Impact of prior flavivirus immunity on Zika virus infection in rhesus macaques

Abstract

Studies have demonstrated cross-reactivity of anti-dengue virus (DENV) antibodies in human sera against Zika virus (ZIKV), promoting increased ZIKV infection in vitro. However, the correlation between in vitro and in vivo findings is not well characterized. Thus, we evaluated the impact of heterotypic flavivirus immunity on ZIKV titers in biofluids of rhesus macaques. Animals previously infected (≥420 days) with DENV2, DENV4, or yellow fever virus were compared to flavivirus-naïve animals following infection with a Brazilian ZIKV strain. Sera from DENV-immune macaques demonstrated cross-reactivity with ZIKV by antibody-binding and neutralization assays prior to ZIKV infection, and promoted increased ZIKV infection in cell culture assays. Despite these findings, no significant differences between flavivirus-naïve and immune animals were observed in viral titers, neutralizing antibody levels, or immune cell kinetics following ZIKV infection. These results indicate that prior infection with heterologous flaviviruses neither conferred protection nor increased observed ZIKV titers in this non-human primate ZIKV infection model.

Durability and correlates of vaccine protection against Zika virus in rhesus monkeys

“…Previous studies have suggested that DENV-specific antibodies can increase ZIKV replication in vitro and in mice (28–30), but studies in primates have to date not replicated these findings (31, 32). Dedicated studies of ZIKV vaccines in DENV-exposed animals and humans are therefore warranted.…”

Route of inoculation and mosquito vector exposure modulate dengue virus replication kinetics and immune responses in rhesus macaques

“…Neutralizing antibody titers in heat-inactivated sera between the primary infection and secondary infection phases of the experiment were determined using a 96-well, high-throughput, flow cytometry-based neutralization assay as previously described. [79] Serial dilutions of sera were mixed with an equal volume of virus, diluted to achieve 10-15% infection of cells/well, and incubated for 1h at 37˚C. After 1h of incubation, an equal volume of medium (RPMI-1640 supplemented with 10% FBS, 1% penicillin/streptomycin, 1% L-glutamine (200mM), and 1% nonessential amino acids (10mM)) containing 5x10 4 U937-DC-SIGN cells were added to each serum-virus mixture and incubated 18-20 h overnight in a 37˚C, 5% CO2, humidified incubator.…”

“…In vitro antibody-dependent enhancement of DENV infection was quantified as previously described. [79] Beginning at 1:40, two-fold serial dilutions of heat-inactivated day 0 sera were incubated with virus (in sufficient amount to infect 10-15% of U937-DC-SIGN cells) at 1:1 for 1h at 37˚C. This mixture was then added to a 96-well plate containing 5x10 4 cells (K562) per well in duplicate.…”

Zika virus infection of first-trimester human placentas: utility of an explant model of replication to evaluate correlates of immune protection ex vivo

“…Notably, depletion of CD4 + and CD8 + T lymphocytes from mice immunized with a DNA vaccine prior to challenge did not abrogate the protective effect of the vaccine [80], and passive transfer of immune serum from immunized animals showed similar protective effects, suggesting protection can be conferred by antibodies alone. Interestingly, no significant differences in ZIKV titers, neutralizing antibody levels, or immune cell kinetics were found following ZIKV infection of flavivirus-naïve and dengue-immune animals [84]. …”