Changes in viral envelope structure preceding infection.
D002213:Capsid / Q000502:physiology*; D002459:Cell Fusion; D004910:Erythrocyte Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing; D008566:Membranes / Q000648:ultrastructure; D010222:Parainfluenza Virus 1, Human / Q000502:physiology* / Q000648:ultrastructure; D014764:Viral Proteins / Q000502:physiology*
D014764:Viral Proteins