An affinity-matured human monoclonal antibody targeting fusion loop epitope of dengue virus with in vivo therapeutic potency

Tomohiro Kotaki,Edgar Davidson,Kris Cahyo Mulyatno,Tamaki Okabayashi,Soegeng Soegijanto,Ariadna Grinyo-Escuer,Ken-Ichiro Ono,Teguh Hari Sucipto,Orapim Puiprom,Siti Churrotin,Takeshi Kurosu,Benjamin J Doranz,Masanori Kameoka

doi:10.1038/s41598-021-92403-9

Abstract

Dengue virus (DENV), from the genus flavivirus of the family flaviviridae, causes serious health problems globally. Human monoclonal antibodies (HuMAb) can be used to elucidate the mechanisms of neutralization and antibody-dependent enhancement (ADE) of DENV infections, leading to the development of a vaccine or therapeutic antibodies. Here, we generated eight HuMAb clones from an Indonesian patient infected with DENV. These HuMAbs exhibited the typical characteristics of weak neutralizing antibodies including high cross-reactivity with other flaviviruses and targeting of the fusion loop epitope (FLE). However, one of the HuMAbs, 3G9, exhibited strong neutralization (NT50 < 0.1 μg/ml) and possessed a high somatic hyper-mutation rate of the variable region, indicating affinity-maturation. Administration of this antibody significantly prolonged the survival of interferon-α/β/γ receptor knockout C57BL/6 mice after a lethal DENV challenge. Additionally, Fc-modified 3G9 that had lost their in vitro ADE activity showed enhanced therapeutic potency in vivo and competed strongly with an ADE-prone antibody in vitro. Taken together, the affinity-matured FLE-targeting antibody 3G9 exhibits promising features for therapeutic application including a low NT50 value, potential for treatment of various kinds of mosquito-borne flavivirus infection, and suppression of ADE. This study demonstrates the therapeutic potency of affinity-matured FLE-targeting antibodies.

Highlights

Dengue virus (DENV), from the genus flavivirus of the family flaviviridae, causes serious health problems globally
One of the mechanisms hypothesized to cause a higher risk of severe dengue is the antibody-dependent enhancement (ADE) of the infection, whereby pre-existing anti-DENV antibodies induced by the primary infection or vaccination facilitate subsequent DENV infections of Fc receptor-positive cells like m acrophages[6]
We established eight Human monoclonal antibodies (HuMAb) clones from a blood specimen of an Indonesian patient with dengue using SPYMEG cells that belong to a human hybridoma fusion partner cell line[37,38]

Summary

Introduction

Dengue virus (DENV), from the genus flavivirus of the family flaviviridae, causes serious health problems globally. Neutralization suppresses viremia, resulting in protection against DENV infection, while ADE increases viremia, and this is associated with severe dengue[7] This phenomenon might have increased the risk of developing severe dengue disease among seronegative people who have received vaccinations of CYD-TDV, which is the only licensed dengue v accine[8,9]. The viral particle is assembled in the lumen of the endoplasmic reticulum, where nucleocapsid (viral RNA complexed with the C protein) is incorporated into the lipid bilayer containing prM and E proteins[1] As this immature viral particle traffics through the trans-Golgi network, a host serine protease (furin) cleaves the prM protein from the immature virus, resulting in maturation. The maturity and breathing of virions have an impact on the recognition of antibodies and, thereby, affect their neutralizing and enhancing activities[15,16]

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