June 23, 2017
This groundbreaking study "Zika virus pathogenesis in rhesus macaques is unaffected by pre-existing immunity to dengue virus" was published in June 2017 in Nature Communications and is co-authored by Aravinda de Silva PhD, professor of microbiology and immunology at the University of North Carolina-Chapel Hill - a ZikaPLAN Partner.
Concerns about the worsening of a Zika (ZIKV) infection after prior dengue infection have frequently been raised. Indeed, cross-reactive antibodies (Abs) could potentially affect ZIKV pathogenesis. It has been shown in vitro that antibody-dependent enhancement (ADE) of ZIKV infection can occur due to pre-existing dengue (DENV) antibodies. If this were to be proved accurate, it would also negatively affect Zika vaccine development as concurrently live dengue vaccines are being rolled out in several countries where Zika is circulating.
In the study, the effects of pre-existing DENV immunity on ZIKV infection in vivo are examined. Two cohorts of rhesus macaques are infected with ZIKV; one cohort having been exposed to DENV 2.8 years earlier and the second control cohort being naïve to flaviviral infection.
The results, while confirming ADE in vitro, suggest that pre-existing DENV immunity does not result in more severe ZIKV disease. Rather, the results show a reduction in the number of days of ZIKV viremia compared to naïve macaques and that the previous exposure to DENV may result in modulation of the immune response without resulting in enhancement of ZIKV pathogenesis.
These results are, therefore, good news for the Zika and dengue vaccine community.