Monoclonal antibody-mediated enhancement of dengue virus infectionin vitroandin vivoand strategies for prevention

Abstract

antibody-dependent enhancement ͉ nonhuman primate model ͉ Fc mutations ͉ cross-reactive mAb T he four dengue virus (DENV) serotypes (DENV-1 to DENV-4) are the most important arthropod-borne flaviviruses in terms of morbidity and geographic distribution. Up to 100 million DENV infections occur every year, mostly in tropical and subtropical areas where vector mosquitoes are abundant (1). Infection with any of the DENV serotypes may be asymptomatic or may lead to classic dengue fever or more severe dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which are increasingly common in the dengue endemic areas. Immunity to the same virus serotype (homotypic immunity) is life-long, whereas immunity to different serotypes (heterotypic immunity) lasts 2-3 months so that infection with a different serotype virus is possible (2). DHF/DSS often occurs in patients with second, heterotypic DENV infections or in infants with maternally transferred dengue immunity (3, 4). Severe dengue is a major cause of hospitalization, and fatality rates vary from Ͻ1% to 5% in children.Antibody-dependent enhancement (ADE) has been proposed as an underlying pathogenic mechanism of DHF/DSS (3). ADE occurs because preexisting subneutralizing antibodies and the infecting DENV form complexes that bind to Fc receptorbearing cells, leading to increased virus uptake and replication (4). ADE has been repeatedly demonstrated in vitro using dengue immune sera or monoclonal antibodies and cells of monocytic and recently, B lymphocytic lineages bearing Fc receptors (5-7). ADE of DENV-2 infection has also been demonstrated in monkeys infused with a human dengue immune serum (8).Infection with DENV or any other flavivirus induces broadly cross-reactive but weak or nonneutralizing antibodies (9, 10). These antibodies remain detectable for a long period and rise rapidly during a subsequent heterotypic infection as a result of an anamnestic response. A major subset of these cross-reactive antibodies is directed to immuno-dominant epitopes involving determinants mapped to the flavivirus-conserved fusion peptide in the envelope glycoprotein (E) (11-13). The functional activities of these cross-reactive antibodies are not well characterized.We have identified chimpanzee-human chimeric IgG1 mAbs capable of neutralizing or binding to one or more DENV serotypes (14, 15). Cross-reactive IgG 1A5 neutralizes DENV-1 and DENV-2 more efficiently than DENV-3 and DENV-4, and type-specific IgG 5H2 neutralizes DENV-4 at a high titer (14,15). Analysis of antigenic variants has localized the IgG 1A5 binding site to the conserved fusion peptide in E (11). Thus, IgG 1A5 shares many characteristics with the cross-reactive antibodies detected in flavivirus infections.We investigated the ability of IgG 1A5 to mediate enhancement of DENV replication in monocyte-derived cell lines and in juvenile rhesus monkeys after passive transfer. We also explored strategies to reduce ADE by mutational analysis of the key structures in the Fc of IgG 1A5. A 9-aa deletion at the N termin...

Structural basis of potent Zika–dengue virus antibody cross-neutralization

“…Our results suggest that the epitope targeted by the EDE1 bnAbs is better suited for developing an epitope-focused vaccine for viruses in the ZIKV/DENV super serogroup than is the FLE, which induces poorly neutralizing and strongly infection-enhancing antibodies [12][13][14] . The EDE1 is also better suited than the related EDE2 epitope: although the EDE1 bnAbs require an E dimer to bind, the actual binding determinants are centred on the b strand and on the highly conserved, E-dimer-exposed elements of the fusion loop, as shown by the comparison between their binding to DENV-2 and ZIKV sE.…”

“…One surface exposed by this 'breathing' is the fusionloop epitope (FLE), which is a dominant cross-reactive antigenic site 9 . Although antibodies to this site can protect by complement-mediated mechanisms, as shown in a mouse model for West Nile virus 10 , they are poorly neutralizing and lead to antibody-dependent enhancement [11][12][13][14][15] , thereby aggravating Flavivirus pathogenesis and complicating the development of safe and effective vaccines.…”

Dengue: a continuing global threat

“…The positive singlestrand RNA genome (FIG. 3), which is approximately 11 kb in length, has a single open reading frame that encodes three structural proteins -the capsid (C), membrane (M) and envelope (E) glycoproteins -and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5 [18][19][20] . ADE occurs when mononuclear phagocytes are infected through their Fc receptors by immune complexes that form between DENVs and non-neutralizing antibodies.…”

“…There is also evidence of abundant replication of DENVs in liver parenchymal cells and in macrophages in lymph nodes, liver and spleen, as well as in peripheral blood monocytes 17 . Both in vitro and in vivo, macrophages and monocytes participate in antibody-dependent enhancement (ADE) [18][19][20] . ADE occurs when mononuclear phagocytes are infected through their Fc receptors by immune complexes that form between DENVs and non-neutralizing antibodies.…”

Formation of Infectious Dengue Virus–Antibody Immune Complex In Vivo in Marmosets (Callithrix jacchus) After Passive Transfer of Anti-Dengue Virus Monoclonal Antibodies and Infection with Dengue Virus

“…15 ADE has also been shown in mouse and non-human primate models, in which passive transfer of a cross-reactive monoclonal Ab (mAb) and sera from dengue patients resulted in higher viremia levels. [16][17][18] However, the formation of infectious virus-immune complex in these primate models has not been shown.…”