Both NA and HA interact with SA, and an optimal viral infection needs a balance between NA and HA activities both at the entry phase of the virus, including entry in the respiratory tract, attachment to the cell surface, and at the stage of exit after budding of viral particles (Dou et al., 2018; McAuley et al., 2019; de Vries et al., 2020). This evidence concerns the gene XK and viral infectious disease.