Kevin Groen

West Nile virus (WNV) is a mosquito-borne pathogen of global concern that can cause fatal neuroinvasive disease. No specific prophylaxis or treatment exists for WNV or related orthoflavivirus infections, and the determinants of human disease severity remain poorly understood. Here, we report that neutralizing autoantibodies against type I interferons do not impair antiviral antibody development. Among the fully human monoclonal antibodies with potent neutralizing activity against WNV that were discovered, W010 targets a unique epitope within the envelope protein domain III (EDIII) and confers both pre- and post-exposure protection in a murine WNV model, even when interferon signaling is impaired. A second protective antibody, W014, exhibits broad cross-neutralization of other pathogenic orthoflavivirus members, including Japanese encephalitis virus, Murray Valley encephalitis virus, Saint Louis encephalitis virus, and Usutu virus. These findings identify key neutralizing epitopes on WNV EDIII and provide candidates for the development of antibody-based interventions against encephalitic orthoflavivirus infections.

Neutralizing interferon-λ2/3 autoantibodies are identified in 11.8% of individuals with cystic fibrosis, >10-fold the prevalence in controls. Autoantibody-containing plasmas enhance respiratory virus replication in vitro and associate with allergic rhinitis in patients, suggesting that interferon-λ2/3 autoantibodies may impact mucosal pathology.

Autoantibodies neutralizing type I interferons (IFN-Is; IFNα or IFNω) exacerbate severe viral disease, but specific treatments are unavailable. With footprint profiling, we delineate two dominant IFN-I faces commonly recognized by neutralizing IFN-I autoantibody–containing plasmas from aged individuals with HIV-1 and from individuals with severe COVID-19. These faces overlap with IFN-I regions independently essential for engaging the IFNAR1/IFNAR2 heterodimer, and neutralizing plasmas efficiently block the interaction of IFN-I with both receptor subunits in vitro. In contrast, non-neutralizing autoantibody–containing plasmas limit the interaction of IFN-I with only one receptor subunit and display relatively low IFN-I–binding avidities, thus likely hindering neutralizing function. Iterative engineering of signaling-inert mutant IFN-Is (simIFN-Is) retaining dominant autoantibody targets created potent decoys that prevent IFN-I neutralization by autoantibody-containing plasmas and that restore IFN-I–mediated antiviral activity. Additionally, microparticle-coupled simIFN-Is were effective at depleting IFN-I autoantibodies from plasmas, leaving antiviral antibodies unaffected. Our study reveals mechanisms of action for IFN-I autoantibodies and demonstrates a proof-of-concept strategy to alleviate pathogenic effects.

Autoantibodies neutralizing type I interferons (IFN-Is) can underlie infection severity. Here, we trace the development of these autoantibodies at high-resolution using longitudinal samples from 1,876 well-treated individuals living with HIV over a 35-year period. Similar to general populations, ∼1.9% of individuals acquired anti-IFN-I autoantibodies as they aged (median onset ∼63 years). Once detected, anti-IFN-I autoantibodies persisted lifelong, and titers increased over decades. Individuals developed distinct neutralizing and non-neutralizing autoantibody repertoires at discrete times that selectively targeted combinations of IFNα, IFNβ, and IFNω. Emergence of neutralizing anti-IFNα autoantibodies correlated with reduced baseline IFN-stimulated gene levels and was associated with subsequent susceptibility to severe COVID-19 several years later. Retrospective measurements revealed enrichment of pre-existing autoreactivity against other autoantigens in individuals who later developed anti-IFN-I autoantibodies, and there was evidence for prior viral infections or increased IFN at the time of anti-IFN-I autoantibody triggering. These analyses suggest that age-related loss of self-tolerance prior to IFN-I immune-triggering poses a risk of developing lifelong functional IFN-I deficiency.

Interferons (IFNs) are a critical component of innate immune defenses and limit viral disease severity. To advance studies on IFNs and their neutralization by pathogenic autoantibodies, we generated a Renilla luciferase-based reporter cell line capable of detecting the activities of IFN-Is, IFN-II, and IFN-IIIs. The reporter cell line exhibits a 125-to 2000-fold higher sensitivity to IFNs than a commonly-used alternative biological reporter system, and allows for a rapid and simple live-cell workflow for detecting low titer amounts of neutralizing anti-IFN antibodies.

Pre-existing autoantibodies (autoAbs) neutralizing type I interferons (IFN-Is: IFNα, IFNβ, IFNω) have recently been described as significant contributors to the severity of viral infectious diseases. Here, we explore the development and consequences of anti-IFN-I autoAbs at high-resolution using retrospective samples and data from 1876 well-treated individuals >65 years of age enrolled in the Swiss HIV Cohort Study, a nationwide, longitudinal cohort with up to 35 years of follow-up. Approximately 1.9% of individuals developed anti-IFN-I autoAbs, with a median onset age of ∼63 years (range 45-80). Once developed, anti-IFN-I autoAbs persisted for life, and generally increased in titer over years. Most individuals developed distinct neutralizing and non-neutralizing anti-IFN-I autoAb repertoires at discrete times that selectively targeted various combinations of IFNα, IFNβ, and IFNω. Longitudinal analyses further revealed that emergence of neutralizing anti-IFNα autoAbs correlated with reduced IFN-stimulated gene (ISG) levels, indicating impairment of innate immunity. Patient data review suggested that prior recorded viral infections and autoimmune history influence the likelihood of mounting anti-IFN-I autoAbs. Indeed, systematic measurements in biobanked samples revealed significant enrichment of pre-existing autoreactivity against clinically relevant autoantigens in individuals who later developed anti-IFN-I autoAbs. In this context, we describe lifelong neutralizing anti-IFNα autoAbs (and impaired innate immunity), that manifested in an individual following IFNα therapy, and who was retrospectively found to have had pre-existing autoreactivity to β2-glycoprotein-I before IFNα treatment. Our decades-spanning longitudinal analyses illuminate the development and immune implications of anti-IFN-I autoAbs in an aging population, and support a ‘two-hit’ hypothesis whereby loss of self-tolerance prior to immune-triggering with endogenous or exogenous IFN-I may pose a risk for developing late-onset, lifelong IFN-I functional deficiency.