid-liquid extraction of 0.5 mL of human plasma, with a lower limit of quantitation (LLOQ) of 0.05 ng/mL. Sample extracts were analyzed using a ThermoQuest TSQ MS-MS interfaced with a Hewlett-Packard series 1100 HPLC and a Phenomenex (30 x 2.00-mm, 5 microLuna C18(2)) column. The intra-assay precision and accuracy ranged from 2.1 to 12.5% for both analytes at concentrations of 0.1, 0.5, 1.0, and 10 ng/mL. The interassay accuracy and precision ranged from 7.34 to 10.95%.

Unsafe sleep practices and an analysis of bedsharing among infants dying suddenly and unexpectedly: results of a four-year, population-based, death-scene investigation study of sudden infant death syndrome and related deaths

BACKGROUND

Prone sleep and unsafe sleep surfaces increase the risk of sudden infant death. Recent epidemiologic studies also suggest that when an infant's head or face is covered by bedding, or when a sleep surface is shared with others, the risk of dying increases. The inference of a causal role for these risk factors is supported by physiologic studies and by the consistent finding that fewer infants die when risk factors are reduced. The prevalence of most of these risk factors in infant deaths in the United States is uncertain.

OBJECTIVE

To describe the prevalence of several important risk factors related to sleep practices among a defined population of infants dying suddenly and unexpectedly.

METHODS

In this population-based study, we retrospectively reviewed death-scene information and medical examiners' investigations of deaths in the city of St Louis and St Louis County between January 1, 1994 and December 31, 1997. Because of the potential for diagnostic overlap, all deaths involving infants <2 years old with the diagnoses of sudden infant death syndrome (SIDS), accidental suffocation, or cause undetermined were included.

RESULTS

The deaths of 119 infants were studied. Their mean age was 109.3 days (range: 6-350). The diagnoses were SIDS in 88 deaths, accidental suffocation in 16, and undetermined in 15. Infants were found prone in 61.1% of cases and were found on a sleep surface not designed for infants in 75.9%. The head or face was covered by bedding in 29.4%. A shared sleep surface was the site of death in 47.1%. Only 8.4% of deaths involved infants found nonprone and alone, with head and face uncovered.

CONCLUSIONS

Using detailed death-scene descriptions, we found that similar unsafe sleeping practices occurred in the large majority of cases diagnosed as SIDS, accidental suffocation, and cause undetermined. Considering these diagnoses together may be useful in public health campaigns during a time when there may be diagnostic overlap. Regardless of the diagnosis, recommendations that infants sleep supine on firm sleep surfaces that lessen the risk of entrapment or head covering have the potential to save many lives. Campaigns are needed to heighten awareness of these messages and of the risks of dangerous bedsharing.

Stay on Your Feet Safety Walks Group

The Safety Walks Group is an initiative that evolved from the Stay on Your Feet Program. The strategies used in this program target both behavioural and environmental change and are based on the five areas for action under the Ottawa Charter (WHO, 1986) and Jakarta Declaration (WHO, 1997). The Safety Walks Group addresses the issue of public hazards via the use of a standard checklist covering pedestrian areas, business houses and accommodation. The project provided a forum for seniors to be proactive, working with the authorities to address the issue of public hazards and make the environment safer.

Failure of autoresuscitation in weanling mice: significance of cardiac glycogen and heart rate regulation

"Autoresuscitation" (AR) is the spontaneous recovery from hypoxic apnea by gasping. We examined aspects of heart function in two situations: 1) the maturationally acquired failure of AR that is characteristic of SWR, but not BALB/c, weanling mice and 2) AR failure in BALB/c mice induced by repeated exposures to anoxia. We determined maturational changes in heart and liver glycogen. Unlike liver glycogen levels, heart glycogen levels in SWR mice differed from those in BALB/c mice. They were consistently much lower throughout maturation and reached a nadir during the brief period when SWR weanling mice are vulnerable to AR failure. Also, rate of cardiac glycogen utilization in vulnerable SWR mice was lower than that of same-aged BALB/c mice and was nil during the latter one-half of the gasping stage when heart function is critical for AR success. Therefore, because glycogen utilization reflects cardiac work, heart failure could explain AR failure in SWR weanlings. Additionally, the increase in hypoxic heart rate that occurs with maturation is developmentally delayed in SWR mice, and this may contribute to their AR failure. Cardiac glycogen was not fully depleted in BALB/c mice during repeated anoxic exposures, indicating other reasons for AR failure. We view these findings as a potential model for the age-related peak in incidence of sudden infant death syndrome.

A dose-controlled study of 153Sm-ethylenediaminetetramethylenephosphonate (EDTMP) in the treatment of patients with painful bone metastases

One hundred and fourteen patients with painful bone metastases participated in this randomised, dose-controlled study of the efficacy and safety of 153Sm-ethylenediaminetetramethylenephosphonate (EDTMP), a systemically administered radiopharmaceutical. Fifty-five patients received single doses of 0.5 mCi/kg and 59 patients received single doses of 1.0 mCi/kg. Treatment with 153-Sm-EDTMP produced improvement from baseline in all patient-rated efficacy assessments, including degree of pain, level of daytime discomfort, quality of sleep and pain relief. During the first 4 weeks after dose administration, when the patients evaluated efficacy daily, there were statistically significant changes from baseline with the 1.0 mCi/kg dose but not with the 0.5 mCi/kg dose. The difference between doses in visual analogue pain scores was statistically significant at week 4 (P = 0.0476). Among subsets of patients examined, female patients with breast cancer receiving 1.0 mCi/kg had the most noticeable improvement. The physicians judged that approximately half of the patients in each dose group were experiencing some degree of pain relief by week 2. This value increased to 55% for the 0.5 mCi/kg group and 70% for the 1.0 mCi/kg group at week 4. More patients in the higher dose group (54%) than in the lower dose group (44%) completed the 16-week study. A predictable level of dose-related marrow suppression was the only toxicity associated with 153Sm-EDTMP treatment. Values for platelets and WBCs reached nadirs at 3 or 4 weeks with both doses and recovered by 8 weeks. Even at their lowest point, the values were generally higher than those associated with infectious or haemorrhagic complications. Myelotoxicity was no greater in female patients than in male patients. Long-term follow-up revealed longer survival among breast cancer patients who had received the higher dose than among those who had received the lower dose. The results suggest that the 1.0 mCi/kg dose of 153Sm-EDTMP is safe and effective for the treatment of painful bone metastases.