Cytokine Activation by Antibody Fragments Targeted to Cytokine-Receptor Signaling Complexes.

Exogenous cytokine therapy can induce systemic toxicity, which might be prevented by activating endogenously produced cytokines in local cell niches. Here we developed antibody-based activators of cytokine signaling (AcCS), which recognize cytokines only when they are bound to their cell surface receptors. AcCS were developed for type I interferons (IFNs), which induce cellular activities by binding to cell surface receptors IFNAR1 and IFNAR2. As a potential alternative to exogenous IFN therapy, AcCS were shown to potentiate the biological activities of natural IFNs by ∼100-fold. Biochemical and structural characterization demonstrates that the AcCS stabilize the IFN-IFNAR2 binary complex by recognizing an IFN-induced conformational change in IFNAR2. Using IFN mutants that disrupt IFNAR1 binding, AcCS were able to enhance IFN antiviral potency without activating antiproliferative responses. This suggests AcCS can be used to manipulate cytokine signaling for basic science and possibly for therapeutic applications.

Soft-X-ray-enhanced electrostatic precipitation for protection against inhalable allergens, ultrafine particles, and microbial infections.

Protection of the human lung from infectious agents, allergens, and ultrafine particles is difficult with current technologies. High-efficiency particulate air (HEPA) filters remove airborne particles of >0.3 µm with 99.97% efficiency, but they are expensive to maintain. Electrostatic precipitation has been used as an inexpensive approach to remove large particles from airflows, but it has a collection efficiency minimum in the submicrometer size range, allowing for a penetration window for some allergens and ultrafine particles. Incorporating soft X-ray irradiation as an in situ component of the electrostatic precipitation process greatly improves capture efficiency of ultrafine particles. Here we demonstrate the removal and inactivation capabilities of soft-X-ray-enhanced electrostatic precipitation technology targeting infectious agents (Bacillus anthracis, Mycobacterium bovis BCG, and poxviruses), allergens, and ultrafine particles. Incorporation of in situ soft X-ray irradiation at low-intensity corona conditions resulted in (i) 2-fold to 9-fold increase in capture efficiency of 200- to 600-nm particles and (ii) a considerable delay in the mean day of death as well as lower overall mortality rates in ectromelia virus (ECTV) cohorts. At the high-intensity corona conditions, nearly complete protection from viral and bacterial respiratory infection was afforded to the murine models for all biological agents tested. When optimized for combined efficient particle removal with limited ozone production, this technology could be incorporated into stand-alone indoor air cleaners or scaled for installation in aircraft cabin, office, and residential heating, ventilating, and air-conditioning (HVAC) systems.

Structure and mechanism of IFN-gamma antagonism by an orthopoxvirus IFN-gamma-binding protein.

Ectromelia virus (ECTV) encodes an IFN-gamma-binding protein (IFN-gammaBP(ECTV)) that disrupts IFN-gamma signaling and its ability to induce an antiviral state within cells. IFN-gammaBP(ECTV) is an important virulence factor that is highly conserved (>90%) in all orthopoxviruses, including variola virus, the causative agent of smallpox. The 2.2-A crystal structure of the IFN-gammaBP(ECTV)/IFN-gamma complex reveals IFN-gammaBP(ECTV) consists of an IFN-gammaR1 ligand-binding domain and a 57-aa helix-turn-helix (HTH) motif that is structurally related to the transcription factor TFIIA. The HTH motif forms a tetramerization domain that results in an IFN-gammaBP(ECTV)/IFN-gamma complex containing four IFN-gammaBP(ECTV) chains and two IFN-gamma dimers. The structure, combined with biochemical and cell-based assays, demonstrates that IFN-gammaBP(ECTV) tetramers are required for efficient IFN-gamma antagonism.