Novel Avian Influenza H7N3 Strain Outbreak, British Columbia

Genome sequences of chicken (low pathogenic avian influenza LPAI and highly pathogenic avian influenza HPAI) and human isolates from a 2004 outbreak of H7N3 avian influenza in Canada showed a novel insertion in the HA0 cleavage site of the human and HPAI isolate. This insertion likely occurred by recombination between the hemagglutination and matrix genes in the LPAI virus.