ERVW-1 and Zika virus infectious disease: To determine how levels of CD24 expression affected ZIKV infection, CD24-low and -high cells were infected at a multiplicity of infection (MOI) of 0.5, and the percentage of cells expressing ZIKV envelope protein (Env+ cells) was quantified by flow cytometry on 1, 2, and 3 days post-infection (dpi).