Nucleotide sequence alignment of NA8F primer. A sequence logo representation of 3,337 available sequences in the NCBI database at the time the study was conducted. All 9 NA subtypes were aligned against the NA8F primer and analyzed for discrepancies at the 3'end. The big letters represent the consensus sequences for each subtype. The standard mixed base definition was applied, and for reference "I" stands for inosine. aAlignment is presented in sequence logo format [32–34].