Baltimore Classification

Question 1

What is the Baltimore classification?

Answer 1

A classification that categorises viruses based on their type of genome and method of mRNA synthesis

Question 2

What are all the groups in the Baltimore classification in order?

Answer 2

Group I - dsDNA viruses
Group II - ssDNA viruses
Group II - dsRNA viruses
Group IV - positive sense ssRNA viruses
Group V - negative sense ssRNA viruses
Group VI - (+) ssRNA viruses with DNA intermediate
Group VII - dsDNA viruses with RNA intermediate

Question 3

dsDNA viruses - How do they produce mRNA, and what is an example of one

Answer 3

mRNA transcribed directly from DNA template using host RNA polymerase.

Example = Herpesviruses

Question 4

ssDNA viruses - How do they produce mRNA, and what is an example of one?

Answer 4

ssDNA is converted to dsDNA by host DNA polymerase, then transcribed to mRNA

Example = Parvoviruses

Question 5

dsRNA viruses - How do they produce mRNA, and what is an example of one

Answer 5

dsRNA genome is transcribed to mRNA by viral RdRP

Example is Rotaviruses

Question 6

Positive sense ssRNA - How do they produce mRNA, and what is an example of one?

Answer 6

+ssRNA genome serves itself as mRNA

Example is Polioviruses

Question 7

Negative sense ssRNA - How do they produce mRNA, and what is an example of one?

Answer 7

-ssRNA genome is transcribed to mRNA by RdRP

Example is Influenza viruses

Question 8

ssRNA viruses with DNA intermediate - How do they produce mRNA, and what is an example of one?

Answer 8

ssRNA is reverse transcribed into dsDNA (by reverse transcriptase), then transcribed to mRNA by host RNA polymerase

Example is retroviruses (like HIV)

Question 9

dsDNA viruses with an RNA intermediate

Answer 9

dsDNA is transcribed to RNA, which is then reverse transcribed back to DNA.
The RNA intermediate is used to produce mRNA

Example is Hepatitis B virus