Daily Respiratory Research Analysis
Top respiratory research today spans mechanistic virology and population-scale prevention. A PLoS Pathogens study reveals a mitochondrial localization signal in measles nucleoprotein that targets replication factories near mitochondria, reshaping our understanding of airway infection. Translational advances include AI- and glyco-engineered interferon-λ for intranasal prophylaxis, and real-world evidence that nirsevimab sharply reduces infant RSV hospitalizations and severity.
Summary
Top respiratory research today spans mechanistic virology and population-scale prevention. A PLoS Pathogens study reveals a mitochondrial localization signal in measles nucleoprotein that targets replication factories near mitochondria, reshaping our understanding of airway infection. Translational advances include AI- and glyco-engineered interferon-λ for intranasal prophylaxis, and real-world evidence that nirsevimab sharply reduces infant RSV hospitalizations and severity.
Research Themes
- Virus–host organelle interactions in respiratory epithelium
- Engineered mucosal biologics for respiratory virus prophylaxis
- Population-level effectiveness of RSV immunoprophylaxis
Selected Articles
1. Mitochondrial targeting by measles virus nucleoprotein modulates viral spread in human airway epithelium.
Using primary human airway epithelium, the authors identify a previously unrecognized mitochondrial localization signal within the measles nucleoprotein that targets replication complexes near mitochondria. Mutating key arginines disrupts targeting and alters replication kinetics and infectious center formation without changing ISG profiles, revealing organelle-level viral–host coordination.
Impact: This work uncovers a unique organelle-targeting mechanism in a major respiratory pathogen, opening avenues for antivirals that disrupt mitochondrial-proximal replication. It reframes measles pathogenesis in airway epithelium with direct translational relevance for intervention strategies.
Clinical Implications: While preclinical, targeting the N-protein mitochondrial localization or disrupting replication factory proximity could inspire antiviral development. It also suggests that innate sensing modulation in airway epithelium may be leveraged for disease control.
Key Findings
- Measles virus replication disrupts mitochondrial membrane potential and increases superoxide, inducing cGAS-dependent ISG expression without interferon induction.
- MeV proteins/genome are enriched in mitochondrial fractions; the N protein contains an N-terminal mitochondrial localization signal sufficient to target GFP to mitochondria.
- Arginine 6 and 13 in N are critical for targeting; MLS mutations alter replication kinetics and infectious center formation in human airway epithelium.
Methodological Strengths
- Use of well-differentiated primary human airway epithelial cells recapitulating in vivo infection biology
- Convergent mechanistic approaches: mitochondrial fractionation, functional mitochondrial assays, mutational mapping, and recombinant virus phenotyping
Limitations
- Lack of in vivo validation to confirm mitochondrial targeting in whole-animal infection
- Clinical correlations and therapeutic targeting of the MLS were not tested
Future Directions: Validate MLS-dependent mitochondrial targeting in vivo, define structural determinants for inhibitor design, and test small molecules/peptides that disrupt N–mitochondria interactions in airway models.
Measles is the most infectious human respiratory virus: on average, one individual with measles infects 12-18 susceptible people in a population without immunity. However, how measles virus (MeV) establishes infection in the human respiratory epithelium is insufficiently understood. Since our analyses of MeV infections of well-differentiated primary human airway epithelial cells (HAE) revealed perturbations of mitochondrial gene expression, we tested mitochondrial function. MeV replication disrupted mitochondrial membrane potential and induced superoxide production. This resulted in cGAS-dependent interferon-stimulated gene expression without interferon induction. We then assessed by differential centrifugation whether MeV replicates in mitochondrial proximity. Indeed, MeV proteins and genome were enriched in mitochondrial fractions. We identified a previously unrecognized potential mitochondrial localization signal (MLS) in the MeV nucleoprotein (N), the first protein expressed during infection and showed that the first 70 amino acids of N are sufficient to deliver a GFP reporter to mitochondria. Mutational analyses revealed that arginine 6 and arginine 13 of the N protein are critical for targeting. Recombinant MeV mutants harboring single MLS amino acid substitutions exhibited altered replication kinetics and infectious center formation in HAE, despite similar ISG expression profiles to wild-type MeV. Thus, the MeV N protein amino-terminal arm, previously known only to promote formation of the helical ribonucleocapsid protecting the viral genome, also codes for an MLS. In newly infected cells, this signal may target the formation of MeV replication factories near mitochondria without provoking a canonical RNA sensing pathway. Notably, the MLS appears unique to Morbillivirus N proteins within the Paramyxoviridae family, which are also distinguished by the unique ability to form infectious centers in HAE. Our findings reveal a novel mechanism by which MeV exploits mitochondrial proximity to coordinate replication and modulate host responses, offering new insights into virus-host interactions at the organelle level.
2. Computational Design and Glycoengineering of Interferon-Lambda for Nasal Prophylaxis Against Respiratory Viruses.
AI-guided backbone remodeling and targeted glyco-engineering generated a hyperstable, protease-resistant IFN-λ3 variant with improved mucus diffusion and rapid intranasal prophylaxis against influenza A in vivo. This modular strategy preserves antiviral potency while enabling manufacturability and mucosal bioavailability.
Impact: Provides a blueprint for engineering durable mucosal biologics targeting epithelial cells, with direct implications for broad-spectrum respiratory virus prophylaxis. The combination of AI design and glycoengineering is a notable methodological advance.
Clinical Implications: If translated to humans, intranasal engineered IFN-λ could offer pre-/post-exposure prophylaxis with improved stability and delivery, complementing vaccines and monoclonals during seasonal surges or emergent outbreaks.
Key Findings
- AI-based backbone remodeling and hydrophobic patch engineering produced IFN-λ3-DE1 with Tm > 90°C, protease resistance, and preserved antiviral activity under heat stress.
- Addition of an N-linked glycan improved solubility, yield, and diffusion through synthetic nasal mucus without compromising receptor binding interfaces.
- Intranasal G-hIFN-λ3-DE1 achieved effective mucosal penetration and a faster onset of in vivo prophylaxis against influenza A.
Methodological Strengths
- Integrated computational protein design with experimental validation of stability, protease resistance, and activity
- Demonstration of mucus diffusion and in vivo prophylactic efficacy following intranasal delivery
Limitations
- Preclinical models; human pharmacokinetics, safety, and dosing remain to be established
- Efficacy shown against influenza A; breadth against other respiratory viruses requires testing
Future Directions: Advance to phase 1 intranasal studies, map cytokine and epithelial responses in human nasal mucosa, and evaluate spectrum against RSV, parainfluenza, and coronaviruses.
Interferon-λ (IFN-λ), a type III interferon that selectively targets epithelial cells, holds strong potential as an intranasal antiviral due to its ability to suppress respiratory virus replication without inducing systemic inflammation. However, clinical translation of human IFN-λ3 (hIFN-λ3) is hindered by limited thermostability, protease susceptibility, and rapid mucosal clearance. In this study, instability-prone elements in hIFN-λ3 are eliminated through artificial intelligence (AI)-based backbone remodeling and targeted surface hydrophobic patch engineering. A protease-sensitive loop is replaced with a de novo α-helix, which shields neighboring hydrophobic patches and forms a new hydrophobic core, yielding an engineered variant (hIFN-λ3-DE1) with enhanced thermostability (Tm > 90 °C), protease resistance, and preserved antiviral activity and structural integrity even after extended heat stress (two weeks at 50 °C). Further glyco-engineering introduces an N-linked glycan at a site distant from receptor-binding interfaces, improving solubility, production yield, and diffusion through synthetic nasal mucus. Intranasal administration of the resulting variant (G-hIFN-λ3-DE1) enables effective mucosal penetration and provides a more rapid onset of in vivo prophylactic protection against influenza A virus. These findings highlight a robust and versatile strategy that combines AI-driven structural design with glyco-engineering to develop scalable, bioavailable, and functionally enhanced nasal biologics for respiratory virus prophylaxis.
3. Nirsevimab Prophylaxis and Respiratory Syncytial Virus Hospitalizations Among Infants.
In 13,624 infants across 5 centers, universal nirsevimab coverage (~79%) was associated with a 68% lower RSV hospitalization hazard (HR 0.32) and reduced HFNC use among hospitalized infants. Prematurity and living with older siblings remained strong risk factors despite prophylaxis.
Impact: Provides robust multicenter real-world evidence supporting universal infant nirsevimab as a public health strategy, while delineating residual high-risk groups requiring complementary measures.
Clinical Implications: Supports birthing-hospital administration and high coverage campaigns. Clinicians should prioritize outreach and supplemental strategies (eg, maternal vaccination, household hygiene) for preterm infants and those with older siblings.
Key Findings
- Population-level reduction in RSV hospitalization hazard after universal nirsevimab (HR 0.32; 95% CI 0.25–0.44).
- Within-month analysis showed strong individual-level protection (HR 0.11; 95% CI 0.06–0.21).
- Among hospitalized infants, HFNC use decreased (OR 0.33), but length of stay was unchanged; prematurity and older siblings remained key risk factors.
Methodological Strengths
- Large multicenter cohort with hierarchical Cox models adjusting for seasonality and center effects
- Sensitivity analyses including within-month comparisons and non-RSV LRTI controls
Limitations
- Observational before–after design susceptible to residual confounding and secular trends
- No significant reduction in length of stay; outpatient impacts not assessed
Future Directions: Evaluate cost-effectiveness, equity of access, and combined strategies (maternal vaccination plus infant prophylaxis); assess indirect effects on non-RSV LRTIs and health system burden.
IMPORTANCE: Respiratory syncytial virus (RSV) is the leading cause of infant hospitalizations, and preterm infants and those with older siblings are at increased risk. Despite recommendations for nirsevimab prophylaxis, data on outcomes in high-risk infants are lacking. OBJECTIVE: To assess the association of nirsevimab prophylaxis with RSV-related lower respiratory tract infection (LRTI) hospitalization risk and in-hospital severity among infants, overall and by high-risk groups. DESIGN, SETTING, AND PARTICIPANTS: This retrospective multicenter cohort study comparing RSV seasons before (April 1, 2023, to March 31, 2024) and after (April 1, 2024, to March 31, 2025) universal nirsevimab prophylaxis implementation included all live births from 5 neonatal hospitals serving the Italian provinces of Ravenna, Faenza, Forlì, Cesena, and Rimini with no exclusions based on gestational age or comorbidities. Participants were followed up from hospital discharge until first RSV hospitalization, first birthday, or season end, with time-to-event analysis. Data from centralized electronic medical records included demographics, nirsevimab administration, and polymerase chain reaction-confirmed RSV. EXPOSURE: Nirsevimab prophylaxis vs no prophylaxis. MAIN OUTCOMES AND MEASURES: The primary outcome was RSV-associated hospitalization in the first year of life. The secondary outcome was LRTI severity measures-hospital length of stay, high-flow nasal cannula (HFNC) use, and intensive care unit (ICU) admission. Hierarchical Cox proportional hazards regression models (with health care center as a random effect) were used to adjust for seasonality and relevant covariates, with sensitivity analyses using multiple models and non-RSV LRTI comparisons. RESULTS: Among 13 624 newborns (mean [SD] gestational age of 39.4 [1.8] weeks; 51.4% male, 4.8% preterm, and 49.5% with older siblings), nirsevimab prophylaxis achieved 79.2% coverage of the study population. Among 292 infants hospitalized with RSV LRTI (2.1%), fewer were in the postnirsevimab than prenirsevimab season group (72 [24.7%] vs 220 [75.3%]; P < .001), with a population-level reduction in hospitalization hazard (hazard ratio [HR], 0.32; 95% CI, 0.25-0.44; P < .001). In a separate within-month analysis comparing infants born in the same calendar month and therefore at similar baseline RSV risk, nirsevimab prophylaxis was associated with a lower hazard of RSV hospitalization (HR, 0.11; 95% CI, 0.06-0.21; P < .001). Prematurity (HR, 2.93; 95% CI, 2.11-4.07; P < .001) and living with older siblings (HR, 4.57; 95% CI, 4.15-5.03; P < .001) remained associated with higher hospitalization risk among infants who received prophylaxis. Among hospitalized infants, nirsevimab was associated with reduced HFNC use (OR, 0.33; 95% CI, 0.11-0.97; P = .04) but not with shorter stays (incidence rate ratio, 0.81; 95% CI, 0.63-1.03; P = .09). CONCLUSIONS AND RELEVANCE: In this multicenter cohort study, nirsevimab prophylaxis was associated with substantially lower RSV hospitalization risk and reduced in-hospital RSV severity, supporting its implementation as a public health strategy. However, the persistent risk associated with prematurity and household RSV exposure suggests a need for supplemental approaches to optimize RSV prevention in high-risk infants.