The variation of highly pathogenic avian influenza H5N1 virus results in gradually increased virulence in poultry. and human cases continue to accumulate. The neuraminidase (NA) stalk region of influenza virus varies considerably and may associate with its virulence. The NA stalk region of all N1 subtype influenza A viruses can be divided into six different stalk-motifs. https://mainlandskateandsurfes.shop/product-category/boys-youth-tees/