There is one kind of glycoprotein that participates in the recognition and membrane fusion in most virus envelopes, such as the spike (S) protein in the SARS virus, the gp160 in HIV and HA in IVs [71, 72] . These glycoproteins can bind to one specific glycan structure which is known as the lectin or GBP. Other viral glycoproteins, such as HN in the Newcastle Disease Virus or NA in IVs, function as the exoglycosidase in the release of virus particles [73] .