Ch. 13 Assembly, exit, and maturation

Question 1

virus particles are very diverse in ____. They vary from a single ____ ____ to complex structures built from many _____

Answer 1

size; nucleic acid; proteins

Question 2

Successful replication of viruses depends on execution of a required set of ____ ___ ___ ____

Answer 2

de novo assembly reactions

Question 3

There is a paradox: viral assembly requires production of a _____ ____, however they must also be able to _______ efficiently.

Answer 3

stable interaction; disassemble

Question 4

The first step in virus _____ is formation of the virion components

Answer 4

assembly

Question 5

Virion components must associate in an ____ ____; sometimes after transport to the appropriate ____ ___

Answer 5

orderly fashion; intracellular site

Question 6

For some virus, such as (-) strand RNA virus, protein shell formation requires binding of structural proteins to ___ ____. Other ties the first assembly rxn is formation of ___ ___ from which the shell is constructed

Answer 6

the genome; structural units

Question 7

What is the purpose of intracellular localization?

Answer 7

high conc. of viral components increases rxn rates

Question 8

What does S stand for?

Answer 8

Sedimentation rate.. which depends on mass, shape, specific volume. It is calculated as the rate at which the protein falls through a medium

Question 9

HIV1 particles assemble Gag protein in what organization? An inner coat of __ protein, which packages dimeric RNA genome is first, followed by a ___ protein and a ____protein.

Answer 9

Radial; NC; CA; MA; The MA protein lies beneath the surface of the viral envelope.

Question 10

Chaperones assist in ____ _____ _____

Answer 10

noncovalent folding. Chaperones in ER lumen also assist in glycoprotein foldingand assembly

Question 11

Poliovirus (+) sense RNA virus: Assembly of poliovirus in ____ of infected cell. Most reactions are irreversible because of _____ ____. Sometimes stable and empty capsids are assembled, which are ___ ___ _____. Formation of the 14S pentamers is coordinated with ______ ______, which requires replication of genomic RNA

Answer 11

cytoplasm; proteolytic cleavage; dead-end products

Question 12

How does HSV-1- ds RNA virus assemble?

Answer 12

Vp5 accumulates, scaffolding protein Pre-VP22a as well. Structure is formed around scaffolding and then scaffold is cleaved by viral protease

Question 13

Herpes simplex type 1 packaging
Pac1 and Pac2 with “a” terminal repeats, are packaging signals for HSV1 which interact with nucleocapsid portal. What complex assembles, allowing DNA concatemer to be reeled in? What causes cleavage of concatemer at DR1 site?

Answer 13

Terminase-complex; another poly”a” sequence

Question 14

Influenza A virus (-) sense RNA virus process of assembly:

Answer 14

Genome syn. in nucleus more mRNA, genome replication, binds M1; Allows binding of viral NEP. M1 then binds plasma membrane and HA and NA

Question 15

What is the order of HIV proteins from outer to inner? What is the process of seperating from the membrane called? What occurs after separation?

Answer 15

MA, CA, NC; N to T Terminus. budding; maturation

Question 16

What complex is formed due to complementary sequences of retrovirus genome? What is present on 5’ end of HIV1 genome? tRNA PBS and packaging signal

Answer 16

kissing loop

Question 17

There are 4 budding strategies. What viral components are necessary?

Answer 17

nucleocapsid Sindbis virus; matrix HIV Gag; envelope proteins SARS; matrix proteins + other proteins Rhabdovirus and orthomyxovirus

Question 18

How was it found that Gag P6 matrix protein was essential for budding? What part is hypothesized to be involved?

Answer 18

Mutation prevented viral release; late assembly domains which recruit cellular proteins involved in trafficking

Question 19

Look at slide 17, 18, 19

Answer 19

…

Question 20

Actin Tails can ____ the virus out of the membrane

Answer 20

push