Reverse transcription polymerase chain reaction

RT-PCR assays in Balb/c mice were used to monitor VL as previously described (6). RNA was extracted from plasma with QIAcube HT (Qiagen, Germany). The wild-type ZIKV BeH815744 Cap gene was used as a standard. RNA was purified (Zymo Research), and RNA quality and concentration were assessed by the BIDMC Molecular Core Facility. Log dilutions of the RNA standard were reverse transcribed and included with each RT-PCR assay. VL were calculated as virus particles per milliliter. RT-PCR assessment of VL in sera of IFNAR^−/− mice was performed on day 2 (peak of viremia) using ZIKV M primers [as previously described (9)] with normalization to RPL13A.