Viral particles and virion RNAs were purified according to the method of Peden and Symons (44) . Individual viral RNAs were purified from the virion RNAs first via an agarose gel and then via a polyacrylamide gel (45) . The purified, single, viral RNAs were polyadenylated with Escherichia coli poly(A) polymerase and then RT-PCR was done using an oligo dT primer as described previously (43) . The amplified products were cloned into the pBluescript SK + vector and sequenced from both orientations.