Viral Hepatitis

[MudPhud20XX]

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Here is one of Kaplan micro questions:

Which of the following viruses possess reverse transcriptase activity?
A. Adenoviruses and hepadnaviruses
B. Calciviruses and adenoviruses
C. Hepadnaviruses
D. Hepadnaviruses and retroviruses
E. Retroviruses

I chose E, but the answer is D.

As far as I know, reverse transcriptase is needed for RNA viruse to make DNA form RNA for replication.
Last time I checked Hepadnaviruses are ds DNA virus, so what is going on? Why does a DNA virus need reverse transcriptase?

Many thanks in advance.

 

[J ROD]

Here is one of Kaplan micro questions:

Which of the following viruses possess reverse transcriptase activity?
A. Adenoviruses and hepadnaviruses
B. Calciviruses and adenoviruses
C. Hepadnaviruses
D. Hepadnaviruses and retroviruses
E. Retroviruses

I chose E, but the answer is D.

As far as I know, reverse transcriptase is needed for RNA viruse to make DNA form RNA for replication.
Last time I checked Hepadnaviruses are ds DNA virus, so what is going on? Why does a DNA virus need reverse transcriptase?

Many thanks in advance.

Hepadna are weird. They mentioned this in DIT. I just happened to remember they use a RNA intermediate for some reason.

"Hepadnaviruses replicate through an RNA intermediate (which they transcribe back into cDNA using reverse transcriptase). The reverse transcriptase becomes covalently linked to a short 3- or 4-nucleotide primer.[1] Most hepadnaviruses will only replicate in specific hosts, and this makes experiments using in vitro methods very difficult."

 

[MudPhud20XX]

Thanks! Good to hear that DIT mentioned this, I'll keep that in my mind.

 

[J ROD]

If I remember correctly, she said they were "weird, little viruses" lol

 

[Psai]

Hepadnavirus is hep b
All the other hepatitis viruses are rna but this one is a partial dsdna. You can think of it as a hepatitis virus that made a mistake way back in the day and now has to use reverse transcriptase to get back to its roots so it can replicate