A dual-targeting approach using a human bispecific antibody against the receptor-binding domain of the Middle East Respiratory Syndrome Coronavirus

The emergence of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) has posed a significant global health concern due to its severe respiratory illness and high fatality rate. Currently, despite the potential for resurgence, there are no specific treatments for MERS-CoV, and only supportive care is available. Our study aimed to address this therapeutic gap by developing a potent neutralizing bispecific antibody (bsAb) against MERS-CoV. Initially, we isolated four human monoclonal antibodies (mAbs) that specifically target the MERS-CoV receptor-binding domain (RBD) using phage display technology and an established human antibody library. Among these four selected mAbs, our intensive in vitro functional analyses showed that the MERS-CoV RBD-specific mAb K111.3 exhibited the most potent neutralizing activity against MERS-CoV pseudoviral infection and the molecular interaction between MERS-CoV RBD and human dipeptidyl peptidase 4. Consequently, we engineered a novel bsAb, K207.C, by utilizing K111.3 as the IgG base and fusing it with the single-chain variable fragment of its non-competing pair, K111.1. This engineered bsAb showed significantly enhanced neutralization potential against MERS-CoV compared to its parental mAb. These findings suggest that K207.C may serve as a potential candidate for effective MERS-CoV neutralization, further highlighting the promise of the bsAb dual-targeting approach in MERS-CoV neutralization.

Development, High-Throughput Profiling, and Biopanning of a Large Phage Display Single-Domain Antibody Library

Immunoglobulin G-based monoclonal antibodies (mAbs) have been effective in treating various diseases, but their large molecular size can limit their penetration of tissue and efficacy in multifactorial diseases, necessitating the exploration of alternative forms. In this study, we constructed a phage display library comprising single-domain antibodies (sdAbs; or "VHHs"), known for their small size and remarkable stability, using a total of 1.6 × 109 lymphocytes collected from 20 different alpacas, resulting in approximately 7.16 × 1010 colonies. To assess the quality of the constructed library, next-generation sequencing-based high-throughput profiling was performed, analyzing approximately 5.65 × 106 full-length VHH sequences, revealing 92% uniqueness and confirming the library's diverse composition. Systematic characterization of the library revealed multiple sdAbs with high affinity for three therapeutically relevant antigens. In conclusion, our alpaca sdAb phage display library provides a versatile resource for diagnostics and therapeutics. Furthermore, the library's vast natural VHH antibody repertoire offers insights for generating humanized synthetic sdAb libraries, further advancing sdAb-based therapeutics.

Development and Characterization of Phage Display-Derived Monoclonal Antibodies to the S2 Domain of Spike Proteins of Wild-Type SARS-CoV-2 and Multiple Variants

The rapid emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has resulted in the ongoing global coronavirus disease 2019 (COVID-19) pandemic. Thus, the rapid development of a platform to detect a broad range of SARS-CoV-2 variants is essential for successful COVID-19 management. In this study, four SARS-CoV-2 spike protein-specific single-chain variable fragments (scFvs) were isolated from a synthetic antibody library using phage display technology. Following the conversion of these scFvs into monoclonal antibodies (mAbs) (K104.1-K104.4) and production and purification of the mAbs, the antibody pair (K104.1 and K104.2) that exhibited the highest binding affinity (K104.1 and K104.2, 1.3 nM and 1.9 nM) was selected. Biochemical analyses revealed that this antibody pair specifically bound to different sites on the S2 subunit of the spike protein. Furthermore, we developed a highly sensitive sandwich immunoassay using this antibody pair that accurately and quantitatively detected the spike proteins of wild-type SARS-CoV-2 and multiple variants, including Alpha, Beta, Gamma, Delta, Kappa, and Omicron, in the picomolar range. Conclusively, the novel phage display-derived mAbs we have developed may be useful for the rapid and efficient detection of the fast-evolving SARS-CoV-2.

Differences in microstructural alterations of the hippocampus in Alzheimer disease and idiopathic normal pressure hydrocephalus: a diffusion tensor imaging study

BACKGROUND AND PURPOSE

DTI can be used to assess the degradation of WM tracts by measuring the FA and MD. Decreased FA/increased MD values in the AD hippocampus have been reported by many studies. In contrast, only a few studies reported on hydrocephalus by using the DTI technique. In elderly patients with dementia and with dilated ventricles, it is often difficult to differentiate iNPH from AD with visual measurements on MR imaging. The aim of this study was to investigate the changes of microstructural integrity of the hippocampus in iNPH by using DTI and determining whether this method could be a new diagnostic tool to differentiate iNPH from AD.

MATERIALS AND METHODS

We recruited 43 participants (15 healthy controls, 15 patients with AD, and 13 patients with iNPH). The FA and MD values were measured by using the region-of-interest method in the hippocampal head, body, and tail on both sides. Clinical history, neurologic examination, and neuropsychological assessment were included.

RESULTS

The FA values were the lowest in the patients with AD, the patients with iNPH, and the healthy controls in this order. The MD values were the highest in the same order. These findings were consistent in the 3 subdivisions of the bilateral hippocampal regions. Hippocampal volume was not different between patients with iNPH and AD.

CONCLUSIONS

The microstructural alterations of the hippocampus were more sensitive than the volumetric changes in AD and iNPH. DTI analysis might be a useful tool for discriminating AD from iNPH.