Understanding Excretion and Infectivity of Zika Virus in Semen During and After Infection

Every two weeks subjects provide a semen sample which is analysed and then frozen for RT-PCR and viral load. Semen sample testing for the presence of ZIKV (Institute of Tropical Medicine, Belgium) will be performed using both a ZIKV-specific, in-house duplex real-time RT-PCR, targeting a 102bp and 121bp sequence of the NS5 gene and the RealStar® Zika Virus RT-PCR Kit (Altona). Quantitative viral load RNA measurements will be expressed utilizing threshold cycle values because a standardized viral load reference method is not available. To test for infectivity of ZIKV in semen, ZIKV isolation will be attempted in semen samples with a high viral ZIKV load (i.e. positive ZIKV PCR result and Ct-values below 30) by inoculation in Vero cells.