Development and validation of a respiratory syncytial virus multiplex immunoassay.

PURPOSE: Respiratory syncytial virus (RSV) is one of the leading causes of severe respiratory disease in infants and adults. While vaccines and monoclonal therapeutic antibodies either are or will shortly become available, correlates of protection remain unclear. For this purpose, we developed an RSV multiplex immunoassay that analyses antibody titers toward the post-F, Nucleoprotein, and a diverse mix of G proteins. METHODS: A bead-based multiplex RSV immunoassay was developed, technically validated to standard FDA bioanalytical guidelines, and clinically validated using samples from human challenge studies. RSV antibody titers were then investigated in children aged under 2 and a population-based cohort. RESULTS: Technical and clinical validation showed outstanding performance, while methodological developments enabled identification of the subtype of previous infections through use of the diverse G proteins for approximately 50% of samples. As a proof of concept to show the suitability of the assay in serosurveillance studies, we then evaluated titer decay and age-dependent antibody responses within population cohorts. CONCLUSION: Overall, the developed assay shows robust performance, is scalable, provides additional information on infection subtype, and is therefore ideally suited to be used in future population cohort studies.

Wearable Sensor-Based Detection of Influenza in Presymptomatic and Asymptomatic Individuals.

BACKGROUND: The COVID-19 pandemic highlighted the need for early detection of viral infections in symptomatic and asymptomatic individuals to allow for timely clinical management and public health interventions. METHODS: Twenty healthy adults were challenged with an influenza A (H3N2) virus and prospectively monitored from 7 days before through 10 days after inoculation, using wearable electrocardiogram and physical activity sensors. This framework allowed for responses to be accurately referenced to the infection event. For each participant, we trained a semisupervised multivariable anomaly detection model on data acquired before inoculation and used it to classify the postinoculation dataset. RESULTS: Inoculation with this challenge virus was well-tolerated with an infection rate of 85%. With the model classification threshold set so that no alarms were recorded in the 170 healthy days recorded, the algorithm correctly identified 16 of 17 (94%) positive presymptomatic and asymptomatic individuals, on average 58 hours postinoculation and 23 hours before the symptom onset. CONCLUSIONS: The data processing and modeling methodology show promise for the early detection of respiratory illness. The detection algorithm is compatible with data collected from smartwatches using optical techniques but needs to be validated in large heterogeneous cohorts in normal living conditions. Clinical Trials Registration. NCT04204493.

Divergent age-related humoral correlates of protection against respiratory syncytial virus infection in older and young adults: a pilot, controlled, human infection challenge model.

BACKGROUND: Respiratory viral infections are typically more severe in older adults. Older adults are more vulnerable to infection and do not respond effectively to vaccines due to a combination of immunosenescence, so-called inflamm-ageing, and accumulation of comorbidities. Although age-related changes in immune responses have been described, the causes of this enhanced respiratory disease in older adults remain poorly understood. We therefore performed volunteer challenge with respiratory syncytial virus (RSV) in groups of younger and older adult volunteers. The aim of this study was to establish the safety and tolerability of this model and define age-related clinical, virological, and immunological outcomes. METHODS: In this human infection challenge pilot study, adults aged 18-55 years and 60-75 years were assessed for enrolment using protocol-defined inclusion and exclusion criteria. Symptoms were documented by self-completed diaries and viral load determined by quantitative PCR of nasal lavage. Peripheral blood B cell frequencies were measured by enzyme-linked immunospot and antibodies against pre-fusion and post-fusion, NP, and G proteins in the blood and upper respiratory tract were measured. The study was registered with ClinicalTrials.gov, NCT03728413. FINDINGS: 381 adults aged 60-75 years (older cohort) and 19 adults aged 18-55 years (young cohort) were assessed for enrolment using protocol-defined inclusion and exclusion criteria between Nov 12, 2018, and Feb 26, 2020. 12 healthy volunteers aged 60-75 years and 21 aged 18-55 years were inoculated intranasally with RSV Memphis-37. Nine (67%) of the 12 older volunteers became infected, developing mild-to-moderate upper respiratory tract symptoms that resolved without serious adverse events or sequelae. Viral load peaked on day 6 post-inoculation and symptoms peaked between days 6 and 8. Increases in circulating IgG-positive and IgA-positive antigen-specific plasmablasts, serum neutralising antibodies, and pre-F specific IgG were similar younger and older adults. However, in contrast to young participants, secretory IgA titres in older volunteers failed to increase during infection and, unlike serum IgG, did not correlate with protection. INTERPRETATION: Better understanding of age-related differences in clinical outcomes and immune correlates of protection can overcome reduction in vaccine efficacy with advancing age. We identify correlates of protection in older adults, revealing previously unrecognised factors which might have implications for targeted vaccine discovery and drug development in this vulnerable group. FUNDING: Medical Research Council and GlaxoSmithKline EMINENT Consortium.

Controlled Human Infection Challenge Studies with RSV.

Despite considerable momentum in the development of RSV vaccines and therapeutics, there remain substantial barriers to the development and licensing of effective agents, particularly in high-risk populations. The unique immunobiology of RSV and lack of clear protective immunological correlates has held back RSV vaccine development, which, therefore, depends on large and costly clinical trials to demonstrate efficacy. Studies involving the deliberate infection of human volunteers offer an intermediate step between pre-clinical and large-scale studies of natural infection. Human challenge has been used to demonstrate the potential efficacy of vaccines and antivirals while improving our understanding of the protective immunity against RSV infection. Early RSV human infection challenge studies determined the role of routes of administration and size of inoculum on the disease. However, inherent limitations, the use of highly attenuated/laboratory-adapted RSV strains and the continued evolutionary adaptation of RSV limits extrapolation of results to present-day vaccine testing. With advances in technology, it is now possible to perform more detailed investigations of human mucosal immunity against RSV in experimentally infected adults and, more recently, older adults to optimise the design of vaccines and novel therapies. These studies identified defects in RSV-induced humoral and CD8+ T cell immunity that may partly explain susceptibility to recurrent RSV infection. We discuss the insights from human infection challenge models, ethical and logistical considerations, potential benefits, and role in streamlining and accelerating novel antivirals and vaccines against RSV. Finally, we consider how human challenges might be extended to include relevant at-risk populations.

A Review of Mixed Strain Clostridium difficile Colonization and Infection.

Given that Clostridium difficile is not part of the normal human microbiota, if multiple strains are to accumulate in the colon implies successive exposure events and/or persistent colonization must occur. Evidence of C. difficile infection (CDI) with more than one strain was first described in 1983. Despite the availability of increasingly discriminatory bacterial fingerprinting methods, the described rate of dual strain recovery in patients with CDI has remained stable at ∼5-10%. More data are needed to determine when dual strain infection may be harmful. Notably, one strain may block the establishment of and infection by another. In humans, patients colonized by non-toxigenic C. difficile strain are at a lower risk of developing CDI. Further studies to elucidate the interaction between co-infecting or colonizing and infecting C. difficile strains may help identify potential exploitable mechanisms to prevent CDI.

Irritable bowel syndrome following Clostridium difficile infection.

PURPOSE OF REVIEW: The aim of this review was to provide an overview of the current understanding of the diagnosis, pathophysiology, and the role of the gut microbiome in Clostridium difficile infection (CDI)-related postinfectious irritable bowel syndrome (PI-IBS). RECENT FINDINGS: PI-IBS is a recognized pathological entity and was estimated to affect 1 in 10 patients with infectious enteritis. CDI remains a major healthcare burden worldwide with a one in four chance of recurrence of symptoms following treatment. While there is growing interest in functional gastrointestinal disorders including PI-IBS, studies examining the prevalence and risk factors of CDI-related PI-IBS remain scarce. One of many proposed mechanisms for PI-IBS is related to dysbiosis of the gut microbiota, which is the hallmark of CDI pathogenesis. Therefore, restoration of the gut microbiota, which is associated with successful outcomes in CDI, may be a potential treatment option for PI-IBS. However, two randomized controlled trails exploring the restoration of the gut microbiota using faecal microbiota transplant came to differing conclusions. SUMMARY: PI-IBS, particularly CDI-related PI-IBS, remains an understudied area. A better understanding of the pathophysiology of PI-IBS is essential to developing more specific and effective management strategies.

Are patients with newly diagnosed breast cancer getting appropriate DEXA scans? A District General Hospital experience.

Breast cancer patients are often at high risk of fragility fractures partly due to adjuvant endocrine therapy such as aromatase inhibitors and chemotherapy. Baseline dual energy X-ray absorptiometry (DEXA) scanning is recommended as a standard of care in identifying patients who are at risk so they can be commenced on bone protective therapy. NICE guideline 80 - "Early and locally advanced breast cancer"[1] states that patients with early invasive breast cancer should have a baseline DEXA scan to assess BMD before the commencement of aromatase inhibitor treatment; if patients have treatment-induced menopause or are starting ovarian ablation/suppression therapy. We have audited the performance of a DGH against these guidelines with a target of 100% concordance. During a one year period (April 2012-April 2013), 100 patients with a new diagnosis of breast cancer were selected at random from the hospital coding database. 100 patients were chosen as this was a convenient sample size. We gathered information for these patients using electronic records, letters, and imaging. This showed a poor compliance of 38% against NICE guidelines. This in turn means that patients with low BMD at diagnosis of breast cancer are being under diagnosed and under treated, resulting in increased potential morbidity associated with fragility fractures. The interventions that resulted from this audit were: dissemination of these results to surgical and oncology departments, posters summarising the guidelines put up in breast clinics, and breast MDTs to discuss the need for DEXA scans for patients with breast cancer. A re-audit was performed for patients diagnosed with early, invasive breast cancer in January 2014 where a compliance of 90% was achieved. This represents a huge improvement in compliance from the baseline measure of 38%. In order to show that this improvement could be sustained, two further cycles were performed in February and March 2014, where the compliance was 92% and 100% respectively. Therefore the improvement in compliance was not only maintained but in fact the compliance increased even further during subsequent cycles. Hence we have achieved a large improvement in the quality of assessment of bone quality in breast cancer patients. Moreover, we have demonstrated the importance of the dissemination of information and education within a multidisciplinary setting.