Genomic and Phylogenetic Analysis of Zika Virus Isolates from Asymptomatic Blood Donors in the United States and Puerto Rico, 2016.

Zika virus (ZIKV) caused a public health threat in the United States in 2016, leading to rapid development and implementation of blood screening assays for ZIKV RNA. Several ZIKV sequences from clinical cases have been reported, but none from asymptomatic/pre-symptomatic infections. We isolated and sequenced ZIKV from asymptomatic/pre-symptomatic blood donor (ABD-ZIKV) samples and compared with reported clinical sequences. Twelve ABD-ZIKV isolates were produced from 67 cultivated samples, and isolates were genetically similar among themselves. Most isolates shared mutations with the clinical isolate PRVABC59 2015, whereas two ABD-ZIKV isolates shared specific mutations with U.S. clinical isolates from 2016. The ABD-ZIKV strains clustered into two distinct subclades: one comprised mostly ABD-ZIKV from Puerto Rico, and another one comprised ABD-ZIKV from Florida and QTX-02 isolate (Puerto Rico). In this study, we showed the circulation of two slightly distinct virus strains among Puerto Rico blood donors, one of which was also reported in Florida.