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+--- Thread: Question!!! HIV - kamlesh (/showthread.php?tid=40197)
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Question!!! HIV - kamlesh - ArchivalUser - 03-11-2005
Q: Drugs which inhibit expression of Pol gene in HIV inhibits
Ans: 1. Transcription of proviral DNA
2. Production of viral m-RNA
3. Integration of Pro-viral DNA
4. Viral maturation
5. Nucleo capsid
Please explain?
0 - ArchivalUser - 03-11-2005
Ans:?1
pol gene codes for reverse transcriptase,so transcription will be affected.
correct if i am wrong.
0 - ArchivalUser - 03-11-2005
The answer is 3, Integration of Pro-viral DNA, but don't know the reason.
0 - ArchivalUser - 03-11-2005
kamlesh,
I've just lost my entire message with the explanation to your question. By the way, where did you find it, where did you get it from ? It's a very inteligent and interesting question and I'd suggest to have a discussion about reverse transcriptase in HBV, not only HIV.
The answer is A: transcription of proviral DNA.
At a glance: pol gene=reverse transcriptase= RNA-dependent DNA-polimerase.
Reverse transcriptases in retroviruses transcribe single-stranded RNA into double-stranded DNA: this is the first step of the sequence ( transcription ).
Transcribed DNA can then be integrated into host genome by an integrase enzyme: the second step of the sequence, in fact the integration.
Reverse transcriptase inhibitors: nucleosides and non-nucleosides, non-competitively inhibit reverse transcriptase of HIV: prevent incorporation or integration of viral genome into host DNA: terminate DNA transcription by viral reverse transcriptase, preventing viral replication.This implies that the transcription is affected: reverse transcripase is not produced and thus, the integration of ds-DNA into host genome no longer takes place.
Logically, the first step which is transcription is inhibited, terminated.
That's about it.
matoka
0 - ArchivalUser - 03-11-2005
The answer is definitely 3. integration of proviral DNA
Don't forget that pol gene express three gene products:
1. Reverse transcriptase (RT):viral RNA---->dsDNA
2. protease
3, integrase:integration of viral DNA ( formed through RT )into host
So if pol gene is defected, no integrase will do the integration part.
BTW, reverse transcriptase won't be associated with transcription. Transcription is from DNA to RNA with the help of RNA polymerase. But here the case is from RNA to dsDNA. It is called reverse transcription.
0 - ArchivalUser - 03-11-2005
transcription of provial DNA is done after the integration of dsDNA into the host DNA and with the help of RNA polymerase, not reverse trancriptase for sure. Make the sequence of what happens first and what next.
So first is reverse transcription, forming the dsDNA from viral RNA----> dsDNA integrated into host DNA----> formed provirus (with dsDNA)----->transcription produces ss (+) RNAs---> translation----> assembly----->release of virus
0 - ArchivalUser - 03-11-2005
thanks everyone, u guys are studying really conceptually.
i saw this Q in kaplan notes
0 - ArchivalUser - 03-11-2005
danille,
You may be right, it seems to me that I misunderstood. Thank you for posting all the sequence of events, finally I will understand this phenomena: the viral replication.
It seems to me that you're strong in molecular biology and therefore in the viral replication. That's great !
Could you please, explain the equence of events in HVB, which also has a reverse transcriptase : RNA-dependent DNA-polimerase ? There is a question in this sense in the second form of NBME self assessment tests: I think the corect answer in that question is DNA-polymerase. Do you know what I'm talking about ? Have you taken that test ? Have you taken your step 1 exam ?
Good luck on your exams.
matoka
0 - ArchivalUser - 03-11-2005
Hi Matoka, I use Kaplan and FA only. So everything the books emphasized will be my focus. I studied HIV very well since it is emphasized in the book.
I am in the field of molecular biology so I wish that my exam will have more of those Qs.
Haven't taken NMBE yet. But I won't do it, cause I have read so many those Qs on this forum.
Haven't taken my Step 1 yet either. Will do that in the first week of April. How about you?
0 - ArchivalUser - 03-11-2005
danille,
do you have kaplan notes that accompany the live lectures / i have only kaplan homestudy and those are not considered up-to-date and they aren't.
hiv and aids ;by the way, i can't use any capital letters, my laptop has trouble again; are very important and high yield topics, believe me. i don't have enough information on them, but i'd like to know the latest news regarding hiv.
as for molecular biology, it's nice to hear that you work in such a field , probably as a researcher. i've never known and understood it properly, i wish i knew it. unfortunately, molecular biology seems to be something impossible for me, something from another planet, which is not true. i studied it from kaplan homestudy and thanks haven i did not encounter an excess of questions from it on my real exam.
i did take my exam 11 days ago, i posted my exam experience on this forum, you can read it.the last time i wrote on that message was three days ago.
i'm sure that you're well prepared and will pass your step 1 exam, no doubt. best of luck on all your exams.
matoka