Question

explain both

a)Compare and contrast Class I, II, III viral fusion proteins.

b)How do retroviruses like HIV rely on multiple proteins to achieve entry? What checkpoints are involved in the process?

Answer 1

features	class I	class II	class III
proteolytic processing requirement	yes	yes	no
orientation of protein wrt viral membrane	spikular projections (perpendicular)	parallele	NA
Location	near N terminal	internal	internal
secondary structure in native form	alpha helix	beta sheet	both
oligomeric structure in native form	trimer	dimer	NA

B. HIV uses multiple fusion protein to gain entry into its host such as gp120, CD4 etc the ligand CD4 binds with gp 120 and initiate other fusion protein to fuse with host cell membrane and starts a cascade of proteins which helps HIV to gain entry into T helper cells. HIV regulate this process via G2/M checkpoint.