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Engineering a novel IgG-like bispecific antibody against enterovirus A71.

ABSTRACT: Frequent outbreaks of enterovirus A71 (EVA71) occur in the Asia-Pacific area, and these are closely associated with severe neurological symptoms in young children. No effective antiviral therapy is currently available for the treatment of EVA71 infection. The development of monoclonal antibodies (mAbs) has demonstrated promise as a novel therapy for the prevention and treatment of infectious diseases. Several medical conditions have been treated using bispecific or multi-specific antibodies that recognize two or more distinct epitopes simultaneously. However, bispecific or multi-specific antibodies often encounter protein expression and product stability problems. In this study, we developed an IgG-like bispecific antibody (E18-F1) comprising two anti-EVA71 antibodies: E18 mAb and llama-derived F1 single-domain antibody. E18-F1 was demonstrated to exhibit superior binding affinity and antiviral activity compared with E18 or F1. Additionally, E18-F1 not only improved survival rate, but also reduced clinical signs in human SCARB2 receptor (hSCARB2) transgenic mice challenged with a lethal dose of EVA71. Altogether, our results reveal that E18-F1 is a simple format bispecific antibody with promising antiviral activity for EVA71.

SUBMITTER: Wang HC

PROVIDER: S-EPMC8164134 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Antiviral Activity of a Llama-Derived Single-Domain Antibody against Enterovirus A71.

Project description:In the past few decades, enterovirus A71 (EVA71) has caused devastating outbreaks in the Asia-Pacific region, resulting in serious sequelae in infected young children. No preventive or therapeutic interventions are currently available for curing EVA71 infection, highlighting a great unmet medical need for this disease. Here, we showed that one novel single-domain antibody (sdAb), F1, isolated from an immunized llama, could alleviate EVA71 infection both in vitro and in vivo We also confirmed that the sdAb clone F1 recognizes EVA71 through a novel conformational epitope comprising the highly conserved region of VP3 capsid protein by using competitive-binding and overlapping-peptide enzyme-linked immunosorbent assays (ELISAs). Because of the virion's icosahedral structure, we reasoned that adjacent epitopes must be clustered within molecular ranges that may be simultaneously bound by an engineered antibody with multiple valency. Therefore, two single-domain binding modules (F1) were fused to generate an sdAb-in-tandem design so that the capture of viral antigens could be further increased by valency effects. We showed that the tetravalent construct F1×F1-hFc, containing two sdAb-in-tandem on a fragment crystallizable (Fc) scaffold, exhibits more potent neutralization activity against EVA71 than does the bivalent sdAb F1-hFc by at least 5.8-fold. We also demonstrated that, using a human scavenger receptor class B member 2 (hSCARB2) transgenic mouse model, a half dose of the F1×F1-hFc provided better protection against EVA71 infection than did the F1-hFc. Thus, our study furnishes important insights into multivalent sdAb engineering against viral infection and provides a novel strategic deployment approach for preparedness of emerging infectious diseases such as EVA71.

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Structure activity relationship of novel antiviral nucleosides against Enterovirus A71.

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