Fusion of the mouse IgG1 Fc domain to the VHH fragment (ARP1) enhances protection in a mouse model of rotavirus.

Gökçe Günaydın,Lennart Hammarström,Shengze Yu,Torbjörn Gräslund,Harold Marcotte

doi:10.1038/srep30171

Gökçe Günaydın, Lennart Hammarström + Show 3 more

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https://doi.org/10.1038/srep30171

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Abstract

A variable fragment of a heavy chain antibody (VHH) directed against rotavirus, also referred to as anti-rotavirus protein 1 (ARP1), was shown to confer protection against rotavirus induced diarrhea in infant mouse model of rotavirus induced diarrhea. In this study, we have fused the mouse IgG1 Fc to ARP1 to improve the protective capacity of ARP1 by inducing an Fc-mediated effector function. We have shown that the Fc-ARP1 fusion protein confers significantly increased protection against rotavirus in a neonatal mouse model of rotavirus-induced diarrhea by reducing the prevalence, duration and severity of diarrhea and the viral load in the small intestines, suggesting that the Fc part of immunoglobulins may be engaged in Fc-mediated neutralization of rotavirus. Engineered conventional-like antibodies, by fusion of the Fc part of immunoglobulins to antigen-specific heavy-chain only VHH fragments, might be applied to novel antibody-based therapeutic approaches to enhance elimination of pathogens by activation of distinct effector signaling pathways.

Highlights

Rotavirus is a non-enveloped double stranded RNA virus that is associated with a severe dehydrating diarrhea, infecting infants and children less than 5 years of age worldwide[1]
The anti-rotavirus activity and safety of the monovalent yeast-produced anti-rotavirus protein 1 (ARP1) fragment was previously demonstrated in our animal model, and in a clinical trial in children conducted in Bangladesh[20]
Aladin et al previously showed that ARP1 binds to the abundant and conserved middle layer protein VP6, explaining its broad neutralization capacity[21]

Summary

Introduction

Rotavirus is a non-enveloped double stranded RNA virus that is associated with a severe dehydrating diarrhea, infecting infants and children less than 5 years of age worldwide[1]. FcRn is the only receptor known to be engaged in bidirectional transcytosis of IgG across the mucosal epithelium in individuals at any age[10,11] It protects the captured antibody from lysosomal degradation and prolongs its half-life[12]. Another more recent and less-characterized receptor is the tripartite-motif containing protein 21 (TRIM21), a cytosolic Fc receptor found in all cells, but with high expression levels in immune and endothelial cells. Substitutions at position N434 (N434D, N434H or N434A) were previously shown to be crucial for TRIM21 mediated intracellular antibody-bound pathogen neutralization in primary cells, and for FcRn-mouse IgG1 interaction, respectively[13]. We evaluated the protection by Fc-ARP1 and mutant FcN434D-ARP1 fusion protein in a neonatal mouse model of rotavirus induced diarrhea as compared to ARP1 and bivalent (ARP1′)[2]

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