This study examined the current status of Zika and effects of pre-existing dengue immunity to Zika virus (ZIKV) infection in Southern Taiwan.
Phylogenetic tree was used to analyze the phylogeny of detected ZIKVs. Paired sera from dengue patients were collected for the determination of dengue and Zika infection. Plaque reduction neutralization test (PRNT) and qRT-PCR were used to determine the titers of neutralizing antibodies and viruses, respectively. Antibody-dependent enhancement(ADE) assay was used to evaluate the effect of anti-dengue antibodies on ZIKV infection.
Epidemiological data indicate that continuous importation of ZIKV infection from neighboring Zika epidemic countries was detected in Taiwan. Further, a total of 78 dengue patients were enrolled and 21 paired sera samples were obtained. PRNT results indicated that a total of 8 and 13 sera were identified as primary and secondary dengue infection, respectively and 2 samples were positive for ZIKV(MR766). Results from ADE assay indicate that convalescent sera from primary and secondary dengue infection displayed significant ADE of the ZIKV infection compared to the healthy control (p < 0.05).
This study suggests that pre-existing dengue immunity facilitates ZIKV infection and continuous importation of ZIKV infection may pose a threat to the indigenous Zika emergence in Southern Taiwan.

Copyright © 2020. Published by Elsevier Ltd.