There is Qiagen RNeasy kit that you can use for the extraction of viral RNA from cell culture. It all depends on the scale of your experiment: if you have lots of samples, I'd go with a kit that allows you to extract RNA in a 96-well format. If you only have a couple of samples, why don't you use a regular tissue RNA extraction kit or trizol?
Re. blood versus tissue: again it depends what the kit is intended to do-isolate virus from serum or whole blood. Two different things. I'd go with the tissue kit.