Daily Respiratory Research Analysis
Three impactful respiratory studies stood out today: a population-based investigation shows that most adults with post-COVID-19 syndrome remain symptomatic into the second year without evidence for viral persistence; a virology advance identifies the first permissive cell line (MA104) that supports the full life cycle of human bocavirus 1; and a province-wide cohort links higher short-acting beta-agonist, antibiotic, and oral corticosteroid use to increased mortality and cardiopulmonary events i
Summary
Three impactful respiratory studies stood out today: a population-based investigation shows that most adults with post-COVID-19 syndrome remain symptomatic into the second year without evidence for viral persistence; a virology advance identifies the first permissive cell line (MA104) that supports the full life cycle of human bocavirus 1; and a province-wide cohort links higher short-acting beta-agonist, antibiotic, and oral corticosteroid use to increased mortality and cardiopulmonary events in COPD.
Research Themes
- Long COVID prognosis and pathophysiology
- Respiratory virus mechanistic models enabling therapeutics
- COPD pharmacoepidemiology and risk stratification
Selected Articles
1. MA104 cell line is permissive for human bocavirus 1 infection.
Screening across 36 human/animal cell lines identified MA104 as the first permissive cell line that supports full HBoV1 entry, replication, and production of infectious progeny. Interferon pathway suppression enhanced replication, and transcriptomics implicated innate immune and membrane-related pathways.
Impact: This is the first cell system enabling full HBoV1 culture, unlocking mechanistic studies and antiviral/vaccine development for a clinically relevant respiratory pathogen.
Clinical Implications: While not immediately changing bedside care, a permissive cell line will accelerate development and testing of diagnostics, antivirals, and vaccines for HBoV1-related respiratory disease.
Key Findings
- Among 29 human and 7 animal cell lines, MA104 uniquely supported the complete HBoV1 life cycle (entry, replication, infectious progeny).
- Suppressing the interferon pathway facilitated HBoV1 genome replication in MA104 cells.
- RNA-seq revealed activation of innate immunity, inflammatory responses, PI3K-Akt/MAPK signaling, and membrane system remodeling upon infection.
Methodological Strengths
- Systematic screening across a broad panel of 36 cell lines with clear replication readouts.
- Orthogonal validation including infectious progeny production and transcriptomic profiling.
Limitations
- Findings are in vitro; no in vivo validation of pathogenesis.
- MA104 is a non-human (monkey kidney-derived) line, which may limit direct translation to human airway epithelium.
Future Directions: Leverage MA104 for high-throughput antiviral screening and vaccine studies; define receptors and entry cofactors; develop human airway organoid models to corroborate findings.
Human bocavirus 1 (HBoV1) has appeared as an emerging pathogen, causing mild to life-threatening respiratory tract infections, acute otitis media, and encephalitis in young children and immunocompromised individuals. The lack of cell lines suitable for culturing replicative viruses hinders research on HBoV1. Here, we characterized the susceptibility to HBoV1 of 29 human and 7 animal cell lines, and identified a permissive cell line, MA104. The complete HBoV1 life cycle was achieved in MA104 cells, including viral entry, complete replication, and infectious progeny virion production. Additionally, the suppression of the interferon pathway facilitated the viral genome replication in MA104 cells. RNA-sequencing showed that innate immunity, inflammation, the PI3K-Akt and MAPK signaling pathways, and the cellular membrane system were mobilized in response to HBoV1 infection. Overall, our study is the first to identify a cell line, MA104, that supports the complete HBoV1 life cycle, which will promote research on HBoV1 virology and pathogenesis and benefit drug and vaccine development.IMPORTANCEHBoV1 is an emerging pathogen that mainly causes respiratory tract infections, while the lack of cell lines suitable for culture replicative viruses hindered research on HBoV1. Here, we identify a permissive cell line for HBoV1 infection, MA104, and reveal that the complete life cycle of HBoV1 was supported in MA104 cells.
2. Persistent symptoms and clinical findings in adults with post-acute sequelae of COVID-19/post-COVID-19 syndrome in the second year after acute infection: A population-based, nested case-control study.
In a nested population-based study (982 PCS, 576 controls), 67.6% of adults with PCS remained symptomatic into the second year. Objective deficits included reduced handgrip strength, lower peak VO2 (27.9 vs 31.0 ml/min/kg), and higher VE/VCO2 slope. No evidence supported viral persistence, EBV reactivation, adrenal insufficiency, or elevated complement as drivers; post-exertional malaise identified a more severe phenotype.
Impact: Provides high-quality, population-based evidence on long-term PCS trajectories with comprehensive objective testing and refutes several hypothesized biological drivers.
Clinical Implications: Emphasizes rehabilitation and symptom-targeted care (e.g., pacing for post-exertional malaise), risk-factor modification (obesity, smoking), and deprioritizes antiviral or endocrine testing in persistent PCS absent specific indications.
Key Findings
- 67.6% of PCS cases remained symptomatic >1 year; predominant clusters were fatigue, cognitive issues, breathlessness, and sleep/anxiety.
- Objective impairments vs recovered controls: lower handgrip strength (40.2 vs 42.5 kg), reduced peak VO2 (27.9 vs 31.0 ml/min/kg), and higher VE/VCO2 slope (28.8 vs 27.1).
- No biomarker evidence for viral persistence (stool PCR, plasma spike antigen negative), EBV reactivation, adrenal insufficiency, or increased complement turnover.
- Post-exertional malaise associated with more severe symptoms and broader objective deficits.
Methodological Strengths
- Population-based nested design with large sample and matched controls plus comprehensive, standardized testing across domains.
- Adjusted analyses for demographics, center, education, BMI, smoking, and beta-blocker use.
Limitations
- No pre-infection baseline for cognition/exercise capacity; changes inferred relative to controls.
- Clinic-based reassessment excluded individuals unable to attend (potential selection bias).
Future Directions: Define longitudinal phenotypes and response to targeted rehabilitation; test pacing strategies in PEM-positive PCS; mechanistic work on dysautonomia and ventilatory inefficiency.
BACKGROUND: Self-reported health problems following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are common and often include relatively non-specific complaints such as fatigue, exertional dyspnoea, concentration or memory disturbance and sleep problems. The long-term prognosis of such post-acute sequelae of COVID-19/post-COVID-19 syndrome (PCS) is unknown, and data finding and correlating organ dysfunction and pathology with self-reported symptoms in patients with non-recovery from PCS is scarce. We wanted to describe clinical characteristics and diagnostic findings among patients with PCS persisting for >1 year and assessed risk factors for PCS persistence versus improvement. METHODS AND FINDINGS: This nested population-based case-control study included subjects with PCS aged 18-65 years with (n = 982) and age- and sex-matched control subjects without PCS (n = 576) according to an earlier population-based questionnaire study (6-12 months after acute infection, phase 1) consenting to provide follow-up information and to undergo comprehensive outpatient assessment, including neurocognitive, cardiopulmonary exercise, and laboratory testing in four university health centres in southwestern Germany (phase 2, another 8.5 months [median, range 3-14 months] after phase 1). The mean age of the participants was 48 years, and 65% were female. At phase 2, 67.6% of the patients with PCS at phase 1 developed persistent PCS, whereas 78.5% of the recovered participants remained free of health problems related to PCS. Improvement among patients with earlier PCS was associated with mild acute index infection, previous full-time employment, educational status, and no specialist consultation and not attending a rehabilitation programme. The development of new symptoms related to PCS among participants initially recovered was associated with an intercurrent secondary SARS-CoV-2 infection and educational status. Patients with persistent PCS were less frequently never smokers (61.2% versus 75.7%), more often obese (30.2% versus 12.4%) with higher mean values for body mass index (BMI) and body fat, and had lower educational status (university entrance qualification 38.7% versus 61.5%) than participants with continued recovery. Fatigue/exhaustion, neurocognitive disturbance, chest symptoms/breathlessness and anxiety/depression/sleep problems remained the predominant symptom clusters. Exercise intolerance with post-exertional malaise (PEM) for >14 h and symptoms compatible with myalgic encephalomyelitis/chronic fatigue syndrome were reported by 35.6% and 11.6% of participants with persistent PCS patients, respectively. In analyses adjusted for sex-age class combinations, study centre and university entrance qualification, significant differences between participants with persistent PCS versus those with continued recovery were observed for performance in three different neurocognitive tests, scores for perceived stress, subjective cognitive disturbances, dysautonomia, depression and anxiety, sleep quality, fatigue and quality of life. In persistent PCS, handgrip strength (40.2 [95% confidence interval (CI) [39.4, 41.1]] versus 42.5 [95% CI [41.5, 43.6]] kg), maximal oxygen consumption (27.9 [95% CI [27.3, 28.4]] versus 31.0 [95% CI [30.3, 31.6]] ml/min/kg body weight) and ventilatory efficiency (minute ventilation/carbon dioxide production slope, 28.8 [95% CI [28.3, 29.2]] versus 27.1 [95% CI [26.6, 27.7]]) were significantly reduced relative to the control group of participants with continued recovery after adjustment for sex-age class combinations, study centre, education, BMI, smoking status and use of beta...
3. Short-acting beta agonist, antibiotics, oral corticosteroid and association with mortality and cardiopulmonary events in patients with COPD: a retrospective cohort study in Alberta, Canada.
In 188,969 COPD patients followed in 90-day intervals, higher SABA, antibiotic, and OCS use was associated with increased mortality in dose–response fashion. ≥6 SABA dispenses vs 1 was linked to higher all-cause (HR 1.20) and COPD mortality (HR 1.40). Frequent antibiotics and OCS bursts were also associated with higher mortality; 2–5 SABA dispenses increased post-exacerbation MACE and CVD death.
Impact: Identifies real-world medication-use patterns as strong prognostic markers in COPD, informing stewardship and highlighting risks of reliever reliance and frequent rescue therapies.
Clinical Implications: Prioritize optimization of maintenance therapy to reduce SABA reliance; implement antibiotic/OCS stewardship and close follow-up for high-use patients; consider SABA dispensing frequency as a risk stratifier for mortality and MACE.
Key Findings
- Dose–response relationship: ≥6 SABA dispenses vs 1 associated with higher all-cause mortality (HR 1.20) and COPD mortality (HR 1.40).
- ≥6 antibiotic dispenses associated with 62% higher all-cause mortality and 43% higher COPD mortality; ≥6 OCS burst-days associated with ~27–29% higher mortality.
- 2–5 SABA dispenses associated with increased post-exacerbation MACE and cardiovascular death at the site level.
Methodological Strengths
- Very large administrative cohort with time-varying exposure windows over 9 years.
- Adjusted for comorbidities and demographics; multiple outcomes (mortality, MACE) assessed.
Limitations
- Observational design subject to confounding by indication and residual confounding.
- Dispensing data proxy actual medication use; disease severity measures (e.g., spirometry) not uniformly available.
Future Directions: Prospective interventions to reduce SABA/antibiotic/OCS overuse and test impact on mortality/MACE; external validation in other health systems; integrate spirometry and exacerbation severity.
OBJECTIVE: The purpose of the study was to examine the association between short-acting beta agonist (SABA), antibiotic and oral corticosteroid (OCS) use and mortality and cardiopulmonary outcomes in chronic obstructive pulmonary disease (COPD). DESIGN: Retrospective cohort study using administrative health data from 1 April 2011 to 31 March 2020. SETTING: Alberta, Canada. PARTICIPANTS: Patients ≥35 years old with COPD were identified using diagnostic codes. PRIMARY AND SECONDARY OUTCOME MEASURES: Patient characteristics included age, sex, geographical zone and comorbidities (as defined by the Charlson Comorbidity Index). Outcome variables included all-cause and COPD-related mortality. Outcomes were assessed in consecutive 90-day intervals, starting from cohort entry, paired with time-varying COPD-related medication history in the 1 year preceding each interval. Associations were modelled between mortality and SABA, antibiotic and OCS history, and between major adverse cardiac events (MACE) and cardiovascular disease (CVD) death and SABA history. RESULTS: Among 188 969 patients, dose-response effects were observed...