Figure A3. Histograms compare 43 avian allele A viruses and 306 human viruses (panels A and C), and 52 avian allele B viruses and 306 human viruses (panels B and D), based on their NS1 and NS2 genomic segments. Vertical axis shows the count for pairs of sequences with specific percent identity (rounded to integer). Red bars represent frequencies for 'homo' pairs – sequences of the same host species (human to human, or avian to avian); blue bars represent frequencies for 'hetero' pairs – pairs that cross host species (human to avian, or avian to human). Adobe Acrobat PDF available at http://wwwnc.cdc.gov/eid/pdfs/06-0276-FA3.pdf (5 pages).