You may want to check this interesting video:

http://www.jove.com/video/54767/zika-virus-infectious-cell-culture-system-vitro-prophylactic-effect

hey John,

thanks for the link. I will definitely add centrifugation in the method. But they also use 10% FBS in the medium. Is there an alternative to get rid of this FBS?

I believe that there are serum-free growth medium that are commercially available like this one:

http://www.lonza.com/products-services/bio-research/cell-culture-products/specialty-media/hek293-vero-mdck-expression-media/provero-1-serum-free-medium.aspx

You can grow virus in VP-SFM + Gln which does not contain serum.

Centrifugation over a gradient cushion works well (e.g. 25% glycerol or 30% surcrose), alternatives would be dialysis (time consuming) or transverse flow filtration (requires specialized equipment for larger batches).