11.1 Rotavirus

Question 1

Describe the structure of Rotaviruses

Answer 1

• Viral capsid is triple layered
• the inner layer contains the virus genome
• genome is comprised of 11 segments of dsRNA
• each dsRNA encodes for products that are either structural or non structural viral proteins

Question 2

What are the functions of VP4 and VP7?

Answer 2

VP4 is on the surface of the vision that protrudes as a spike. It binds to receptors and drives the entry of the virus into the cell.

VP7 is a glycoprotein that forms the outer surface of the virion. Apart from its structural functions, it determines the G-type of the train and, along with VP4, is involved in immunity to infection

Question 3

What is a viroplasm

Answer 3

The site of RNA replication (minus the strand synthesis) and core + DLP assembly

Question 4

Which virus protein acts as an enterotoxin?

Answer 4

NSP4

Question 5

Describe the production of the rotashield vaccine

Answer 5

Contained reassortments each with different human serotype of VP4 or VP7 which is safe and immunogenicity.

In 1999 it was pulled from the market because of an association between the vaccine and an increased risk of intussusception in infants aged one year or younger

Question 6

What is intussusception and what is its association with the rotavirus vaccine?

Answer 6

Intussusception occurs when one portion of the bowel slides into the next, much like the pieces of a telescope. When this occurs it creates an obstruction in the bowel.

It increased as a risk with the rotavirus vaccine

Question 7

What other vaccines have become available and describe them

Answer 7

Rotateq - was licenced for use in the United States and is a live pentavalent human bovine reassortment vaccine

Rotarix - was licensed for use in the UK and is a monovalent vaccine derived from the most common human rotavirus strain G1P

Question 8

What are the main problems with rotavirus vaccines?

Answer 8

Does not cover all serotypes

Question 9

List the basic steps of rotavirus replication

Answer 9

The rotavirus triple layered particles first attach to sialo-glycans on the host cell surface, followed by interactions with other cellular receptors, including integrals and Hsc70. Virus is then internalised by receptor-mediated endocytosis.

Question 10

Describe the dual classification system for rotaviruses

Answer 10

Because of the two structural viral proteins found on the surface of the capsid.

1. VP7 is a glycoprotein and also known as the Gprotein which determines the G serotype of which there are 10 in humans.
2. VP4 is the protease sensitive protein or Pprotein and there are eight P serotypes to have been characterised in humans.