Question 1

The subgenomic mRNA from togaviruses is synthesized from a subgenomic negative-strand RNA.

Accepted Answer

The answer of The subgenomic mRNA from togaviruses is synthesized...

Question 2

Alphaviruses, which are members of the togavirus family, have been developed as useful vectors for the expression of proteins in various human and insect cells.Describe two situations where alphaviruses could be used as vectors in biology or medicine.

Accepted Answer

The answer of Alphaviruses, which are members of the togavirus...

Question 3

One of the advantages of the alphavirus vector that uses a double subgenomic RNA for expressing foreign proteins is that it does NOT need a helper virus to produce virions.

Accepted Answer

This statement is correct. The double subgenomic RNA in the alphavirus vector allows for efficient expression of foreign proteins without the need for a helper virus to produce virions. This is one of the advantages of this vector system.

Question 4

The production of the subgenomic mRNA allows togaviruses to synthesize 10 times more structural proteins than non-structural proteins.

Accepted Answer

Togaviruses use a mechanism called subgenomic mRNA synthesis to produce more structural proteins than non-structural proteins. This allows for a more efficient viral replication cycle.

Question 5

The P123 version of the polymerase protein from togaviruses can autocatalytically cleave itself into the individual nonstructural proteins.

Accepted Answer

The P123 (or its equivalent) polyprotein in togaviruses does not autocatalytically cleave itself; instead, proteolytic cleavage to produce individual nonstructural proteins is typically mediated by a viral protease encoded within the polyprotein itself or by host cell proteases.

Question 6

The togaviruses have their non-structural protein coding sequences at the 5' end of the viral genome while the picornaviruses and the flaviviruses have the non-structural protein coding sequences at the 5' end.Explain how this difference is important in the replication cycle of the togaviruses.

Accepted Answer

The answer of The togaviruses have their non-structural protein coding...

Question 7

There are two proposed mechanisms for how togaviruses assemble their virions.Describe the two mechanisms and any available evidence that supports them.

Accepted Answer

The answer of There are two proposed mechanisms for how...

Quiz 13: Togaviruses