HIV

Question 1

What is the main structural polyprotein involved in HIV-1 assembly?

Answer 1

Gag (Pr55Gag)

Question 2

What are the domains of the Gag polyprotein?

Answer 2

MA (Matrix)

CA (Capsid)

SP1 (Spacer peptide 1)

NC (Nucleocapsid)

SP2

p6

Question 3

Where does HIV assembly occur in the host cell?

Answer 3

At the inner leaflet of the plasma membrane

Question 4

What is the function of the Matrix (MA) domain of Gag?

Answer 4

It targets Gag to the plasma membrane via myristoylation and PI(4,5)P₂ interaction

Question 5

How does the Capsid (CA) domain contribute to HIV structure?

Answer 5

It forms the conical core of the mature virion and is essential for both immature lattice formation and mature core assembly

Question 6

What role does the Nucleocapsid (NC) domain play?

Answer 6

It binds and packages the viral RNA genome, using zinc finger motifs

Question 7

What triggers the maturation of HIV particles?

Answer 7

Proteolytic cleavage of Gag by the HIV-1 protease after budding

Question 8

What structural transition occurs during HIV maturation?

Answer 8

Gag transitions from a hexameric immature lattice to a cone-shaped mature capsid

Question 9

Which region between CA and NC is essential for core stability?

Answer 9

SP1 – cleavage here is critical for the immature-to-mature transition

Question 10

What are the therapeutic implications of targeting HIV maturation?

Answer 10

Inhibitors that block Gag cleavage (e.g. maturation inhibitors like Bevirimat) prevent HIV from becoming infectious

Question 11

What technique has revealed most of the high-resolution structures of HIV capsid?

Answer 11

Cryo-electron microscopy (Cryo-EM) and X-ray crystallography

Question 12

What is the significance of the “six-helix bundle” in the immature Gag lattice?

Answer 12

It stabilizes the SP1 region and is a target for maturation inhibitors