Yes exactly,
All what you said makes sense and is correct
All what you said makes sense and is correct
DNA-dependent DNA polymerase
What exactly does these sentence from First Aid mean?
(Under HBV)
"Cellular RNA polyerase transcribes RNA from DNA template. Reverse transcriptase transcribes DNA genome from RNA intermediate. However, the virion enzyme is a DNA-dependent DNA polymerase."
Okay, the first sentence (correct me if I am wrong) means that our cell's RNA polymerase makes RNA from HBV's DNA. The 2nd sentence means that HBV has reverse transcriptase that makes back its DNA from the RNA that our RNA polymerase has just made?
What would the 3rd sentence mean? Has it got any relation with the fact that HBV can incorprate its DNA into our cells?
(Under HBV)
"Cellular RNA polyerase transcribes RNA from DNA template. Reverse transcriptase transcribes DNA genome from RNA intermediate. However, the virion enzyme is a DNA-dependent DNA polymerase."
Okay, the first sentence (correct me if I am wrong) means that our cell's RNA polymerase makes RNA from HBV's DNA. The 2nd sentence means that HBV has reverse transcriptase that makes back its DNA from the RNA that our RNA polymerase has just made?
What would the 3rd sentence mean? Has it got any relation with the fact that HBV can incorprate its DNA into our cells?
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That statement is referring to how HBV makes it's DNA copies inside the host cell.
Since HBV is a DNA virus, it uses DNA-Dep-DNA polymerase. All this means is this:
1. HBV starts with a parental Genome that is dsDNA
2. It then forms an intermediate that is ssRNA
3. Lastly it ends up with a dsDNA progeny
So all that sentence is saying is that although there is a RNA intermediate, overall the HBV polyermase enzyme is DNA dep.
Hope that helped.
Since HBV is a DNA virus, it uses DNA-Dep-DNA polymerase. All this means is this:
1. HBV starts with a parental Genome that is dsDNA
2. It then forms an intermediate that is ssRNA
3. Lastly it ends up with a dsDNA progeny
So all that sentence is saying is that although there is a RNA intermediate, overall the HBV polyermase enzyme is DNA dep.
Hope that helped
.
the statement "DNA dependent DNA polymerase" is wrong. There's no such thing in HBV. The only virion associated enzyme is reverse transcriptase which makes DNA from the RNA intermediate. However, it's called reverse transcriptase in retroviruses while in HBV they call it DNA polymerase.
So as housewannabe told you and you have figured out;
First you have double stranded DNA viral genome this will enter the nucleus after uncoating and then after repair it transforms into closed circular dsDNA and then the host's RNA polymerase II makes mRNA from it. This mRNA is transcribed in the nucleus making viral capsid proteins (which go out to the cytoplasm) then the mRNA itself goes out to the cytoplasm where "the virion associated DNA polymerase" will make from it the progeny viral DNA.
HBV does not integrate it's genome into the host DNA, it stays episomal.
I include the Wikipedia image here for clarification
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So as housewannabe told you and you have figured out;
First you have double stranded DNA viral genome this will enter the nucleus after uncoating and then after repair it transforms into closed circular dsDNA and then the host's RNA polymerase II makes mRNA from it. This mRNA is transcribed in the nucleus making viral capsid proteins (which go out to the cytoplasm) then the mRNA itself goes out to the cytoplasm where "the virion associated DNA polymerase" will make from it the progeny viral DNA.
HBV does not integrate it's genome into the host DNA, it stays episomal.
I include the Wikipedia image here for clarification
Ahh, I see! Thanks Sabio for the explanation
But one question though,
But one question though,
I always thought the mechanism by which HBV can cause Hepatocellular carcinoma is by integrating its DNA into hepatocyte's DNA. Am I wrong or have I misunderstood you sentence?
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