SYBR green real-time PCR primers for the identification and quantification of the NA and NS genes containing or not containing amino-acid deletions in the viral cDNAs.

NA-Fa, the primer was targeted to the nucleotide sequence of the 20-amino-acid insertion in the NA stalk.

NS-Fb, the primer was targeted to the nucleotide sequence of the five-amino-acid insertion in the NS1 protein.