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The rapid evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants has emphasized the need to identify antibodies with broad neutralizing capabilities to inform future monoclonal therapies and vaccination strategies. Herein, we identified S728-1157, a broadly neutralizing antibody (bnAb) targeting the receptor-binding site (RBS) that was derived from an individual previously infected with WT SARS-CoV-2 prior to the spread of variants of concern (VOCs). S728-1157 demonstrated broad cross-neutralization of all dominant variants, including D614G, Beta, Delta, Kappa, Mu, and Omicron (BA.1/BA.2/BA.2.75/BA.4/BA.5/BL.1/XBB). Furthermore, S728-1157 protected hamsters against in vivo challenges with WT, Delta, and BA.1 viruses. Structural analysis showed that this antibody targets a class 1/RBS-A epitope in the receptor binding domain via multiple hydrophobic and polar interactions with its heavy chain complementarity determining region 3 (CDR-H3), in addition to common motifs in CDR-H1/CDR-H2 of class 1/RBS-A antibodies. Importantly, this epitope was more readily accessible in the open and prefusion state, or in the hexaproline (6P)-stabilized spike constructs, as compared with diproline (2P) constructs. Overall, S728-1157 demonstrates broad therapeutic potential and may inform target-driven vaccine designs against future SARS-CoV-2 variants., Introduction Since the start of the pandemic in December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has led to over 660 million cases of coronavirus disease 2019 [...]

Ebolaviruses cause severe disease in humans, and identification of monoclonal antibodies (mAbs) that are effective against multiple ebolaviruses are important for therapeutics development. Here we describe a distinct class of broadly neutralizing human mAbs with protective capacity against three ebolaviruses infectious for humans: Ebola (EBOV), Sudan (SUDV), and Bundibugyo (BDBV) viruses. We isolated mAbs from human survivors of ebolavirus disease and identified a potent mAb, EBOV-520, which bound to an epitope in the glycoprotein (GP) base region. EBOV-520 efficiently neutralized EBOV, BDBV, and SUDV and also showed protective capacity in relevant animal models of these infections. EBOV-520 mediated protection principally by direct virus neutralization and exhibited multifunctional properties. This study identified a potent naturally occurring mAb and defined key features of the human antibody response that may contribute to broad protection. This multifunctional mAb and related clones are promising candidates for development as broadly protective pan-ebolavirus therapeutic molecules.

Although broadly protective, stem-targeted Abs against the Influenza A virus hemagglutinin (HA) have been well studied, very limited information is available on Abs that broadly recognize the head domain. We determined the crystal structure of the HA protein of the avian H7N9 influenza virus in complex with a pan-H7, non-neutralizing, protective human Ab. The structure revealed a B cell epitope in the HA head domain trimer interface (TI). This discovery of a second major protective TI epitope supports a model in which uncleaved HA trimers exist on the surface of infected cells in a highly dynamic state that exposes hidden HA head domain features., Introduction Avian influenza A virus (IAV) H7N9 strains have caused several outbreaks in humans, with high morbidity and mortality. The potential for H7N9 viruses to acquire the capacity for human-to-human [...]

Adjuvants are central to the efficacy of subunit vaccines. Aluminum hydroxide (alum) is the most commonly used vaccine adjuvant, yet its adjuvanticity is often weak and mechanisms of triggering antibody responses remain poorly understood. We demonstrate that site-specific modification of immunogens with short peptides composed of repeating phosphoserine (pSer) residues enhances binding to alum and prolongs immunogen bioavailability. The pSer-modified immunogens formulated in alum elicited greatly increased germinal center, antibody, neutralizing antibody, memory and long-lived plasma cell responses compared to conventional alum-adsorbed immunogens. Mechanistically, pSer-immunogen:alum complexes form nanoparticles that traffic to lymph nodes and trigger B cell activation through multivalent and oriented antigen display. Direct uptake of antigen-decorated alum particles by B cells upregulated antigen processing and presentation pathways, further enhancing B cell activation. These data provide insights into mechanisms of action of alum and introduce a readily translatable approach to significantly improve humoral immunity to subunit vaccines using a clinical adjuvant. Alum coupled to protein immunogens via site-specific phosphoserine-containing linkers enhances long-lived B cell responses and can selectively direct antibodies toward protective neutralizing epitopes., Author(s): Tyson J. Moyer [sup.1] [sup.2] , Yu Kato [sup.2] [sup.3] , Wuhbet Abraham [sup.1] , Jason Y. H. Chang [sup.1] , Daniel W. Kulp [sup.2] [sup.4] [sup.5] , Nicki [...]

Broadly reactive antibodies targeting the influenza A virus hemagglutinin (HA) head domain are thought to be rare and to require extensive somatic mutations or unusual structural features to achieve breadth against divergent HA subtypes. Here we describe common genetic and structural features of protective human antibodies from several individuals recognizing the trimer interface (TI) of the influenza A HA head, a recently identified site of vulnerability. We examined the sequence of Tl-reactive antibodies, determined crystal structures for TI antibody-antigen complexes, and analyzed the contact residues of the antibodies on HA to discover common genetic and structural features of TI antibodies. Our data reveal that many TI antibodies are encoded by a light chain variable gene segment incorporating a shared somatic mutation. In addition, these antibodies have a shared acidic residue in the heavy chain despite originating from diverse heavy chain variable gene segments. These studies show that the TI region of influenza A HA is a major antigenic site with conserved structural features that are recognized by a common human B cell public clonotype. The canonical nature of this antibody-antigen interaction suggests that the TI epitope might serve as an important target for structure-based vaccine design., Introduction Influenza A virus (IAV) is one of the most common causes of severe lower respiratory illness in humans and exhibits a wide antigenic diversity in circulating field strains. Seasonal [...]

Purpose: This study reports age 5 morphology and syntax skills in late talkers identified at age 2 (n = 34) and typically developing comparison children (n = 20). Results: The late talkers manifested significant morphological delays at ages 3 and 4 relative to comparison peers. Based on the 14 morphemes analyzed at age 5, the only significant group difference was on the third person regular "-s" inflection. This was also the only significant difference when we compared late talkers with continuing delay, late bloomers (who scored within 1 standard deviation of the comparison group in mean length of utterance), and typically developing peers. The late talker and comparison children differed greatly in mean total scores on the Index of Productive Syntax (Scarborough, 1990), a measure of syntactic complexity. The group with continuing delay scored significantly lower on the IPSyn than the late bloomer and typically developing groups, which did not differ from each other. Conclusions: Findings are consistent with the higher order language group differences found through adolescence in these late talkers relative to comparison peers with similar socioeconomic status and similar nonverbal abilities, supporting the notion that late talkers have an ongoing weakness in language endowment that manifests differently over the course of development.

Nanobodies bind a target antigen with a kinetic profile similar to a conventional antibody, but exist as a single heavy chain domain that can be readily multimerized to engage antigen via multiple interactions. Presently, most nanobodies are produced by immunizing camelids; however, platforms for animal-free production are growing in popularity. Here, we describe the development of a fully synthetic nanobody library based on an engineered human VH3-23 variable gene and a multispecific antibody-like format designed for biparatopic target engagement. To validate our library, we selected nanobodies against the SARS-CoV-2 receptor-binding domain and employed an on-yeast epitope binning strategy to rapidly map the specificities of the selected nanobodies. We then generated antibody-like molecules by replacing the VH and VL domains of a conventional antibody with two different nanobodies, designed as a molecular clamp to engage the receptor-binding domain biparatopically. The resulting bispecific tetra-nanobody immunoglobulins neutralized diverse SARS-CoV-2 variants with potencies similar to antibodies isolated from convalescent donors. Subsequent biochemical analyses confirmed the accuracy of the on-yeast epitope binning and structures of both individual nanobodies, and a tetra-nanobody immunoglobulin revealed that the intended mode of interaction had been achieved. This overall workflow is applicable to nearly any protein target and provides a blueprint for a modular workflow for the development of multispecific molecules. [ABSTRACT FROM AUTHOR]

Author(s): Robert N. Kirchdoerfer [1]; Christopher A. Cottrell [1]; Nianshuang Wang [2]; Jesper Pallesen [1]; Hadi M. Yassine [3]; Hannah L. Turner [1]; Kizzmekia S. Corbett [3]; Barney S. Graham [...]

Purpose: This study reports age 5 morphology and syntax skills in late talkers identified at age 2 (n = 34) and typically developing comparison children (n = 20). Results: The late talkers manifested significant morphological delays at ages 3 and 4 relative to comparison peers. Based on the 14 morphemes analyzed at age 5, the only significant group difference was on the third person regular -s inflection. This was also the only significant difference when we compared late talkers with continuing delay, late bloomers (who scored within 1 standard deviation of the comparison group in mean length of utterance), and typically developing peers. The late talker and comparison children differed greatly in mean total scores on the Index of Productive Syntax (Scarborough, 1990), a measure of syntactic complexity. The group with continuing delay scored significantly lower on the IPSyn than the late bloomer and typically developing groups, which did not differ from each other. Conclusions: Findings are consistent with the higher order language group differences found through adolescence in these late talkers relative to comparison peers with similar socioeconomic status and similar nonverbal abilities, supporting the notion that late talkers have an ongoing weakness in language endowment that manifests differently over the course of development., Epidemiological studies indicate that approximately 10% to 15% of 2-year-olds are categorized as late talkers (LTs; Law, 2013; Taylor, Zubrick, & Rice, 2013). Furthermore, late talking is one of the [...]