Here is a review that should get you started.  In general you will need a way to measure each of the RNA segments in the virus.  Probably RT-PCR coupled to cDNA sequencing would be the way to go.

J Infect Dis. 2010 Sep 1;202 Suppl:S43-8. doi: 10.1086/653548.

Genetic and antigenic diversity of human rotaviruses: potential impact on vaccination programs.

Kirkwood CD1.

As mentioned above by James RT-PCR with sequencing techniques enables exploration of viral evolution. You can go through the paper to get some idea. Here is the link to access the paper.

http://www.sciencedirect.com/science/article/pii/S136952741500079X