Figure 1From: Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza virusesStrategy of modifying the HA cleavage site. (A). The substitution of H7N2 (VIVA/04) HA amino acid cleavage site with alternative cleavage site sequences of H6's. (B). The substitution of H9N2 (WF10) HA amino acid cleavage site with alternative cleavage site sequences of H6's.Back to article page