Introduction 2

Question 1

What is the genome of HepC?

Answer 1

Single stranded, positive sense, RNA

Question 2

How does HepC enter a cell?

Answer 2

Must contact at least 3/4 receptors before invagination into an endosome. Acidification causes the HCV glcyoprotein to fuse with the membrane, then coating and genome release.

Question 3

Describe the cell exit of HepC.

Answer 3

HepC replicates within a membranous web of the ER, in close association with lipid droplets and ApoB precursor lipoprotein. Infectious viral particles are trafficking through the Golgi and released at the plasma membrane.

Question 4

How are progeny positive RNA strands synthesised?

Answer 4

RNA acts as a template to make negative RNA, which together go on to make dsDNA. This then synthesises progeny positive RNA.

Question 5

Describe the virion assembly of a small RNA virus.

Answer 5

Non-cleaved proteins undergo autocatalytic-cleavage to make VP1,3,0. These form 12 pentamers which form 73S empty capsids with capsid holes for viral RNA entry. Low pH causes VP0 cleavage in VP2,4 which causes closure of the capsid holes.

Question 6

In serological testing, what are you looking for in the paired sera?

Answer 6

Antibody increase in the convalescent sample compared to the acute sample, for the suspected virus.

Question 7

Why is indirect immunofluorescent testing better than direct?

Answer 7

Time consuming to label all of the possible antisera for the viral antigens.

Question 8

What is the difference between direct penetration and endocytosis in viral entry?

Answer 8

Direct entry: conformational changes in viral proteins to expose fusion domains, enabling fusion with cell membrane.
Endocytosis: virus protein and cell receptor binding trigger a signalling cascade which initiates uptake into an endosome.