Understanding Retroviruses

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Trying to understand how a retrovirus works, would love it if someone could please let me know if I'm correct or not:
the retrovirus, which requires an envelope, contains RNA (as opposed to most other viruses containing DNA). After attaching to a host cell, the virus injects its RNA into the host cell. Then, because the RNA can readily code for proteins, it uses the cell's machinery to code reverse transcriptase (or is it already included? if so, it needs to make more right?). Then, the RNA injected by the cell is converted to DNA, which is subsequently injected into the host genome (then goes to either lytic or lysogenic cycle), and is then converted to RNA again at later points...

Essentially, I'm a bit confused about where the reverse transcriptase comes from

Thanks!

 

[Velocity]

Trying to understand how a retrovirus works, would love it if someone could please let me know if I'm correct or not:
the retrovirus, which requires an envelope, contains RNA (as opposed to most other viruses containing DNA). After attaching to a host cell, the virus injects its RNA into the host cell. Then, because the RNA can readily code for proteins, it uses the cell's machinery to code reverse transcriptase. Then, the RNA injected by the cell is converted to DNA, which is subsequently injected into the host genome (then goes to either lytic or lysogenic cycle), and is then converted to RNA again at later points...

I'm a bit confused about where the reverse transcriptase comes from, does that sound right?

Thanks!

That sounds about right. I think that in some cases the virus already contains some of the proteins needed for reverse transcription, but others (such as HIV) simply code for it. In either case, the virus provides it in some form; if you get a question that's really specific, I'd assume that they're using HIV as an example, and would indicate that the proteins are produced by the cell from the virus' RNA.

However, one note: with many of these viruses, there is no "injection of DNA" occurring (you're probably thinking of the T4 phage) - the virus binds to the cell and either fuses (viral membrane is lost, but the contents within the membrane are released into the host cell) or is absorbed (whether by pinocytosis or endocytosis, this brings the entire viral molecule into the cell). In the case of the viral particle being absorbed, the viral membrane is typically broken down within the cell, which releases the viral payload.

 

[thestrokes14]

Exactly. Injections are typically indicative of bacteriophage.

 

[whiteshadodw]

usually animal viruses just have outer membranes which makes endocytosis or pinocytosis easier. bacterial viruses have protein coats on them.