lication ▁cycle . ▁They ▁found ▁out ▁that ▁by ▁dis abling ▁hem ag gl ut in in ▁and ▁neur amin id ase , ▁the ▁number ▁of ▁vir uses ▁exit ing ▁from ▁the ▁host ▁cells ▁decre ased ▁by ▁ 9 0 %. ▁Hence , ▁they ▁proved ▁that ▁hem ag gl ut in in ▁and ▁neur amin id ase ▁are ▁necessary ▁for ▁a ▁complete ▁vir al ▁rep lication ▁cycle . ▁In ▁further ▁research , ▁Lamb ▁concluded ▁that ▁hem ag gl ut in in ▁g athers ▁at ▁li pid ▁ra ft s ▁for ▁an ▁ade qu ate ▁concentration ▁in ▁the ▁bud ding ▁vir uses , ▁which ▁results ▁in ▁easy ▁entry ▁into ▁the ▁next ▁cell . ▁ ▁In ▁collaboration ▁with ▁Ted ▁J ard etz ky , ▁Lamb ▁determined ▁the ▁mole cular ▁structure ▁of ▁one ▁of ▁the ▁pre - ▁and ▁post - f usion ▁forms ▁of ▁the ▁param y x ov irus ▁fusion ▁protein , ▁which ▁causes ▁the ▁virus ▁memb rane ▁to ▁f use ▁with ▁the ▁cell ▁surface ▁memb rane . ▁Studies ▁on ▁the ▁fusion ▁protein ▁were ▁applicable ▁to ▁the ▁en velope ▁prote ins ▁of ▁S AR S ▁coron av irus , ▁H IV ▁and ▁E bol a ▁virus . ▁All ▁of ▁the ▁vir al ▁fusion ▁prote ins ▁under go ▁a ▁remarkable ▁protein ▁ref old ing ▁event ▁and ▁this ▁process ▁brings ▁about ▁fusion ▁of ▁the ▁vir al ▁and ▁cell ular ▁memb ran es . ▁ ▁In ▁ 1 9 9 2 ▁( for ▁influen za ▁A ▁virus ) ▁and ▁ 2 0 0 3 ▁( for ▁influen za ▁B