Dengue virus sero-cross-reactivity drives antibody-dependent enhancement of infection with zika virus

Abstract

Zika virus (ZIKV) was discovered in 1947 and was thought to lead to relatively mild disease. The recent explosive outbreak of ZIKV in South America has led to widespread concern, with reports of neurological sequelae ranging from Guillain Barré syndrome to microcephaly. ZIKV infection has occurred in areas previously exposed to dengue virus (DENV), a flavivirus closely related to ZIKV. Here we investigated the serological cross-reaction between the two viruses. Plasma immune to DENV showed substantial cross-reaction to ZIKV and was able to drive antibody-dependent enhancement (ADE) of ZIKV infection. Using a panel of human monoclonal antibodies (mAbs) to DENV, we showed that most antibodies that reacted to DENV envelope protein also reacted to ZIKV. Antibodies to linear epitopes, including the immunodominant fusion-loop epitope, were able to bind ZIKV but were unable to neutralize the virus and instead promoted ADE. Our data indicate that immunity to DENV might drive greater ZIKV replication and have clear implications for disease pathogenesis and future vaccine programs for ZIKV and DENV.

Figure 1. DENV immune plasma crossreacts with ZIKV.

(a) Binding titration curves of 6 representative DENV sera against ZIKV strains PF13 and HD78788 and DENV measured by capture ELISA (6-month convalescent plasma using the DENV serotype corresponding to their previous acute infection), control pooled non-dengue exposed plasma (PND) shows no binding (closed circles). (b) Endpoint titers of DENV plasma against ZIKV (strain PF13 and HD78788) and DENV determined by capture ELISA (n=16). Small horizontal lines indicate the median values.

Figure 2. Neutralization of ZIKV by DENV immune plasma.

(a) Neutralization of ZIKV determined on Vero cells for 6 representative DENV plasma with 2 ZIKV strains PF13 and HD78788 and DENV (6-month convalescent plasma using the DENV serotype corresponding to their recent infection). PND was used as negative control (closed circles). (b) NT50 values for DENV plasma on ZIKV and DENV infection (n=16). Small horizontal lines indicate the median values.

Figure 3. DENV plasma enhances ZIKV infection.

(a) Flow cytometric profiles of U937 cells infected with ZIKV strains PF13 and HD78788 and DENV serotype 2 in the absence or presence of 1:10,000 PCS (the dilution giving peak enhancement) demonstrating the low background infection. (b) ADE curves (fold increase in FFU) of U937 cells infected with ZIKV (strain PF13 and HD78788) and DENV serotype 2 using PCS and PND. (c) Six representative ADE curves (fold increase in FFU) of U937 cells infected with ZIKV strains PF13 and HD78788 and DENV (6-month convalescent plasma using the DENV serotype 2 in the presence of serially diluted DENV plasma). PND was used as negative control (closed circles). (d) Peak fold enhancement (fold increase in FFU) of DENV plasma on ZIKV and DENV (n=16). Small horizontal lines indicate the median values.

Figure 4. Anti- DENV human monoclonal antibodies bind to ZIKV.

(a) Binding of ZIKV strains PF13 and HD78788 and DENV serotype 1 by 33, 17, 45, 37 of anti-EDE1, EDE2, FLE and non-FLE mAbs at 10 μg/ml, also included are 12 mAbs termed IB-3, IB-4 and IB-5 which were poorly neutralizing but reacted to a conformational epitope that was lost when envelope protein was denatured by immunoblotting. These data are representative of three separate experiments. The arrows indicate mAbs used in Fig. 4b, 5, and 6. (b) Binding titration curves for 9 representative mAbs (3 each for anti-EDE1, EDE2, and FLE mAbs). The data shows mean±SEM from 3 independent experiments.

Figure 5. Anti-DENV human monoclonal antibodies enhance ZIKV infection.

Infection enhancement curves (fold increase in FFU) of 9 anti-DENV mAbs (3 each for anti-EDE1, EDE2, and FLE mAbs) on ZIKV strains PF13 and HD78788. U937 cells were used as target cells. The data are shown as mean±SEM from 3 independent experiments.

Figure 6. Anti-EDE1 human monoclonal antibodies inhibit ADE of DENV plasma.

The inhibition curves of 9 anti-DENV mAbs (3 each for anti-EDE1, EDE2, and FLE mAbs) on ZIKV strains PF13 and HD78788 (fold increase in FFU). U937 cells were infected with ZIKV in the presence of 1:10,000 PCS (the dilution giving peak enhancement) together with serially diluted anti-DENV mAbs. Anti-flu mAb, 28C, was used as a negative control. The data are shown as mean±SEM from 3 independent experiments.