Hi Ed and welcome to NeuroTalk. I'm sorry such a frightening event has brought you here but there are many here who can relate to your situation.
We have a large MS community and there is a thread in the MS Forum dedicated especially to Tysabri. Here it is:
http://neurotalk.psychcentral.com/thread142931.html
I'll also include the link to the MS Forum itself.
http://neurotalk.psychcentral.com/forum17.html
I hope you can find some answers to your questions. Your daughter is very fortunate to have a Dad that cares so much.