#ADE of #influenza #disease promoted by increase in #hemagglutinin stem flexibility and virus #fusion kinetics (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Antibody-dependent enhancement of influenza disease promoted by increase in hemagglutinin stem flexibility and virus fusion kinetics

Katie L. Winarski, Juanjie Tang, Laura Klenow, Jeehyun Lee, Elizabeth M. Coyle, Jody Manischewitz, Hannah L. Turner, Kazuyo Takeda, Andrew B. Ward, Hana Golding, and Surender Khurana

PNAS first published July 11, 2019 / DOI: https://doi.org/10.1073/pnas.1821317116

Edited by Robert G. Webster, St. Jude Children’s Research Hospital, Memphis, TN, and approved June 19, 2019 (received for review December 14, 2018)



Next-generation influenza vaccines and broadly neutralizing antibodies (bNAbs) are in clinical development. Some of these do not block virus–receptor interactions and thus are predicted to provide protection via alternative mechanisms at the postentry stage or use Fc-dependent mechanisms. Nonneutralizing antibodies have the potential to mediate enhancement of respiratory disease (ERD). Our study describes ADE with two different functional MAbs that destabilized HA stem domain, increased influenza virus fusion kinetics, and led to enhanced lung pathology and ERD in a dose-dependent manner in a mice model. This study underlines careful preclinical evaluation of next-generation influenza vaccines or antibody-based therapeutics that do not block influenza virus receptor binding.



Several next-generation (universal) influenza vaccines and broadly neutralizing antibodies (bNAbs) are in clinical development. Some of these mediate inhibitions of virus replication at the postentry stage or use Fc-dependent mechanisms. Nonneutralizing antibodies have the potential to mediate enhancement of viral infection or disease. In the current study, two monoclonal antibodies (MAbs) 72/8 and 69/1, enhanced respiratory disease (ERD) in mice following H3N2 virus challenge by demonstrating increased lung pathology and changes in lung cytokine/chemokine levels. MAb 78/2 caused changes in the lung viral loads in a dose-dependent manner. Both MAbs increased HA sensitivity to trypsin cleavage at a higher pH range, suggesting MAb-induced conformational changes. pHrodo-labeled virus particles’ entry and residence time in the endocytic compartment were tracked during infection of Madin-Darby canine kidney (MDCK) cells. Both MAbs reduced H3N2 virus residence time in the endocytic pathway, suggesting faster virus fusion kinetics. Structurally, 78/2 and 69/1 Fabs bound the globular head or base of the head domain of influenza hemagglutinin (HA), respectively, and induced destabilization of the HA stem domain. Together, this study describes Mab-induced destabilization of the influenza HA stem domain, faster kinetics of influenza virus fusion, and ERD in vivo. The in vivo animal model and in vitro assays described could augment preclinical safety evaluation of antibodies and next-generation influenza vaccines that generate antibodies which do not block influenza virus–receptor interaction.

universal – stem – influenza – antibody-dependent enhancement (ADE) – vaccine



1 K.L.W., J.T., and L.K. contributed equally to this work.

2 To whom correspondence may be addressed. Email: Surender.Khurana@fda.hhs.gov.

Author contributions: S.K. designed research; K.L.W., J.T., L.K., J.L., E.M.C., J.M., H.L.T., K.T., A.B.W., and S.K. performed research; K.L.W., J.T., L.K., H.L.T., K.T., A.B.W., and S.K. analyzed data; and A.B.W., H.G., and S.K. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1821317116/-/DCSupplemental.

Published under the PNAS license.

Keywords: Influenza A; Monoclonal antibodies; Vaccines; Antibody Dependent Enhancement.



#Zika Virus-Immune #Plasmas from Symptomatic and Asymptomatic Individuals Enhance Zika #Pathogenesis in #Adult and #Pregnant Mice (mBio, abstract)

[Source: mBio, full page: (LINK). Abstract, edited.]

Zika Virus-Immune Plasmas from Symptomatic and Asymptomatic Individuals Enhance Zika Pathogenesis in Adult and Pregnant Mice

Byoung-Shik Shim, Young-Chan Kwon, Michael J. Ricciardi, Mars Stone, Yuka Otsuka, Fatma Berri, Jaclyn M. Kwal, Diogo M. Magnani, Cody B. Jackson, Audrey S. Richard, Philip Norris,Michael Busch, Christine L. Curry, Michael Farzan, David Watkins, Hyeryun Choe

Mark R. Denison, Editor

DOI: 10.1128/mBio.00758-19



Preexisting immunity against dengue virus or West Nile virus was previously reported to mediate antibody-dependent enhancement (ADE) of Zika virus (ZIKV) infection in a mouse model. We show here that ZIKV-immune plasma samples from both symptomatic and asymptomatic individuals mediated ZIKV ADE of infection in vitro and in mice. In a lethal infection model with a viral inoculum 10 times higher, both ADE and protection were observed, depending on the amount of infused immune plasma. In a vertical-transmission model, ZIKV-immune plasma infused to timed pregnant mice increased fetal demise and decreased the body weight of surviving fetuses. Depletion of IgG from an immune plasma abolished ADE of infection, and the presence of purified IgG alone mediated ADE of infection. Higher viral loads and proinflammatory cytokines were detected in mice treated with ZIKV-immune plasma samples compared to those receiving control plasma. Together, these data show that passive immunization with homotypic ZIKV antibodies, depending on the concentration, could either worsen or limit a subsequent ZIKV infection.



Antibody-dependent enhancement (ADE) of virus infection is common to many viruses and is problematic when plasma antibody levels decline to subneutralizing concentrations. ADE of infection is especially important among flaviviruses, many of which are the cause of global health problems. Recently, human plasma samples immune to heterologous flaviviruses were shown to promote Zika virus (ZIKV) infection. Here we showed in immunocompromised mouse models that homologous immune plasma samples protect mice from subsequent infection at high antibody concentrations but that they mediate ADE of infection and increase ZIKV pathogenesis in adult mice and fetal demise during pregnancy at low concentrations.

Keywords: Zika Virus; ADE; Pregnancy; Immunopathology; Animal models.


#WNV #infection in individuals with pre-existing #Usutu virus #immunity, northern #Italy, 2018 (Euro Surveill., abstract)

[Source: Eurosurveillance, full page: (LINK). Abstract, edited.]

West Nile virus infection in individuals with pre-existing Usutu virus immunity, northern Italy, 2018

Alessandro Sinigaglia1, Monia Pacenti2, Thomas Martello1, Silvana Pagni1,2, Elisa Franchin1,2, Luisa Barzon1,2

Affiliations: 1 Department of Molecular Medicine, University of Padova, Padova, Italy; 2 Microbiology and Virology Unit, Padova University Hospital, Padova, Italy

Correspondence:  Luisa Barzon

Citation style for this article: Sinigaglia Alessandro, Pacenti Monia, Martello Thomas, Pagni Silvana, Franchin Elisa, Barzon Luisa. West Nile virus infection in individuals with pre-existing Usutu virus immunity, northern Italy, 2018. Euro Surveill. 2019;24(21):pii=1900261. https://doi.org/10.2807/1560-7917.ES.2019.24.21.1900261

Received: 27 Apr 2019;   Accepted: 22 May 2019



In 2018, there was a large West Nile virus (WNV) outbreak in northern Italy. We observed five atypical cases of WNV infection that were characterised by the presence of WNV RNA and WNV IgG at the time of diagnosis, but no IgM response during follow-up. Neutralisation assays demonstrated pre-existing Usutu virus immunity in all patients. Besides challenging diagnosis, the immunological crosstalk between the two viruses warrants further investigation on possible cross-protection or infection enhancement effects.

©  This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords: WNV; Usutu virus; ADE; Italy.


Cross- #Protection of #Dengue Virus #Infection against #Congenital #Zika #Syndrome, Northeastern #Brazil (Emerg Infect Dis., abstract)

[Source: US Centers for Disease Control and Prevention (CDC), Emerging Infectious Diseases Journal, full page: (LINK). Abstract, edited.]

Volume 25, Number 8—August 2019 / Research

Cross-Protection of Dengue Virus Infection against Congenital Zika Syndrome, Northeastern Brazil

Celia Pedroso1, Carlo Fischer1, Marie Feldmann1, Manoel Sarno, Estela Luz, Andrés Moreira-Soto, Renata Cabral, Eduardo Martins Netto, Carlos Brites, Beate M. Kümmerer, and Jan Felix Drexler

Author affiliations: Universidade Federal de Bahia, Salvador, Brazil (C. Pedroso, M. Sarno, E. Luz, R. Cabral, E. Martins Netto, C. Brites); Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin Humbolt-Universität zu Berlin and Berlin Institute of Health, Institute of Virology, Berlin, Germany (C. Fischer, A. Moreira-Soto, J.F. Drexler); University of Bonn Medical Centre, Bonn, Germany (M. Feldmann, B.M. Kümmerer); German Centre for Infection Research (B.M. Kümmerer, J.F. Drexler)



The Zika virus outbreak in Latin America resulted in congenital malformations, called congenital Zika syndrome (CZS). For unknown reasons, CZS incidence was highest in northeastern Brazil; one potential explanation is that dengue virus (DENV)–mediated immune enhancement may promote CZS development. In contrast, our analyses of historical DENV genomic data refuted the hypothesis that unique genome signatures for northeastern Brazil explain the uneven dispersion of CZS cases. To confirm our findings, we performed serotype-specific DENV neutralization tests in a case–control framework in northeastern Brazil among 29 Zika virus–seropositive mothers of neonates with CZS and 108 Zika virus–seropositive control mothers. Neutralization titers did not differ significantly between groups. In contrast, DENV seroprevalence and median number of neutralized serotypes were significantly lower among the mothers of neonates with CZS. Supported by model analyses, our results suggest that exposure to multitypic DENV infection may protect from, rather than enhance, development of CZS.

Keywords: Flavivirus; Dengue Fever; Zika Virus; A.D.E.; Congenital Zika Syndrome; Pregnancy; Brazil; Seroprevalence.


#Human #monoclonal #antibodies potently neutralize #Zika virus and select for escape mutations on the lateral ridge of the envelope protein (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Human monoclonal antibodies potently neutralize Zika virus and select for escape mutations on the lateral ridge of the envelope protein

Mark J. Bailey, Felix Broecker, Alec Freyn, Angela Choi, Julia A. Brown, Nadia Fedorova, Viviana Simon, Jean K. Lim, Matthew J. Evans, Adolfo García-Sastre, Peter Palese, Gene S. Tan

DOI: 10.1128/JVI.00405-19



The mosquito-borne Zika virus has been causing epidemic outbreaks on a global scale. Virus infection can result in severe disease in humans including microcephaly in newborns and Guillain-Barré syndrome in adults. Here, we characterized monoclonal antibodies isolated from a patient with an active Zika virus infection that potently neutralized virus infection in Vero cells at the nanogram per milliliter range. In addition, these antibodies enhanced internalization of virions into human leukemia K562 cells in vitro, indicating their possible ability to cause antibody-dependent enhancement of disease. Escape variants of the ZIKV MR766 strain to a potently neutralizing antibody, AC10, exhibited an amino acid substitution at residue S368 in the lateral ridge region of the envelope protein. Analysis of publicly availably ZIKV sequences revealed the S368 site to be conserved among the vast majority (97.6%) of circulating strains. We validated the importance of this residue by engineering a recombinant virus with an S368R point mutation that was unable to be fully neutralized by AC10. Four out of the twelve monoclonal antibodies tested were also unable to neutralize the virus with the S368R mutation, suggesting this region to be an important immunogenic epitope during human infection. Lastly, a time of addition infection assay further validated the escape variant and showed that all monoclonal antibodies inhibited virus binding to the cell surface. Thus, the present study demonstrates that the lateral ridge region of the envelope protein is likely an immunodominant, neutralizing epitope.



Zika virus (ZIKV) is a global health threat causing severe disease in humans including microcephaly in newborns and Guillain-Barré syndrome in adults. Here, we analyzed the human monoclonal antibody response to acute ZIKV infection and found that neutralizing antibodies could not elicit Fc-mediated immune effector functions but could potentiate antibody-dependent enhancement of disease. We further identified critical epitopes involved with neutralization by generating and characterizing escape variants by whole genome sequencing. We demonstrate the lateral ridge region, particularly the S368 amino acid site, is critical for neutralization by domain III specific antibodies.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Zika Virus; Monoclonal antibodies.


Development of Neutralizing #Antibodies against #Zika Virus Based on Its #Envelope #Protein Structure (Virol Sin., abstract)

[Source: Virologica Sinica, full page: (LINK). Abstract, edited.]

Development of Neutralizing Antibodies against Zika Virus Based on Its Envelope Protein Structure

Authors: Chunpeng Yang, Rui Gong, Natalia de Val

Open Access / Review / First Online: 24 April 2019



As we know more about Zika virus (ZIKV), as well as its linkage to birth defects (microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus disease has affected many countries and is becoming a major public health concern. To deal with the infection of ZIKV, plenty of experiments have been done on selection of neutralizing antibodies that can target the envelope (E) protein on the surface of the virion. However, the existence of antibody-dependent enhancement (ADE) effect might limit the use of them as therapeutic candidates. In this review, we classify the neutralizing antibodies against ZIKV based on the epitopes and summarize the resolved structural information on antibody/antigen complex from X-ray crystallography and cryo-electron microscopy (cryo-EM), which might be useful for further development of potent neutralizing antibodies and vaccines toward clinical use.

Keywords: Zika virus (ZIKV) – Envelope protein – Neutralizing antibody – X-ray crystallography – Cryo-electron microscopy (cryo-EM)

Keywords: Zika Virus; Monoclonal antibodies; A.D.E.


The possible role of cross-reactive #dengue virus #antibodies in #Zika virus #pathogenesis (PLoS Pathog., abstract)

[Source: PLoS Pathogens, full page: (LINK). Abstract, edited.]


The possible role of cross-reactive dengue virus antibodies in Zika virus pathogenesis

Thomas Langerak , Noreen Mumtaz , Vera I. Tolk, Eric C. M. van Gorp, Byron E. Martina, Barry Rockx, Marion P. G. Koopmans

Published: April 18, 2019 / DOI: https://doi.org/10.1371/journal.ppat.1007640



Zika virus (ZIKV) has been known for decades to circulate in Africa and Asia. However, major complications of a ZIKV infection have recently become apparent for reasons that are still not fully elucidated. One of the hypotheses for the seemingly increased pathogenicity of ZIKV is that cross-reactive dengue antibodies can enhance a ZIKV infection through the principle of antibody-dependent enhancement (ADE). Recently, ADE in ZIKV infection has been studied, but conclusive evidence for the clinical importance of this principle in a ZIKV infection is lacking. Conversely, the widespread circulation of ZIKV in dengue virus (DENV)-endemic regions raises new questions about the potential contribution of ZIKV antibodies to DENV ADE. In this review, we summarize the results of the evidence to date and elaborate on other possible detrimental effects of cross-reactive flavivirus antibodies, both for ZIKV infection and the risk of ZIKV-related congenital anomalies, DENV infection, and dengue hemorrhagic fever.


Citation: Langerak T, Mumtaz N, Tolk VI, van Gorp ECM, Martina BE, Rockx B, et al. (2019) The possible role of cross-reactive dengue virus antibodies in Zika virus pathogenesis. PLoS Pathog 15(4): e1007640. https://doi.org/10.1371/journal.ppat.1007640

Editor: Tom C. Hobman, University of Alberta, CANADA

Published: April 18, 2019

Copyright: © 2019 Langerak et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement ZikAlliance No 734548 and from the ZikaRisk project of ZonMw under project number 522003001. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Zika Virus; Dengue Fever; Immunopathology; A.D.E.