Biology subjects

Hannula, L.

Publications and source records attributed to Hannula, L..

3 recordsLinked to original sources

bioRxiv2024

Structural landscape of engineered multivalent antibody fragments and their application as crystallization scaffolds

Multivalent recombinant antibody fragments, "multibodies", are produced by fusing antibody VH and VL domains and provide the ability to bind multiple antigens simultaneously. The oligomeric state of a multibody is believed to be determined by the length of the linker region between the V-domains, with longer linkers resulting in diabodies (60 kDa) and shorter linkers leading to the formation of triabodies (90 kDa), tetrabodies (120 kDa), and larger oligomers. In this work, we investigate this design space by engineering multibodies from the sequences of human mAbs CR57 and Imdevimab, and resolve their crystal structures at 2.25 [A] and 2.55 [A] resolution, respectively. Our results show that despite minimizing the length of the hinge region between the V-domains, these constructs form diabodies. This indicates that linker length is not the sole determinant of a multibodys oligomeric state, and additional factors such as the mAb origin species and light chain type must also be taken into account when designing multibodies. Moreover, we confirmed that the native paratope of the antibody is well- maintained in the diabody format, and conducted a proof-of-concept trial comparing the crystallization propensity of a diabody versus a Fab in antibody-antigen complex crystallization. Our results show that a diabody can promote crystallization more effectively than a Fab, demonstrating the potential of diabodies as crystallization scaffolds for antibody- antigen complexes.

molecular biology↗

bioRxiv2022

Nanobody engineering for SARS-CoV-2 neutralization and detection

In response to the ongoing SARS-CoV-2 pandemic, the quest for coronavirus inhibitors has inspired research on a variety of small proteins beyond conventional antibodies, including robust single-domain antibody fragments, nanobodies. Here, we explore the potential of nanobody engineering in the development of antivirals and diagnostic tools. Through fusion of nanobody domains that target distinct binding sites, we engineered multimodular nanobody constructs that neutralize wild-type SARS-CoV-2 and the Alpha and Delta variants with high potency, with IC50 values up to 50 pM. However, we observed a limitation in the efficacy of multimodular nanobodies against the Beta (B.1.351) and Omicron variants (B.1.1.529), underlining the importance of accounting for viral evolution in the design of biologics. To further explore the applications of nanobody engineering in outbreak management, we present a novel detection assay, based on fusions of nanobodies with fragments of NanoLuc luciferase that can detect sub-nanomolar quantities of the SARS-CoV-2 spike protein in a single step. Our work showcases the potential of nanobody engineering to combat emerging infectious disease.

microbiology↗

bioRxiv2021

Intranasal inhibitor blocks Omicron and other variants of SARS-CoV-2

The recent emergence of novel SARS-CoV-2 variants capable of efficiently escaping neutralizing antibodies emphasizes the need for prophylactic strategies to complement vaccination in fighting the COVID-19 pandemic. Nasal epithelium is rich in the ACE2 receptor and important for SARS-CoV-2 transmission by supporting early viral replication before seeding to the lung1. Intranasal administration of SARS-CoV-2 neutralizing antibodies or antibody fragments has shown encouraging potential as a protective measure in animal models2-5. However, there remains a dire need for SARS-CoV-2 blocking agents that are less vulnerable to mutational variation in the neutralization epitopes of the viral spike glycoprotein and more economical to produce in large scale. Here we describe TriSb92, a highly manufacturable and extremely stable trimeric human SH3 domain-derived antibody mimetic targeted against a conserved region in the receptor-binding domain of spike. TriSb92 potently neutralizes SARS-CoV-2 and its variants of concern, including Omicron BA.5 as well as the latest and most immunoevasive variants like BF.7, XBB, and BQ.1.1. Intranasal administration of a modest dose of TriSb92 (5 or 50 micrograms) as early as eight hours before a challenge with SARS-CoV-2 efficiently protected mice from infection, and was still effective even when given 4 h after the viral challenge. The target epitope of TriSb92 was defined by cryo-EM, which revealed triggering of a conformational shift in the spike trimer rather than competition for ACE2 binding as the molecular basis of its strong inhibitory action. The high potency and robust biochemical properties of TriSb92 together with the remarkable resistance of its inhibitory action against viral sequence evolution suggest that TriSb92 could be useful as a nasal spray for protecting susceptible individuals from SARS-CoV-2 infection.

microbiology↗