The invention generally relates to the development of variant Zika strains, cDNA clones and mRNA transcripts that contain specific mutations in the Zika ORF, and methods for producing high yields of Zika viruses (“ZIKVs”) using these variant cDNA clones, transcripts and strains. The produced ZIKVs can be used for the manufacture of purified inactivated vaccines (PIVs), which may be useful for treating ZIKV-related diseases and for providing immunoprotection against ZIKV.